ATI · E-5 BIB · Entry 1 of 13 · Publication

AVIATION MAINTENANCE RATINGS (AMR)

NAVEDTRA 14022A · CHAPTER 1, 4

CHAPTER 1

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equipment (SE) to the squadrons. Squadron maintenance personnel are usually assigned to the squadron maintenance department. However, some personnel may be assigned temporarily to the station’s or ship’s AIMD. Maintenance Types The term aircraft maintenance has a very general meaning. It could mean the maintenance performed in minutes at the squadron level to months of overhaul in an industrial-type facility. More than the words maintenance or aircraft maintenance are needed to indicate a specific meaning. There are two major types of maintenance-rework and upkeep. Categories within the major types of maintenance are standard rework and upkeep and special rework and upkeep. The following paragraphs discuss these types and categories of maintenance. REWORK MAINTENANCE.—Rework main- tenance is the restorative or additive work performed on aircraft, aircraft equipment, and aircraft SE. Naval aviation depots, contractor plants, and other industrial establishments do this type of maintenance. Standard rework and special rework come under the general heading of rework maintenance. Standard Rework. —Standard rework is a com- prehensive depot-level inspection of selected aircraft structures and materials, correction of critical defects, incorporation of certain technical directives, and limited removal and rework of scheduled removal components (SRCs). It also includes equipment history record (EHR), assembly service record (ASR), and module service record (MSR) items. Standard rework is commonly known as standard depot-level maintenance (SDLM). Special Rework. —Special rework is work done to aircraft, aircraft equipment, and aircraft SE to improve or change their capability to perform specific functions. This is done by replacing or repairing parts or equipment of the aircraft. Normally, special rework is depot-level work. UPKEEP MAINTENANCE. —Upkeep main- tenance is the preventive, restorative, or additive work performed on aircraft, equipment, and SE by operating units and aircraft SE activities. It includes servicing, periodic inspection, functional and bench tests, replacement, preservation, modification, and repair. Upkeep is divided into two categories, standard and special. Military and contractor personnel perform upkeep. The aircraft controlling custodians (ACCs) manage the process. Standard Upkeep .—Standard upkeep main- tenance is the periodic or scheduled work performed on aircraft, equipment, and SE after (and as a result of) completion of a prescribed number of flying hours or calendar days. Such work is performed in compliance with prescribed inspection or replacement requirements, and is also known as scheduled maintenance. Special Upkeep .—Special upkeep is the work done to aircraft, equipment, and SE to improve, change, or restore their capability to perform specific mission functions. Special upkeep maintenance includes replacement, removal, addition, alteration, or repair of parts, equipment, or aircraft without regard to flying hours or operating times, and is also known as unscheduled maintenance. Q3. What are the major types of aircraft maintenance? Q4. The restorative or additive work performed on aircraft, equipment, or support equipment is what type of maintenance? Q5. Standard rework is also known as what type of maintenance? Q6. What is special rework? Q7. Upkeep maintenance is performed by what activities? Q8. Standard upkeep is also known as what type of maintenance? Q9. Maintenance performed on aircraft without regard to operating hours or calendar is known as what type of maintenance? Maintenance Levels All aircraft maintenance functions are divided into three distinct levels-organizational, intermediate, and depot. To determine the extent to which a repair task can be undertaken, the maintenance activity refers to the maintenance instruction manuals (MIMs), the operating and service instruction manuals, or the technical directives (TDs) that pertain to each weapon system or component. The levels of maintenance are discussed in the following paragraphs. Organizational-level maintenance is work performed by an operating unit on a day-to-day basis in support of its own operations. Maintenance 1-2

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performed at this level includes line operations, such as servicing, preflight inspections, and minor adjustments in preparation for flight; periodic inspections of aircraft and equipment and the associated tests, repairs, and adjustments that do not require shop facilities; and component removal and installation. This work is done in facilities assigned to the operating units. These facilities may be used exclusively by a single large squadron or they may be shared by one or more smaller units. In an operating activity, permanently assigned personnel perform O-level maintenance. O-level maintenance at a naval air station (on aircraft assigned to the station) is a function of the operations maintenance division (OMD). When directed by higher authority, the OMD also provides O-level maintenance and other assistance to transient aircraft. Intermediate-level maintenance is work performed in centrally located facilities for the support of operating activities within a designated geographical area. I-level maintenance work is performed at a particular base or station, or aboard aircraft carriers (CVs/CVNs), and amphibious assault ships (LHDs/LHAs/LPDs). This level of maintenance consists of calibration, off-equipment repair, or replacement of damaged or unserviceable components or assemblies. It also consists of the manufacture of nonavailable parts, periodic inspections, and technical assistance on aircraft components and equipment from supported units. NOTE: The aircraft I-level maintenance department is commonly referred to as the SUPPORTING activity, and the O-level maintenance activity (squadron) is referred to as the SUPPORTED activity. I-level maintenance activities are manned by a small number of permanently assigned personnel and sea operational detachment (SEAOPDET) personnel, a sea duty component assigned to the shore AIMD, used to augment the aircraft carrier AIMD in support of carrier air wing embarkations. Personnel assigned TAD to intermediate maintenance activities (IMAs) from non-CV deploying squadrons or shore IMA SEAOPDETs should be assigned for the complete deployment cycle. Shore-based Navy squadrons who have I-level billets authorized should assign personnel to the supporting IMA for a minimum of 12 months. Depot maintenance is work that must be done in industrial-type facilities. Navy depot maintenance activities are manned primarily by civilians, and are known as naval aviation depots (NAVAVNDEPOTs or NADEPs). The Commander, Naval Air Systems Command (COMNAVAIRSYSCOM or NAVAIR) manages NADEPs. This level of maintenance (standard depot-level maintenance or SDLM) includes overhaul and major repair or modification of aircraft, components, and equipment. It also includes the manufacture of specified aeronautical parts to be stocked as spares, the manufacture of kits for authorized aircraft and the modification of equipment. Installation of these spare parts and incorporation of modification kits may be done at this level or at a lower level of maintenance. Depot-maintenance activities also perform special rework. Some military personnel are usually assigned to the NADEPs for training or to help in performing the I- and O-level maintenance connected to the depot facility. You can see by the above descriptions that the three levels of aircraft maintenance provide an orderly separation of the various maintenance tasks. These three separate levels of maintenance are needed because of task and equipment complexity, space requirements, the skill level of the assigned personnel, and the scope of support responsibility. Q10. Q11. Q12. Q13. Q14. Aircraft maintenance functions are divided into how many distinct levels? What are the distinct levels of aircraft maintenance? Describe organizational-level maintenance. What level of maintenance includes the manufacture of non-available parts? Depot-level maintenance is performed in what type of facility? Responsibilities The Chief of Naval Operations (CNO) sponsors and directs the NAMP. Program administration is through the operational chain of command. The Naval Supply Systems Command (NAVSUP) provides material in support of the operation and maintenance of aeronautical equipment. NAVAIR is responsible for research, design, development, testing, acquisition, and logistic support of all naval aviation procurement relating to aircraft missile targets and associated material and equipment. Some activities may be assigned the intermediate maintenance responsibility for an entire logistic area if requested by the cognizant controlling custodian. Specific activities designated to perform intermediate maintenance are authorized to 1-3

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perform higher levels of maintenance on systems and equipment unique to the assigned mission. Certain organizational maintenance activities are authorized to perform selective functions in partial intermediate support of their own operations. Navy shore activities that are assigned I-level maintenance responsibilities have an AIMD to perform assigned maintenance. Those shore activities with assigned aircraft have an OMD within the operations department. This division performs O-level maintenance on assigned aircraft and provides flight line services for transient aircraft. Naval Air Reserve Units (NARUs) perform both I-level and O-level maintenance on their assigned aircraft; however. the supporting activities provide logistic support. Naval air reserve squadrons perform O-level maintenance on their assigned aircraft while on active duty or assigned to fleet units. During regular scheduled drill periods, they perform maintenance according to the training requirements. Afloat and shore-based AIMDs are manned in a similar manner. They have a small number of permanently assigned personnel and temporarily assigned maintenance personnel from the embarked squadrons and SEAOPDETS. These temporarily assigned personnel accompany their squadron upon disembarkation. SEAOPDET personnel return to the shore-based AIMD upon completion of the ships deployment. The CV(N)/CV/LPH/LHA type of ships perform O-level and I-level maintenance on assigned aircraft. They also provide organizational and intermediate material, facilities, and SE needed by the embarked air wing, squadron, and unit. Squadrons and units perform O-level maintenance on assigned aircraft. While shore based, designated squadron maintenance personnel are temporarily assigned to the AIMD of the supporting station for training and augmentation of the support effort. When afloat, designated squadron maintenance personnel are assigned, as required, to the AIMD of the supporting ship. Specific squadrons and units, regardless of location, may be required to perform I-level maintenance functions on systems and equipments unique to their assigned aeronautical equipment and activity mission. Supporting ships or stations provide material, facilities. and SE. They also provide selected quantities of readily transportable material and SE as organizational property to the squadron or unit. Q15. The Chief of Naval Operations (CNO) has what responsibilities to the Naval Aviation Maintenance Program? Q16. Who is responsible for providing material in support of the operation and maintenance of aeronautical equipment? AIRCRAFT MAINTENANCE DEPARTMENT FUNCTIONS LEARNING OBJECTIVES: Identify the structure of the aircraft maintenance department. Describe the divisions of the intermediate and organizational levels of maintenance within the department. The aircraft maintenance department supports naval operations by the upkeep of aircraft and associated SE to the assigned level of maintenance. This support is accomplished by complying with the Naval Aviation Maintenance Program (NAMP), OPNAVINST 4790.2. Since all maintenance activities have similarities in mission, operation, and administration, these areas have standardized organization and administration. A maintenance department aids in improving the following areas: Performance and training of maintenance personnel Aircraft, equipment, and system readiness Maintenance integrity and effectiveness for all material Safety Usage of maintenance manpower and materials Planning and scheduling of maintenance work Management and evaluation of work performance Quality of the end product Attainment and retention of combat readiness Continuity when aircraft or personnel are transferred between commands All personnel engaged in maintenance tasks work toward a common goal of assuring achievement in the above areas. They work under the management control process used in the aircraft maintenance department organization. 1-4

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Some of the functions of an aircraft maintenance department are as follows: Periodic maintenance and routine inspection and servicing of aircraft, associated SE, and aeronautical material and components. Maintenance and inspection include the necessary disassembly, cleaning, examination, repair, modification, test, inspection, assembly, and preservation. Special work (when required) to comply with TDs or local instructions. On the other hand, a staff relationship (normally shown by a solid horizontal line feeding into the main arteries of the organizational chart) exists between an advisory staff supervisor and a production line supervisor. The sole concern of staff personnel is to service and support the production effort. Management Correction of aircraft and equipment discrepancies. Assurance of high quality in all work. Maintenance of required records and technical publications. Maintenance and custody of tools and other equipment provided the activity for its own use. Management exercises the authority and takes the responsibility for the performance of the mission, tasks, and work of the maintenance department. The organizational structure lets the aircraft maintenance officer (AMO) (with the aid of subordinate officers) manage the maintenance department. The AMO is responsible to the commanding officer for the accomplishment of the department’s mission. The AMO directs the maintenance department according to directives from higher authority. Training of assigned personnel. Conducting maintenance and ground-handling safety programs. Submission of reports for statistical, analytical, and historical purposes. The depth and complexity of specific functions vary with the number and type of aircraft involved and the assigned maintenance level. This chapter covers the aircraft maintenance organizations for the 0- and I-level maintenance activities. You will probably be assigned to an activity that performs only 0- or I-level maintenance. The functional management responsibilities assigned to the AMO are planning, control, and production. Also, the AMO estimates and programs facilities, equipment, manpower, and training requirements. With subordinate maintenance department officers, the AMO provides direction and guidance to subordinate divisions. The subordinate divisions implement and comply with all local- and higher-authority maintenance policies and technical directives. Normally, the following subordinate officers assist the AMO in the management of the maintenance department: Organizational Structure Relationships Assistant aircraft maintenance officer. This officer ensures that the staff divisions conform to established policies involving quality assurance and supervises maintenance administration and department training. The organizational structure of aircraft main- tenance activities uses the principles and concepts of modern management. This structure incorporates the basic aspects of organizing-pinpointing responsibilities, span of control, alignment of functions, division of work, uniformity of assignments, and delegation of authority commensurate with the assignment of responsibility. Maintenance material control officer. This officer is directly responsible to the AMO for the overall productive effort and material support of the department, Aircraft maintenance division and branch officers. These officers organize and manage their respective divisions and branches. A line relationship (normally shown by a solid Specific responsibilities of these officers are vertical line on an organizational chart) is a outlined in OPNAVINST 4790.2. The organization of relationship that exists between a superior and the maintenance department provides firm lines of subordinate within both staff and line segments of the authority from the AMO to the personnel who do the organization. This relationship involves the direct work for which the department is responsible. Major supervisory functions of assigning work to segments, called divisions, of the department report subordinates and appraisal of performance. directly to the department head. Several branches 1-5

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report to each division and at the lowest organizational level, sections report to each branch. Q17. Q18. Q19. Q20. Q21. Q22. Q23. What is a "line" relationship? A relationship that exists between an advisory staff supervisor and a production line supervisor is known as what type of relationship? Who is responsible to the commanding officer for the accomplishment of the maintenance department’s mission? What are the functional management responsibilities of the aircraft maintenance officer? What subordinate officers assist the aircraft maintenance officer in the management of the maintenance department? What officer is responsible for ensuring that staff divisions conform to established policies? In addition to material support, what is the maintenance material control officer's direct responsibiliy? Organizational Level (O-Level) Organizational maintenance activities (OMAs) are the main users and operators of naval aircraft. Therefore, most of their maintenance tasks are the day-to-day support for their own operations. OMAs have maintenance managers who manage the activity, staff divisions that perform support-type functions for the production elements, and production divisions that actually perform the various maintenance tasks. Figure 1-1 shows the organization chart of the different work centers in an O-level maintenance department. Typical work centers are maintenance control. the power plants branch of the aircraft division. and the electronics branch of the avionics/armament division. STAFF DIVISIONS.—At OMAs, staff divisions provide services and support to the production divisions. Maintenance administration and quality assurance (QA) divisions link the progress of the production divisions. Together. they provide the AMO with a view of the current status of the maintenance Figure 1-1.—O-level maintenance department organization. 1-6

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department. In this section, you will be introduced to the staffdivisions and their duties and responsibilities. Maintenance Administration. —The main- tenance administration provides administrative services for the maintenance department. It prepares maintenance-related correspondence that requires special attention by the AMO or higher authority; maintains files of maintenance-related correspondence and nontechnical publications and instructions; and ensures distribution of incoming messages, correspondence, and other data, including official and personal mail. It also coordinates department administrative security responsibilities with other departments and divisions; and maintains personnel assignment records for the department. Quality Assurance.—The idea of QA is to prevent defects from occurring from the start of a maintenance operation to its finish. QA is the responsibility of all personnel. Its achievement depends upon prevention, knowledge, and special skills. Prevention is making sure that there are no maintenance failures. It extends to the safety of personnel, to the maintenance equipment, and to all aspects of the total maintenance effort. Prevention allows you to regulate events. rather than have them regulate you. Knowledge is factual information. It includes data collection and analysis for acquiring knowledge to prevent defects. Special skills are required of a staff of trained personnel for the analysis of data and supervision of QA. The objective of QA is to readily pinpoint problem areas so that management can accomplish the following: Improve the quality, uniformity, and reliability of the total maintenance effort Improve the work environment, tools, and equipment used in the maintenance effort Eliminate unnecessary man-hour and dollar expenditures Improve training, work habits, and procedures of maintenance personnel Increase the excellence and value of reports and correspondence originated by maintenance personnel Effectively disseminate technical information Establish realistic material and equipment requirements in support of the maintenance effort Effectively support the Naval Aviation Maintenance Discrepancy Reporting Program (NAMDRP) Support the Foreign Object Damage (FOD) Prevention and Reporting Program Normally, QA work spaces are near the production divisions and the AMO. System Administrator/Analysis.—The system administrator/analyst (SA/A) provides analytical information for the AMO’s review of management practices within the organization. An SA/A will be established in O-level activities to monitor, control, and apply the MDS within that activity. The SA/A serves as a point of contact between work centers and the data services facility (DSF), and is responsible for all aspects of the maintenance data system (MDS), including Naval Aviation Logistics Command Management Information System (NALCOMIS) reports and inquiries. If an activity is operating with VIDS, the analyst will be assigned to QA/A. The requirements for analysis stem from many sources and apply to a wide range of maintenance subjects. At times, analysis is initiated to provide an answer to a specific problem. At other times, analysis of selected areas of maintenance may be initiated by a monitoring action. Some of the more important responsibilities of the SA/A are as follows: Coordinate and monitor the MDS/NALCOMIS for the department. Review maintenance data reports(MDRs) to identify trends. Use the MDWNALCOMIS to assist in identifying possible deficiencies in technical training or documentation procedures. Monitor the assignment of the third position of work center codes. Collect, maintain, and distribute in narrative, tabular, or chart or graph form the data required to monitor, plan, schedule, and control the maintenance effort. Develop charts, graphs, and displays for command presentation. Assist the AMO and other supervisory personnel in determining the specific goals for new types of data reports required for managing the maintenance effort. 1-7

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Identify and apply analytical techniques to areas of material deficiencies, high man-hour consumption. or other pertinent trends. Provide assistance to production control or maintenance/material control in determining material consumption and usage based on MDS or NALCOMIS reports and inquiries. Coordinate all MDR matters with the DSF. MAINTENANCE MATERIAL CONTROL. — The maintenance material control officer (MMCO) exercises authority in a line position between the AMO and the production divisions. The MMCO is directly responsible to the AM0 for the overall productive effort and material support of the department. Maintenance material control normally has two work areas-one for maintenance control and one for material control. Maintenance Control Work Center. —The maintenance control work center is usually referred to as maintenance control or the maintenance control office. Maintenance personnel use these terms interchangeably,. Maintenance control is the nerve center of the maintenance department. The MMCO is its head. This officer, assisted by the maintenance control chief. directs the production divisions. He or she makes sure there is prompt movement of aircraft, parts. and materials. The MMCO also maintains liaison with the supporting activity to ensure that the department’s workload requirements and productive capability are compatible. Under his or her direction maintenance control personnel plan, schedule. and provide positive control of all maintenance performed on or in support of assigned aircraft. Material Control Center. —Material control center personnel provide material and supply support to the department. An effective aircraft maintenance department program depends upon a cooperative working relationship between production and supply. In the organizational maintenance department. the material control center acts as a liaison between the maintenance department and the local supply activity,. Personnel in the material control center make sure that the proper parts, tools, and equipment are available to the production divisions in the required quantity and at the proper time. Material control center personnel compile and analyze maintenance usage data. They furnish technical advice and information to the local supply activity on the identity and quantity of supplies. spare parts. and materials necessary for the assigned workload. 1-8 PRODUCTION DIVISIONS. —Aviation mechanics and technicians maintain naval aircraft and staff the production divisions. The production element of an O-level maintenance activity consists of the four divisions shown in figure 1-1. They may be subdivided into branches and sections to perform the required maintenance tasks more effectively. A discussion of the more important production divisions is presented in the following paragraphs. Remotely Piloted Vehicle (RPV) Division. —An RPV division (previously Target Division) is optional, and may be established when responsibilities concerning the operation and maintenance of aerial or surface targets are extensive. The RPV division coordinates and completes periodic maintenance, inspections, decontaminations, and rehabilitation of assigned RPVs. Aircraft Division. —The aircraft division has several branches. The power plants branch is manned by Aviation Machinist’s Mates (ADS), who maintain aircraft power plants and their related systems and components. The airframes branch is manned by Aviation Structural Mechanics (AMHs-Hydraulics and AMSs-Structures), who maintain the structural systems of the aircraft, landing gear, fuselage, etc. The aviation life support systems branch is manned by Aircrew Survival Equipmentmen (PRs) and Aviation Structural Mechanics (AMES-Safety Equipment). PRs maintain parachutes, life rafts, emergency equipment kits, and flight clothing. AMES maintain oxygen, pressurization, air-conditioning systems, and other emergency equipment. The inspection branch is headed by an inspection supervisor who performs all maintenance control functions (except cannibalization) of aircraft undergoing a phase inspection. NOTE: Many commands have a permanent inspection work center that has one person of each rating assigned, as necessary, for the inspection process. In some activities, a temporary crew may be established. NOTE: All work centers have a responsibility for corrosion. Additionally, most activities may have a permanent corrosion work center staffed by personnel from several ratings. Avionics/Armament Division. —The avionics/ armament division has several branches. The electronics branch is normally manned by Aviation Electronics Technicians (AT[O]s) who perform organizational-level preventive and corrective

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maintenance on aviation electronics systems, including communication, radar, navigation, antisubmarine warfare sensors, electronic warfare, data link, fire control, tactical displays, and associated equipment. The electrical and instrument branch, staffed by Aviation Electrician’s Mates (AEs), maintains the batteries and aircraft electrical and instrument systems. The armament branch is manned by Aviation Ordnancemen (AOs) who maintain armament and ordnance-related equipment. Q24. Q25. Q26. Q27. Q28. Q29. Q30. What is the concept of quality assurance? The achievement of quality assurance depends on what factors? What is the purpose of the system administrator/analyst at the organizational maintenance level? Who has the responsibility, as well as many other responsibilities, to identify material deficiencies and high man-hour consumption trends? What work center plans, schedules, andprovides positive control of all maintenance performed on or in support of the activities assigned aircraft? What branches or work centers make up the aircraft division? The avionics/armament division consists of what work centers? Line Division.—Personnel from many different aviation ratings normally man the line division. Personnel who are assigned to the line division might be aviation machinist’s mates, structural mechanics, electricians mates, or even personnel who are striking for the Aviation Storekeeper (AK) and Aviation Maintenance Administrationman (AZ) clerical ratings. This is the division to which you will probably be assigned first. Here, you will be introduced to the types of aircraft that are flown in your squadron. Chapter 5 of this TRAMAN covers the line division in detail. Intermediate Maintenance (I-Level) The primary mission of I-level maintenance is to enhance and sustain the combat readiness and mission capability of supported activities. I-level maintenance does this by providing quality and timely material support at the nearest location with the lowest practical resource expenditure. I-level maintenance is usually performed in a centrally located area in support of operating aircraft on shore stations, aboard ships, or within designated areas. Intermediate maintenance activities (IMAs) are not assigned aircraft for operational purposes. They concentrate their efforts on repairing and testing aircraft components. The organizational structure of the IMA is similar to the organizational structure of the OMA. But, because the IMA is larger than the OMA, it has more divisions. The I-level maintenance organization is made up of maintenance managers, staff divisions, and production divisions, which are shown in figure 1-2. Figure 1-2.—Intermediate-level maintenance department organization (ashore). 1-9

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STAFF DIVISIONS.—The staff divisions of the I-level maintenance department provide services and support to the production elements. They serve in much the same way as the QA division and maintenance administration division of an O-level activity. The administration division functions as the coordinator for all records and reports, directives, correspondence, and personnel matters for the department. Personnel in the I-level administration division perform the following duties: Conduct liaison with the administrative department regarding department personnel Safeguard and distribute personal mail to department personnel, when appropriate Control the classified matter required by the department Distribute approved locally issued reports and studies Coordinate transportation and communication requirements for their department Establish and coordinate the department training requirements. and obtain any school quotas needed to support these requirements Assign spaces to the various divisions, and establish the responsibility for security and cleanliness of such spaces Assume the responsibility for the cleanliness and security of vacant or unassigned maintenance spaces Arrange department participation in joint inspections of facilities assigned to tenant activities, especially incident to the arrival or departure of a tenant activity The QA division of I-level maintenance activities has the same primary functions as those of organizational activities—to prevent the occurrence of defects. Personnel in this division use statistical analysis to compare the results obtained with the results desired. Through research, they find methods of improving effectiveness of the overall maintenance effort. The objectives of the QA division in I-level maintenance are identical to the objectives of QA in O-level maintenance activities. MAINTENANCE MATERIAL CONTROL. — In an intermediate activity, maintenance material control is organized much like the maintenance material control of the organizational activity. It has two work centers-production control and material control. Production control is the central point of the entire maintenance effort. IMAs exist to support operating activities. Personnel working in the production control work center plan and schedule the workload. The workload consists of repairing, testing, and processing aircraft parts, components, and related equipment. Intermediate activities tend to be large. Because of this tendency, the location ofvarious work centers, and the number of components handled daily, it is not practical to control each component inducted from a central production control area. Production control delegates some of its functions to certain selected production divisions. These divisions are responsible to production control for the production efforts of their assigned work centers, scheduling components into work centers, and assigning priorities as directed by production control. The maintenance data base administrator/analyst (MDBA/A) provides qualitative and quantitative analytical information to the AM0 via the MMCO for continuous review of management practices within the department or activity The MDBA/A is established at the I-level to monitor, control, and apply the MDS. The MDBA/A also serves as a contact point between work centers and the DSF, and is responsible for the management of all aspects of the MDS including NALCOMIS reports and inquiries at the l-level. Specific responsibilities of the MDBA/A are parallel to that of the SA/A at the O-level. If an activity is operating with VIDS, the analyst will be assigned to QA/A. Production control cooperates with staffmembers. It uses staff findings and recommendations to improve the overall maintenance effort. Together with the administration division, the QA division and the MDBA/A, maintenance material control provides the intermediate aircraft maintenance officer with a complete picture of the maintenance situation for any given time, and also makes recommendations for improvement. The material control center coordinates and controls the supply functions of the department. It acts as a liaison between the department and the local supply, activity. It processes all supply and material transactions for the other divisions of the department. Other functions of the material control center are as follows: Requisitions material l-10

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Maintains the material control register Maintains inventories of materials on hand Maintains subcustody records for accountable items held by the department Maintains records of all material transactions and accounts for the expenditures of funds by the department Furnishes technical advice and information to the local supply activity concerning material requirements for the assigned workload In IMAs, the material control center has an aeronautical material screening unit (AMSU). This unit coordinates the screening of received materials and parts to determine the status and repair responsibility and capability. PRODUCTION DIVISIONS. —Normally, the l-level maintenance organization consists of six production divisions, as shown in figure 1-2. The six production divisions are power plants, airframes, avionics, armament equipment, aviation life support equipment, and support equipment. In this chart you can see that if the OMD and IMA are combined, an organizational maintenance division is established. Additionally, a support services division may also be established if so desired. However, this discussion deals with the six normal production divisions and their responsibilities, minus organizational maintenance and support services divisions. The type of work that you will perform is the same regardless of the maintenance level at which you are working. If you are an AD, you will work on engines. If you are an AE, you will work on instruments and electrical equipment. If you are an AT, you will work on avionics equipment. However, the work that you will perform is at a level beyond the capability of the supported activity. In this section, the more important responsibilities and functions of these divisions are presented. Power Plants. ADS staff the power plants division. They perform maintenance on power plants, power plant components, and associated systems. Airframes. AMs are assigned to work centers in the airframes division. The airframes division is responsible for the specified level of maintenance for the airframe and structural components; moveable structures and surfaces, including their hydraulic and pneumatic control and actuating systems and mechanisms; air-conditioning, pressurization, visual improvement, oxygen, and other utility systems; and seat and canopy ejection systems and components. Avionics. The avionics division is staffed with the appropriate combination of ratings to provide maintenance of avionics equipment for the supported activities: AEs maintain aircraft electrical and instrument systems. AT(I)s perform intermediate- level preventive and corrective maintenance on aviation electronic components supported by conventional and automatic test equipment, including repair of weapons replaceable assemblies (WRA) and shop replaceable assemblies (SRA). The AT also performs microminiature (2M) component repair, and performs test equipment qualification and associated test bench preventive and corrective maintenance. Armament Equipment. AOs are assigned to the armament division. They maintain aircraft armament equipment and aviation ordnance equipment. Aviation Life Support Equipment. PRs are assigned to the aviation life support equipment division. This division is responsible for intermediate maintenance in connection with parachutes, life rafts, pressure suits, oxygen masks, emergency equipment kits, flight clothing, oxygen regulators, automatic parachute actuators, and aviators’ protective helmets, etc. AME personnel also may be assigned to this division for upkeep and support of the oxygen system, pressurization and air-conditioning systems, and other emergency equipment as assigned within the scope of that rating. Support Equipment (SE). The Aviation Support Equipment Technician (AS) performs the necessary maintenance on the SE assigned to the maintenance department and supported activities. SE includes such items as test stands, workstands, mobile electric power plants, and pneumatic and hydraulic servicing equipment. Q31. Q32. Q33. What is the purpose of the production control work center? At the intermediate maintenance activity, who provides qualitative and quantitative analytical information to the AMO? At the I-level, power plants, airframes, avionics, armament equipment, support equipment, and aviators’ life support equipment are known as what type of divisions? 1-11

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NAVAL AVIATION LOGISTICS COMMAND MANAGEMENT INFORMATION SYSTEM (NALCOMIS) LEARNING OBJECTIVE: Define the purpose of the Naval Aviation Logistics Command Management Information System (NALCOMIS) NALCOMIS provides OMA, IMA, and aviation supply department (ASD) activities with a modern, real time, responsive, computer-based management information system. This automation helps us do our jobs better and more efficiently by reducing paperwork. NALCOMIS is not available at all aviation commands. If your command has not yet implemented NALCOMIS, then VIDS/MAFs will still be the means of performing and tracking maintenance. There are three basic objectives of NALCOMIS. To increase aircraft readiness by providing focal maintenance and supply managers with timely and accurate information required in their day-to-day management and decision-making process To reduce the administrative burden of the fleet To improve the quality of up-line reported data Figure 1-3 shows a NALCOMIS generated repair document. The information offered and data fields are the same as a VIDS/MAF; however, Conversation codes are used to input information. OPNAVINST 4790.2. Vol III, offers more detailed information on the NALCOMIS system. NOTE: NALCOMIS specific documentation procedures, input formats, and output formats are contained in the NALCOMIS End User Manuals for OMA, System Administrator (SA) Manual for OMA, Security Feature User’s Guide for OMA, NALCOMIS IMA Desk Top Reference Guides, and the NALCOMIS IMA User’s Manual. Q33. What is the purpose of NALCOMlS? Q35. What are the three basic objectives of NALCOMIS? Q36. If an I- or O-level activity does not yet operate under NALCOMIS, under what system do they document their maintenance? VISUAL INFORMATION DISPLAY SYSTEM (VIDS) BOARD LEARNING OBJECTIVES: Define the purpose of the Visual Information Display System board in aircraft maintenance. Identify the flow of a Visual Information Display System/Maintenance Action Form (VIDS/MAF) at the organizational and intermediate levels of maintenance. All maintenance managers have the responsibility to manage their resources efficiently. To do this, they must maintain control of the different elements within their area of responsibility. Effective control depends upon the availability of status information on these elements. The VIDS provides this information. Communication between maintenance control, work centers, and material control is important to make sure the VIDS operation is successful. To record this communication, we use VIDS boards and VIDS forms, which are discussed in the following paragraphs. O-LEVEL VIDS BOARD In the work center, the VIDS board is set up like the VIDS board shown in figure 1-4. This is a 25-pocket board. Most work centers can show all the necessary information on a board of this size. However, the number of aircraft and systems determines the number and size of boards that a work center needs. If work is shown by personnel assignment, the number of people assigned determines the size and number of VIDS boards used in the work center. The work centers should verify their VIDS boards with the maintenance control VIDS board at least once a day. Q37. What element is important to ensure successful operation of the Visual Information Display System (VIDS)? Q38. With regard to the VIDS board, what action should take place with maintenance control on a daily basis? Information Displayed Some of the types of information that can be shown on the VIDS board include personal history and information cards, personnel training inserts, and SE required by the work center. The personal history and information cards are placed in the far left-hand side of the board, if the work center is using the bureau/side 1-12

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Figure 1-3.—NALCOMIS Repair Document. 1-13

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Figure 1-4.—O-level work center VIDS board. (fig. 1-5) versus the personnel assignment (fig. 1-6) number method. The personnel training insert is put on the right side of the board to show the individual’s level of training on different systems. SE required by the work center may be shown on the bottom pocket NOTE: VIDS boards are not required to be set up exactly as shown in this chapter. However, In Work, Awaiting Maintenance (AWM), and Awaiting Parts (AWP) must be visually shown. There are two forms that are displayed on the VIDS board. They show the status of a weapon system or a repairable component. 1. VIDS/MAF MAINTENANCE ACTION FORM (OPNAV 4790/60). This form documents maintenance actions involving failed material. 2. SIGNAL TABS. Different color signal tabs show special priorities, conditions, or requirements. Signal tabs provide information necessary for the assignment of work and overall production. Some of the specific uses of signal tabs are shown below. Red. Not Mission Capable Supply (NMCS). Blue. Partial Mission Capable Supply (PMCS). Yellow. SE down. 1-14

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Figure 1-5.—Organizational VIDS board (bureau/side number method). Figure 1-6.—Organizational VIDS board (personnel assignment number method). Orange. SE partially down. Green. Personnel shortage. A green signal tab indicates that the personnel required to maintain a particular system are not available because they are on leave or have temporary duty requirements. VIDS Operating Procedures In this section, you will see how maintenance control uses the VIDS board. While reading this section, you should refer to figure 1-7. Maintenance l-15

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control receives discrepancies from sources such as pilots, aircrews, and maintenance personnel; or maintenance control might initiate a directed discrepancy (such as cannibalization). After maintenance control completes their required blocks of the VIDS/MAF, they forward copies 1 and 5 to the Work center for discrepancies found on the aircraft or SE. The work center places copies 1 and 5 on the VIDS board under the applicable column (AWM or In Work), as directed by maintenance control. Any time the status of a discrepancy changes (for example, has been In Work and goes to AWP status or back to AWM status). maintenance control must be notified immediately. Maintenance control must be in control of all maintenance at all times. The VIDS/MAF should always be kept in the appropriate column, both in the work center and maintenance control. Often a replacement part is required. To show Work stoppage for parts, mark the VIDS/MAF with the correct information in the H-Z Failed/Required project code from maintenance control and advise material control of the parts requirement. Finally, move the VIDS/MAF to the AWP column of the VIDS board. When the replacement part is received, the In Work or AWM status is entered, as appropriate, on the VIDS/MAF in addition to the date received in Block B53. If maintenance control authorizes the work to be started, the VIDS/MAF is moved to the In Work column of the VIDS board. NOTE: A discrepancy may go through the AWM, In-Work, and AWP process many times before it is corrected. If so, follow the above steps each time the status of a discrepancy changes. VIDS/MAF Flow Figure 1-7 shows the VIDS/MAF flow throughout the maintenance effort. Maintenance control is notified when all corrective actions have been completed. QA must be notified if any QA inspections or check flight requirements are needed as a result of material section. Then, obtain a supply priority and the maintenance actions. Figure 1-7.—Organizational maintenance (O-level) VIDS/MAF document flow chart. 1-16

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At this time, all necessary actions should have been made on the VIDS/MAF. The completed copy 5 is filed in a temporary file in the work center. When the supervisor signs the VIDS/MAF, it means that the maintenance action is complete, that tool control inventories have been conducted at the proper intervals, that QA measures have been met, and that the documentation is complete and correct. Copy 1 of the completed VIDS/MAF is forwarded to maintenance control. After verification of the work center’s copy 5 with the VIDS/MAF copy 1 Daily Audit Report, copy 5 is maintained or destroyed, as required by local command policy. Q39. Upon initiation of a VIDS/MAF at the organizational level, which copies are forwarded to the work center? Q40. What must be done if a maintenance action results in the requirement of a check flight? Q41. Upon the completion of a maintenance action and when the VIDS/MAF is completed, which copy is forwarded to maintenance control? I-LEVEL VIDS BOARD A visual display of all current weapons systems or repairable component status is as necessary at the I-level of maintenance as it was at the O-level of maintenance. The VIDS/MAF flow for the I-level is shown in figure 1-8. The same forms are used at this level—VIDS/MAF and signal tabs. Information Displayed VIDS/MAFs are used at the I-level of maintenance in the same way that they are used at the O-level of maintenance. The VIDS/MAF is used to report maintenance repair actions. The signal tabs are used in much the same way at I- and O-level maintenance, but with the following differences: Orange. Bench/equipment inoperable Yellow. Bench/equipment partially capable Green. Local Repair Cycle Asset (LRCA) at low level Blue. LRCA at zero level (critical) Red. Expeditious repair Figure 1-8.—I-level maintenance VIDS/MAF document flow chart. 1-17

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VIDS Operating Procedures The supervisor’s signature on the VIDS/MAF means that the following actions have been taken: The work center receives copies 1, 4, and 5 of the VIDS/MAF with the nonready-for-issue (non-RFI) component. The work center supervisor puts copy 5 on the work center VIDS board in the pocket next to the applicable work unit code (WUC)/LRCA number/part number/name under the In-Work column. Copies 1 and 4 are kept with the inducted equipment throughout the maintenance cycle. If the job is not assigned by production control, copy 5 is placed under the AWM column. Any status changes, such as from In Work to AWP or In Work to AWM, must be reported to production control. Copy 5 is then placed under the correct column of the work center VIDS board. When a component goes to an AWP status and after appropriate entries have been made on the VIDS/MAF, that component should be packaged and preserved. Then, it is sent to the AWP unit or its equivalent. Copies 1 and 4 of the VIDS/MAF stay with the component. Copy 5 of the VIDSMAF is moved to the AWP column of the work center VIDS board. When the component is in a ready for issue (RFI) or beyond capability of maintenance (BCM) condition, the necessary entries are made on all copies of the VIDSMAF (including date). Copy 5 is placed in a temporary file until it is verified against the daily audit report (DAR). Components that are BCM have the Type Equipment code and job control number (JCN) entered in the Remarks block of the attached Material Condition Tag (DD Form 1577-2/1577-3). Maintenance actions have been completed. Too! control inventories have been held at the appropriate times. The component has been adequately preserved and secured for routing to the AMSU. Documentation is correct. QA measures have been met. The work center supervisor is also responsible for maintaining the work center’s VIDS board. As shown in figures 1-9 and l-10, this board provides the status for In-Work, AWM, and AWP components by WUC, pool index number, or part number within the work center. NOTE: It is not mandatory that the VIDS boards be set up exactly as they are shown in this chapter. However, In-Work, AWM, and AWP must be visually shown by WUC, pool index, or part number at the I-level of maintenance. The production control supervisor should establish a schedule to make sure that a!! work centers verify the production control VIDS board at least daily. Q42. What does a red signal tab on an I-level VIDS board or VIDS/MAF indicate? Q33. Upon induction of a non-RFI component to an I-level activity, where are copies 1, 4. and 5 of the VIDS/MIF routed? Figure 1-9.—Work center 610 VIDS board. 1-18

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Figure 1-10.—Work center 630 VIDS board. Q33. At the I-level, what happens to a repairable component for which parts have been ordered? ADMINISTRATIVE FORMS AND DOCUMENTS LEARNING OBJECTIVE: Identify the forms and documents used in the maintenance administration section, their purpose, and use. The Aviation 3-M Maintenance Data System (MDS) provides a mechanized collection and processing of statistical data. This is essential to the management of resources. The maintenance worker records most of this data on prescribed forms. As a mechanic or technician, you will be required to initiate or complete various forms. A brief description of some of these forms and related data is given in the following text. For more detailed instructions on filling out these forms, refer to OPNAVINST 4790.2. Personnel having responsibilities under NALCOMIS should refer to the NALCOMIS User’s Manual. DATA ACCURACY Accurate documentation is necessary. Each MDS document that is not correct causes a loss of effectiveness of the data and of the system in general. The data must be accurate and complete because it has Navy-wide application. VIDS/MAINTENANCE ACTION FORM (MAF) O- and I-level maintenance activities use the VIDS/MAF, OPNAV 4790/60 (fig. 1-11), or NALCOMIS to report on equipment maintenance actions. They also use one of the two methods to document the removal and processing of a repairable component or item to AIMD. For the VIDS/MAF, copies 1, 3, 4, and 5 of the form contain the same information. Copy 2 is a tear-out that contains the necessary data for material reporting. Copy 3 is perforated along the fold line to make it easier to fold the form for insertion in the VIDS board or to permit removal of the top part of the form. Carbons separate all of the copies so that the coded information carries through to each copy of the form. At the O-level of maintenance, copies of the VIDS/MAF are used and distributed as follows: Copy 1—work center register, control, and processing copy Copy 2—QA suspense file copy Copy 3—maintenance control register Copy 4—aircraft discrepancy book (right side) copy Copy 5—work center MDR verification copy At the I-level of maintenance, copies of the VIDSMAF are used and distributed as follows: l-19

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Figure 1-11.—Visual Information Display System/Maintenance Action Form (VIDS/MAF). 1-20

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Copy 1—work center register, control, and processing copy Copy 2—supply department VIDS copy Copy 3—production control register Copy 4—RFI/BCM copy Copy 5—work center MDR verification copy The VIDSMAF documents the following types of maintenance actions and accumulates data for reports that establish supply and manpower requirements: Maintenance actions: Repair work on the equipment that does not involve removal of defective or suspected defective repairable components. The portion of a special, conditional, corrosion, periodic, phase, acceptance, or transfer inspection that involves the search for defects. This portion is commonly known as the look phase. Removal of components for check, test, inspection, and service actions. Removal and replacement of an item for cannibalization purposes. Removal or installation of items/components for mission configuration changes as designated by the ACC. Incorporation of TD changes and associated maintenance actions. Removal and replacement of repairable components within end items. Subsystem Capability and Impact Reporting (SCIR) data. Fix-in-place actions discovered during inspections. Supply/manpower reports: Man-hours accumulated during work stoppage for parts or maintenance. Accumulated man-hours during or at the end of a reporting period for a job not completed, where required by the ACC. Assistance from work centers in support of a basic work center. Support of a repairable item being processed through an IMA. Troubleshooting man-hours. Ordering and issuing of repairable components, subassemblies, and parts. Accumulated man-hours on jobs closed out due to an aircraft accident. Documentation of preservation or depreservation. The MAF flow under NALCOMIS varies slightly from that of a VIDS/MAFS. Upon origination of a discrepancy, only two copies of the MAF are printed and, as the discrepancy is repaired, it is updated electronically. The complete process for OMA and IMA are outlined in OPNAVINST 4790.2. Q45. What is the result of inaccurate or incomplete information documented in the Maintenance Data System (MDS)? Q46. At both the I and O levels of maintenance, what is the purpose of NALCOMIS or VIDS/MAFS? Q47. What is the "look phase" of an inspection? MACHINE REPORTS O- and I-level maintenance supervisors regularly use the daily and monthly MDRs described in this section. OPNAVINST 4790.2 lists all of the MDRs available from the DSF and their uses. VIDS/MAF Copy 1 Daily Audit Report This report is for the work center supervisor. It is designed to validate the previous day’s VIDS/MAF copy 1 submissions. DARs should be verified daily, corrections annotated, and returned to the analyst. The analyst will resubmit the corrected report with the following day’s data. NALCOMIS users should refer to the NALCOMIS User’s Manual for details on verification of data accuracy. Monthly Production Report (MDR-2) This report summarizes, by work center, all maintenance actions, TD compliance, and data entered in the Failed/Material block of the VIDS/MAF. CODES LEARNING OBJECTIVE: Recognize the codes used to document maintenance on NALCOMIS and the VIDS/MAF. 1-21

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Aircraft maintenance uses codes for processing information. Some information, such as the aircraft bureau number, is normally expressed in numerical terms; thus, it does not need to be converted into codes. In other cases. the information must be converted into code so it can be machine processed. Basic codes used on the VIDS/MAF are prescribed for Navy-wide use. Therefore, they cannot be changed at local option. Some of the codes are built to provide some flexibility to allow expansion to meet local needs. Some of the principal codes used by aircraft maintenance activities are described below. NOTE: A complete list of the codes can be found in an appendix to OPNAVINST 4790.2. Organization code. The organization code is a three-character. alphanumeric code that identifies an activity within a major command. Permanent Unit Code (PUC). The PUC is a six-character, numeric code assigned to each aircraft reporting custodian for identification. Work Center Code (WCC). The WCC is a three-character, numeric code that is used to identify work centers within an organization. Type Equipment code (TEC). The TEC is a four-character. alphabetic code that identifies the end item of equipment on which work is performed, such as aircraft, engine, or SE. Julian date. The Julian date is a four-character, numeric code used to show the date. The first character of the code is the last digit of the year, and the last three characters of the code show the day of the year. For example. Julian date 6324 is the 324th day of 1996, or November 19, 1996. When used on the VIDSMAF as part of the JCN, the first position (showing the year) is omitted. All dates used on source documents are shown in Julian dates. Job control number (JCN). The JCN is a 9-, 10-. or 11 -character. alphanumeric code used to separately identify each maintenance action. The JCN is made up of four parts: the Organization code. the three-character part of the Julian date that shows the day of the year, a sequence number, and a JCN suffix. The sequence number is either a three-character number that runs sequentially from 001 to 999 or a three-character, alphanumeric number with an alphabetic first character and the last two numbers running sequentially. from 00 to 99. Three-character. sequence numbers are used to identify routine day-to-day maintenance actions, such as AC4-324-216. Three-character, alphanumeric sequence numbers are used only to document major inspections other than preflight, postflight, turnaround, daily, special, conditional, corrosion, and acceptance/transfer inspections. An example of this type of JCN is AC4-324-A00. The JCN suffix is an alphanumeric code that is used by IMAs. It identifies a subassembly, or subassembly repair action completed separately from the major component repair action. This suffix is added to the basic JCN to create the fourth part. Work Unit Code (WUC). The WUC is a one-. three-, five-, or seven-character numeric or alphanumeric code. This code normally identifies the system, subsystem, set, component. and part of the end item being worked on. The first two characters identify the system and are standardized. Action Taken code. The Action Taken code is a one-character, alphabetic or numeric code that describes what maintenance was performed on an item identified by a Work Unit Code. Commercial and Government Entity (CAGE). This is a five-position code assigned to manufacturer’s and nonmanufacturer’s organizational entities and contractors of items procured by agencies of the Federal Government. This code is commonly called the Manufacturer‘s code. Malfunction Description code. The Malfunction Description code is a three-character, alphanumeric code used to describe the malfunction occurring on or in an end item. These codes are listed in both alphabetical and numerical sequence in all Work Unit Code manuals. Technical Directive code. The Technical Directive (TD) code is a 12- or 13-character code used to identify a specific TD by type number, revision, amendment, part, and kit number. This code applies to the VIDS/MAF when a TD compliance is documented. The first two characters of Technical Directive codes are listed in an appendix to OPNAVINST 4790.2. Technical Directive Status code. The Technical Directive Status code is a one-character. alphabetic or numeric code used to describe the type of work accomplished. The type of work refers to scheduled maintenance. unscheduled maintenance. and so forth. 1-22

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When Discovered code. The When Discovered code is a one-character, alphabetic code that identifies when the need for maintenance was discovered. Transaction code. The transaction code is a two-character, numeric code that shows the type of data being reported. Time/Cycle Prefix code. The Time/Cycle block is made up of a prefix and four numerical digits. The prefix indicates the source of time (usually in hours), cycles, or counts (rounds fired, number of catapult launches, or arrested landings). All entries in the Time/Cycle block are preceded by a prefix code. Some examples of these codes are as follows: A—indicates aircraft time and is used to report removal/installation of equipment not having an hourmeter installed or Aeronautical Equipment Service Record (AESR) or an SRC card maintained. E—indicates engine time (logbook time since overhaul). L—landings. M—indicates meter time. N—rounds fired. All entries in these blocks must be five digits. For example, report 27 hours type-equipment time as A0027. If the time exceeds 9,999 hours, record the last four digits only. For example, 10,231 hours would be recorded as A0231. Awaiting Maintenance Reason code (AWM). The AWM code is a one-digit, numeric code used to show the reason no maintenance is being performed. Q48. Q49. Q.50. Q51. Q52. Q53. Q54. What components create the Job Control Number (JCN)? What is indicated by a JCN suffix? What is a Work Unit Code (WUC)? What code describes the maintenance performed on an item identified by a WUC? What is the proper name for what most technicians refer to as the Manufacturer ’s code? What is a Malfunction code? How many positions complete the Time/Cycle block on a VIDS/MAF? SE RECORDS, FORMS, AND DOCUMENTS LEARNING OBJECTIVE: Identify the records, forms, and documents used for support equipment (SE) maintenance management and their purposes. Throughout the operational life of an end item of SE, many records, forms, and documents are generated for the support and management of that particular item. The following records, forms, and documents (which effect transfer of SE) are used to obtain and maintain the history of operation, maintenance, and configuration status. SE CUSTODY AND MAINTENANCE HISTORY RECORD, OPNAV 4790/51 This form is used to record acceptance information, custody and transfer, rework, preservation and depreservation, and TDs. It also includes a record of periodic maintenance performed by hours, starts, date completed, next PM due, activity and signature. It accompanies all items of SE that have formal periodic maintenance requirements; for example, MRCs, MIMs, handbook of service instructions, manufacturer’s handbook, and applicable TDs. Exceptions are precision measuring equipment (PME), engine test cells and stands, and GB1As (these items have their own records). However, those items of PME that have formal periodic maintenance requirements, in addition to calibration requirements, will require this form; for example, versatile avionics shop test (VAST) stations. Reporting custodians retain the latest completed copy, the current copy, and transcribe accumulated data on initiation of each new record (fig. 1-12). This form accompanies weapons and support equipment (WSE) to the weapons department when subcustodied from AIMD. You can find an example of the form, along with step-by-step instructions, in OPNAVINST 4790.2. Q55. Q56. Q57. What form is used to document preservation of support equipment? Are SE Custody and Maintenance History Records, OPNAV 4790/51, used to document rework maintenance on an engine test cell? Who retains the latest completed copy of the SE Custody and Maintenance History Record, OPNAV 4790/51? 1-23

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Figure 1-12.—SE Custody and Maintenance History Record, OPNAV 4790/51. SE PREOPERATIONAL RECORD, OPNAV FORM 1790/52 This form (fig. l-13) is maintained on the VIDS board cardex or filing container held by the work center responsible for performing preoperational inspections. The activity that has physical custody is responsible for required entries. Entries are made to reflect all preoperational inspections performed. The reporting custodian issues a new card when the card in use has been completely filled. THE MONTHLY MAINTENANCE PLAN LEARNING OBJECTIVE: Identify the purpose and applicability of the Monthly Maintenance Plan (MMP). The purpose and contents of the monthly maintenance plan (MMP) for O- and I-level maintenance activities are discussed in the following paragraphs. O-LEVEL MONTHLY MAINTENANCE PLAN The MMP provides scheduled control of the predictable maintenance workload. The predictable maintenance workload includes inspections, transfer and receipt of aircraft, and incorporation of TDs. By scheduling predictable maintenance, maintenance managers can determine their capability for doing unscheduled work. Additionally, maintenance managers can determine the requirements for SE, material, manpower, and any other factors affecting the maintenance operation in advance of the actual need. A monthly maintenance meeting is held within the maintenance department to finalize the MMP. The AMO presents the proposed MMP, and maintenance personnel discuss requirements, problems, support, and other factors involved in the maintenance effort. The AMO sets the format and the arrangement of the MMP. The MMP contains the following information: 1-24

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Figure 1-13.—SE Preoperational Record, OPNAV 4790/52. Projected known operational commitments, including the number of flights, flight hours, and aircraft use Date of scheduled inspections Schedule of preinspection meetings Dates of scheduled receipts or transfers of aircraft and type of work to be done on these aircraft PME calibration requirements Schedule of technical training Forced removal item (high time, and so forth) Technical directive compliance (TDC) Current list of QA personnel (QAR, CDQAR, CDI) Schedule of personnel for ejection seat safety checkout Date of scheduled SE inspections Schedule of nondestructive inspection (NDI) requirements The MMCO prepares and publishes the MMP for the AMO’s signature. The MMP is distributed by the 25th of the month prior to which it applies. For example, the MMP for April is distributed by the 25th of March. Maintenance supervisors within the activity, plus the supporting AIMD/IMA and the station/ship supply officer, know the contents of the MMP. AIMD/IMA MONTHLY MAINTENANCE PLAN The MMP is published by the AIMD/IMA for use by the production divisions. The AIMD/IMA officer holds a monthly meeting. Representatives of the maintenance and supply departments of all supported 1-25

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activities attend this meeting. A representative of the weapons department also attends the meeting. This meeting provides the planning and coordination needed to improve the overall maintenance program. Organizational maintenance representatives attend this meeting to discuss the quantity and type of support required. This includes a discussion about the contents of the organizational MMP. Squadron representatives discuss ail factors that affect the anticipated AIMD/IMA workload. This meeting is a tool used to plan the monthly maintenance schedule. The maintenance schedule is part of the MMP. The AIMD monthly maintenance plan is distributed by the last day, of the month prior to the month to which it applies. The following information is included in the MMP. A projected schedule of items to be inducted for check and test from supported squadrons and the supply activity Anticipated changes in the operational commitments of supported activities A schedule of technical training A schedule of maintenance requirements for shop-installed SE Other known or anticipated factors affecting the production effort of the IMA All known TD incorporation requirements A current list of QARs, CDQARs, and CDIs Identification of forced removal (high-time) components Weapons department inputs, which include the following: A projected schedule of armament weapons support equipment (AWSE) inspections, those items requiring test and check, and anticipated receipts or transfers; all known WSE TD incorporation requirements; and identification of known or anticipated AWSE end items or components to be returned to the AIMD for maintenance beyond the capability of the weapons department or for other reasons. Q58. What is the major provision of the Monthly Maintenance Plan? Q59. At the O level, when is the Monthly Maintenance Plan for March required to be distributed? Q60. Where can you find a list of current I-level collateral duty inspectors? MAINTENANCE TRAINING IMPROVEMENT PROGRAM (MTIP) LEARNING OBJECTIVE: Define the purpose of the Maintenance Training Improvement Program (MTIP) in aircraft maintenance. The Maintenance Training Improvement Program (MTIP) is an unclassified training management system which, through diagnostic testing procedures, identifies training deficiencies at both the O- and I-levels of maintenance. Through individual evaluation of technical knowledge levels, a qualitative assessment is made of existing training courses, materials, and community level skills. Such assessments point out corrective actions needed to enhance technical knowledge levels and to improve existing training courses. The Director of Air Warfare (N88) establishes policy and exercises overall control of the MTIP Program; however, the AMO or IMA maintenance officer ensures the MTIP program is conducted per ACC/TYCOM directives. Q61. What is the purpose of the Maintenance Training Improvement Program (MTIP)? SUMMARY This chapter discussed a variety of areas to include NAMP objectives, familiarization of O- and I-level maintenance, their structures, responsibilities, and rating applications, as well as a brief overview of the NALCOMIS program, VIDS/MAFs, SE records and forms, how they are used in the maintenance departments, and a brief description of MTIP. This volume of information is more than any one individual could memorize or be solely responsible for; therefore, you should refer to the applicable references when you need more information. Make sure you are informed of any changes affecting you or your work center. 1-26

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ANSWERS TO REVIEW QUESTIONS A1. Achieve and maintain maximum material readiness, safety and conservation of material in the maintenance of aircraft. A2. To maintain assigned aircraft in a state of full mission capability (FMC). A3. Rework and upkeep. A4. Rework maintenance. A5. Standard depot-level maintenance (SDLM). A6. Work done to aircraft, equipment, or support equipment to improve or change its capability to perform special functions. A 7. Operating units and SE activities. A8. Scheduled A9. Special upkeep or unscheduled maintenance. A10. Three. A11. Organizational, intermediate and depot. A12. Work performed by an operating activity on a day-to-day basis in support of its own operations. A13. Intermediate level. A14. Industrial type. A15. The CNO sponsors and directs the NAMP. A16 Naval Supply Systems Command (NAVSUP). A17. A relationship that exists between a superior and subordinate within both staff and line segments of the organization. A18. A staff relationship. A19. The aircraft maintenance offcer. A20. Planning, control, and production. A21. Assistant aircraft maintenance officer (AAMO), maintenance/material control officer (MMCO), and aircraft division and branch officers. A22. Assistant aircraft maintenance officer. A23. The overall productive effort of the maintenance department. A24. To prevent defects from occurring from the onset of a maintenance operation through its completion. A25. Prevention, knowledge, and special skills. A26. Monitor, control, and apply the Maintenance Data System within the activity. A27. System administrator/analyst. A28. Maintenance control. A29. Power Plants, airframes, and aviators life support systems (some activities also have an inspection or phase branch and a corrosion branch). 1-27

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A30. A31. A32. A33. A34. A35. A36. A37. A38. A39. A40. A41. A42. A43. A44. A45 A46. A47 A48. A49. A50. A51. A52 A53. Electronics branch, electrical and instrument branch, and the armament branch. Production control, the central point of the entire maintenance effort, plans and schedules the IMA’s workload. The maintenance data base administrator/analyst. Production divisions. NALCOMIS provides OMA, IMA and ASD activities with a modern. real time, responsive, computer based management information system. 1. To increase aircraft readiness by providing local maintenance and supply managers with timely and accurate information required in their day-to-day management and decision making process. 2. To reduce the administrative burden to the fleet. 3. To improve the quality of up-line reported data. Visual Information Display System (VIDS). Communication between maintenance/production control, workcenters, and material control. VIDS board verification. Copies 1 and 5 are forwarded to the work center. Notify quality assurance. Copy 1 of the VIDS/MAF is sent to maintenance control. The component inducted is expeditious repair. To the work center receiving the non-RFI component for repair. The component should be properly preserved, packaged and sent to the AWP unit managed by supply personnel. Loss of effectiveness of the data and the MDS in general. Documentation of on-equipment maintenance actions. The portion of a special, conditional, corrosion, periodic, phase, acceptance or transfer inspection that involves the search for defects. The organization code, the last three digits of the Julian date, and an activity assigned sequence number. A subassembly or subassembly repair action completed separately from the major component repair action. A one, three, five, or seven character numeric or alphanumeric code which identifies the system, subsystem, set, component or part of the end item being worked on. Action Taken Code. Commercial and Government Entity (CAGE). A three character, alphanumeric code used to describe the malfunction occurring on or in an end item. 1-28

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A54. A55. A56. A57. A58. A59. A60. A61. Five, a prefix and four numbers. SE Custody and Maintenance History Record, OPNAV 4790/51. No. Test cells have their own records. Reporting custodian. The MMP provides scheduled control of all predictable maintenance. By the 25th of February. The IMA Monthly Maintenance Plan. The MTIP identifies training deficiencies, at both the O and I levels of maintenance, through diagnostic testing procedures. 1-29

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CHAPTER 2 PUBLICATIONS In chapter 1, you were given an overview of the maintenance system, maintenance administration, Visual Information Display System/Maintenance Action Form (VIDS/MAF), and Naval Aviation Logistics Command Information System (NALCOMIS). In this chapter, you will learn about some of the publications that you will use to perform your duties. Good technical manuals are necessary to maintain modern weapons systems. The Navy’s combat readiness depends upon the quality of these publications and the knowledge and skill of maintenance personnel using them. Technical publications provide information and direction in your own technical language. They are prepared by the manufacturer of the specific aircraft model, engine, or equipment and by NAVAIRSYS- COM or its field activities, according to specifications issued by NAVAIRSYSCOM. The information contained in these manuals include the current, authoritative directions for material upkeep, check, test, repair, and operation. This provides for optimum product performance. All personnel responsible for the operation and maintenance of aircraft, engines, and associated equipment and systems must know how to use these publications. For more information concerning the technical manual program, refer to Naval Air Systems Command Technical Manual Program, NAVAIR 00-25-100, and OPNAV Application Guide and Index for Navy Standard Technical Manual Identification Numbering System, OPNAV N0000-00-IDX-000/TMINS. NAVAIR TECHNICAL MANUAL PROGRAM LEARNING OBJECTIVES: Define the purpose of technical publications. Identify the manual that outlines the management of the NAVAIR Technical Manual Program. Recognize the types, styles, and formats of NAVAIR technical publications. Recognize the systems used to identify technical manuals. Describe the means of updating technical manuals. The primary purpose of technical publications is to help you perform your assigned maintenance tasks. If you are to maintain complex weapons systems, you must be able to get the required information from technical manuals. The Department of Defense (DOD), the Department of the Navy (DON), and the Naval Air Systems Command (NAVAIRSYSCOM) work together to maintain and improve the quality of aeronautic technical publications. The NAVAIR 00-25-100 manual describes the NAVAIR Technical Manual Program and provides guidance on maintaining technical manuals. It covers such topics as audit/inventory, deficiency reporting, storage, establishing libraries, ordering, changes, and responsibilities for use within a command. It also covers the use of Army/Air Force publications in the NAVAIR system. All personnel in the aviation maintenance ratings use this manual to maintain and manage technical manuals. Q1. As a technician, if you are to maintain complex weapons systems, where must you obtain the required information? Q2. What manual provides guidance on maintaining technical manuals? TECHNICAL PUBLICATIONS Technical publications prepared for the NAVAIR technical publication system are presented in specific types, styles, and formats. You should be familiar with the basic types, styles, and formats, and their intended use. Types of Technical Manuals Technical manuals are divided into two major types, operational and maintenance. These manuals are the basic source of information for definition of operating instructions, tactical application, and the maintenance and upkeep of hardware. They are also the main support or reference for the training program. Operational Manuals. Operational manuals contain descriptions of weapons systems with instructions for their effective use. These manuals, such as the Naval Air Training and Operating 2-1

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time-consuming, and reduce equipment usage time. These problems can be avoided through good preventive maintenance practices and procedures. To have good preventive maintenance practices and procedures, you must know and be able to apply the common types of corrosion prevention and moisture protecting materials. Q1. How does corrosion endanger aircraft or reduce the margin of safety? Q2. All maintenance personnel must be formally Q3. trained in what program? What is the primary factor to consider when selecting materials for constructing an aircraft? on unpainted areas of working parts. Finally, shrouds, covers, caps, and other mechanical equipment provide varying degrees of protection from corrosive mediums. However, none of these procedures will provide 100-percent protection. Weathering causes paint to oxidize and decay. Sealants may be worked out by vibration or be eroded by rain and windblast. Preservatives offer only temporary protection when used on operating aircraft. The mechanical coverings can be installed improperly or negligently. Control of corrosion begins with an understanding of the causes and the nature of corrosion. Corrosion is CORROSION THEORY in its most familiar form is a reaction between metal and water, and is electrochemical in nature. the process of electrochemical or direct chemical attack on metals. The reaction is similar to that which occurs when acid is applied to bare metal. Corrosion LEARNING OBJECTIVES: Define the theory of corrosion and its process. Identify the publications and materials used in the prevention of corrosion. Metal corrosion is the decay of metals as they combine with oxygen to form metallic oxides. Corrosion is a chemical process that is the reverse of the process of smelting the metals from their ores. Very few metals are found in their pure state in nature. Most are found as metallic oxides. These oxides have other undesirable impurities in them. The refining process involves the extraction of the base metal from the ore. The base metal is then mixed with other elements (either metallic or nonmetallic) to form alloys. Alloying elements are added to base metals to develop a variety of useful properties. For instance. in aircraft structural applications, high strength-to-weight ratios are the most desirable properties of an alloy. After the base metals are refined, whether alloyed or not, they have a potential to return to their natural state. However, potential is not sufficient in itself to begin and promote this reversion; a corrosive environment must also exist. The significant element of the corrosive environment is oxygen. The process of oxidation (combining with oxygen) causes wood to rot or bum and metals to corrode. Control of corrosion depends upon maintaining a separation between susceptible alloys and the corrosive environment. This separation is accomplished in various ways. A good intact coat of paint provides most of the corrosion protection on naval aircraft. Sealants used at seams and joints prevent entry of moisture into the metal. Preservatives are used The electrochemical attack involves metals of different electrical potential. These metals do not have to be in direct contact. If one metal contains positively charged ions and the other negatively charged ions, all that is needed is an electrical conductor. When the conductor is present, current will flow between the two metals, as in the discharge of a dry-cell battery. In electrochemical corrosion, the electrical conductor may be any foreign material, such as water, dirt, grease, or any debris that is capable of acting as an electrolyte. The presence of salt in any of the foregoing mediums accelerates the current flow and increases the rate of corrosive attack. Once an electrical connection is made, the electron flow is established in the direction of the negatively charged metal (cathode). This action eventually destroys the positively charged metal (anode). Preventive measures include avoiding the establishment of the electrical circuit and removing corrosion as soon as possible to avoid serious damage. Figure 4-1 shows the electron flow in a corrosive Figure 4-1.—Simplified corrosion cell. 4-2

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environment destroying the anodic area. Note that the surface of a metal may contain anodic and cathodic areas because impurities or alloying constituents may have different potentials than the base metal. Electrochemical attack is evident in several forms. The form you find depends upon the metal involved, its size and shape, its specific functions, atmospheric conditions, and type of corrosion-producing agent (electrolyte) present. There are many factors that affect the type, speed, cause, and the seriousness of metal corrosion. Some of these factors you can control; others you cannot. Preventive maintenance factors, such as inspections, cleaning, painting, and preservation, are within the control of the operating squadron. They offer positive means of preventing corrosion. The electrochemical reaction, which causes metal to corrode, is more dangerous under wet, humid conditions than under dry conditions. The salt in seawater and the salt in the air are the largest single cause of aircraft corrosion. Hot climates speed the corrosion process because the electrochemical reaction develops fastest in a warm solution. The warm moisture in the air is usually enough to start corrosion of the metals if they are uncoated. As expected, hot, dry climates usually provide relief from constant corrosion problems. Extremely cold climates will produce corrosion problems when a salt-laden atmosphere is present. Melting snow or ice provides the necessary water to begin the electrochemical reaction. Thick structural sections are subject to corrosive attack because of possible variations in their composition, particularly if they were heat-treated during fabrication. Similarly, when large sections are machined or cut out after heat treatment, thinner sections have different physical characteristics than the thicker areas. Usually a difference in physical characteristics provides enough difference in electrical potential to make the piece highly susceptible to corrosion. Another factor relating to the size of materials is the relationship between dissimilar metals. (See figure 4-2.) If electrical contact develops between two dissimilar metals, the corrosion attack on the more active metal or anode (smaller size compared to the less active one) will be severe and extensive. See figure 4-2, bottom view. If the area of the less active metal is small compared to the other, anodic attack will be slight (fig. 4-2, top view). Corrosion on avionics equipment is a continuing process. The equipment does not have to be installed, operating, or exposed to a particularly harsh environment to corrode. The rate of the corrosion process is determined by the temperature, humidity, and chemicals in the environment. Moisture is the single largest contributor in avionics corrosion. It makes little difference whether the moisture is in the form of vapor or liquid. Its affects are detrimental to metals. A clean aircraft retains its aerodynamic efficiency and safety. Serious damage to the exterior and interior surfaces of aircraft can result from the lack of correct information about cleaning materials and equipment and their use. Shipboard procedures are not necessarily the same as procedures ashore, but the same materials are available to produce comparable results. A problem you may face when fighting corrosion is knowing what materials to use, where to find them, and their limitations. You should use only those materials that have military specifications. Corrosion control information can be found in many directives Figure 4-2.—Effects of area relationships in dissimilar metal contacts. 4-3

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and instructions. This information is constantly revised to give you up-to-date knowledge and procedures. You can find the following sources of information on corrosion in your unit’s technical library or corrosion control work center. Aircraft Weapons System Cleaning and Corrosion Control for Organizational and Intermediate Maintenance Levels, NAVAIR 01-1 A-509 Avionics Cleaning and Corrosion Prevention/ Control, NAVAIR l6-l-540 Preservation of Naval Aircraft, NAVAIR 15-01-500 Chart-Corrosion Preventive Compounds used by Naval Air Systems Command, NAVAIR 01-l A-518 General use of Cements, Sealants, and Coatings, NAVAIR 01-1A-507 Ground Support Equipment Cleaning And Corrosion Control, NAVAIR 17-1-125 Corrosion Control, Cleaning, Painting, and Decontamination (One volume of the maintenance instruction manuals (MIMs) for all late model aircraft is devoted to these subjects.) Q4. Q5. Q6. Q7. Q8. Q9. Q10. Q11. Q12. Periodic Maintenance Requirements Cards The decay of metals as they combine with oxygen is known as what type of corrosion? What does an intact coat of paint provide to naval aircraft? In an electrochemical attack, electron flow is established in which direction? How will heat, humidity, and moisture affect the electrochemical reactions that cause metal to corrode? Why are thick structural sections most susceptible to corrosive attack? In relation to corrosion, what affect does moisture have on avionics equipment? Which NAVAIR publication is entitled Aircraft Weapons Systems Cleaning and Corrosion Control? NAVAIR 16-1-540 provides what information? Information on the preservation of Naval aircraft and aircraft engines can be found in what publication? Q13. What information can you find in NAVAIR 01-IA-507? PREVENTIVE MAINTENANCE LEARNING OBJECTIVE: Define the purpose of a preventive maintenance program. “An ounce of prevention is worth a pound of cure.” Where corrosion prevention on naval aircraft is concerned, this is an understatement. Compared to the cost of naval aircraft, the cost of corrosion prevention is small. Preventive maintenance is a powerful tool that can control even the most difficult corrosion problem. Most operating activities increase their corrosion prevention programs to meet severe conditions aboard ship. Then, these programs are decreased in scope when the aircraft is returned to the relatively mild conditions ashore. When corrosion preventive maintenance is neglected because of tactical operating requirements, a period of intensive care should follow to bring the aircraft back up to standard. The two most important factors in preventing corrosion, and the only factors that can be controlled by field personnel, are the removal of the electrolyte and the application of protective coatings. Since the extent of corrosion depends on the length of time electrolytes are in contact with metals, corrosion can be minimized by frequent washing. Prevention also involves the correct and timely use of covers and shrouds, periodic lubrication, and the application of preservatives. Years of experience have proven the need for such measures to keep the aircraft airworthy. When corrosion preventive maintenance is neglected, an aircraft soon becomes unsafe to fly. Squadrons with the best corrosion preventive programs tend to have the best safety records, maximum use of the aircraft, and the lowest operating costs. SUPPORT EQUIPMENT PREVENTIVE MAINTENANCE SCHEDULE The Naval Aviation Maintenance Program (NAMP), OPNAVINST 4790.2, requires SE shops to establish a maintenance schedule for each item of equipment. The SE Custody and Maintenance History Record, OPNAV 4790/51, is used to schedule and record all corrosion maintenance actions. 4-4

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SURFACE MAINTENANCE Surface maintenance includes regular cleaning of the aircraft as well as touch-up of protective paint coatings. Since paint touch-up is done after removal of corrosion, it is discussed later in this chapter. Touch-up of new damage to paint finishes prevents corrosion from starting. Aircraft must be washed and cleaned at least every 14 days, unless otherwise directed by NAVAIR. Aircraft must be kept in a clean condition, and repeated cleaning should be done as often as necessary. More frequent cleaning may be needed when the following conditions exist: An excessive amount of soil or exhaust gases accumulation within impingement areas Exposure to salt spray, salt water, or other corrosive materials Evidence of paint surface decay, such as softening, flaking, or peeling The presence of fluid leakage (excessive oil, coolant, hydraulic fluid, etc.) Immediate cleaning of affected areas is always mandatory if: Aircraft is exposed to corrosive fire- extinguishing materials Spilled electrolyte and corrosive deposits are found around battery terminals and battery area The aircraft has been exposed to significant amounts of salt water Salt deposits, relief tube waste, or other contaminants are apparent Fungus growth is apparent Chemical, biological, or radiological contaminants are detected A daily cleaning or wipe-down is required on all exposed, unpainted surfaces, such as struts and actuating cylinder rods. Aircraft must be thoroughly cleaned before they are stored. They should also be thoroughly cleaned when they are depreserved. Unpainted aircraft are cleaned and polished at frequent intervals. Aboard ship, cleaning and removal of salt deposits are needed to prevent possible corrosion. Components that are critically loaded (designed with minimum safety margins to conserve size and weight) are cleaned as often as possible to minimize exposure to corrosive agents. These components include helicopter rotor parts and parts that are exposed to corrosive environments (such as engine exhaust gas, acid, or rocket blast). NOTE: Postcleaning lubrication and preservation of exposed components are necessary to displace any of the cleaning solution entrapped during the cleaning operation. Q14. Q15. Q16. Q17. Q18. What should happen to a good corrosion preventive program when carrier-based aircraft return to a shore activity after a deployment? Operating units that have the best safety records, maximum use of aircraft, and lowest operating costs will also have what program? At a minimum, how often must aircraft be cleaned? List the conditions that require the affected areas of an aircraft to be cleaned immediately. What must be done on a daily basis with unpainted aircraft surfaces and actuating rods? AVIONICS MAINTENANCE A successful avionics cleaning and corrosion prevention and control program depends upon a successful preventive maintenance program. The nature of corrosion requires that everyone involved in the repair and operation of electrical, electromechanical, and electronic systems be concerned with the corrosion control of avionic equipment. You should recognize the difference between the prevention of corrosion and the repair of damage caused by corrosion. Preventive maintenance programs at organizational- and intermediate-level maintenance activities accomplish the following: Reduce the maintenance time spent repairing corrosion damage Ensure the military avionics community is aware of the extent of the corrosion problem Improve avionics system reliability, durability, and service life Report any and every deficiency with material or process involving corrosion control CLEANING MATERIALS LEARNING OBJECTIVE: Identify the hazards of handling and storing aircraft cleaning materials. 4-5

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When cleaning or performing corrosion control on aircraft and nonavionics aircraft components, you should use the materials listed in Aircraft Cleaning and Corrosion Control for Organizational and Intermediate Maintenance Levels, NAVAIR 01-1A-509. You may use materials that do not conflict with the 509, as listed in the MIM and maintenance requirements cards (MRCs) that apply. For avionics and electrical systems, you should refer to the Avionic Cleaning and Corrosion Prevention/Control, NAVAIR 16-l-540. Cleaning agents commonly used by O- and I-level maintenance activities are described in the following text Figure 4-3.—DoD Hazardous Chemical Warning Label. CAUTION You must read the Material Safety Data Sheet (MSDS) before you use any hazardous mate- rial. Hazardous Materials Hazardous material is any material presenting hazards to personnel, property? or the environment by handling, storing, and using such materials. Hazardous materials can be used safely if you take extra precautions when handling and storing these materials. Hazardous material, such as chemicals, require a hazardous chemical or material identification label. Figure 4-3 shows a DoD Hazardous Chemical Warning Label. DoD personnel must use this label on DoD manufactured hazardous materials, repackaged containers, tanks of hazardous chemicals, and unlabeled materials already in the DoD system. Manufacturers use various symbols and DOT shipping labels with the required Occupational Health and Safety Administration (OSHA) labeling. Used alone, these DOT symbols or labels do not meet the OSHA labeling requirements. Navy personnel should not place any labels on containers that already have proper labels. If you buy or receive a hazardous material with the minimum required labeling, do not add any additional labeling. If you have an unlabeled container or one with a damaged label, you can print a label from the HMIS CD-ROM or use DD Form 2522. Flammable and Combustible Liquids Combustible liquids are any liquids that have a flash point at or above 100°F, but below 200°F. Flammable liquids are any liquids that have a flash point below 100°F. Fire is a very serious hazard. An equal hazard to personnel is breathing poisonous (toxic) fumes in unventilated spaces. NOTE: Flash point is defined as the minimum temperature at which a liquid gives off an ignitable vapor within a test vessel. Solvents Solvents are liquids that dissolve other substances. They are used in many products, such as paints, degreasing fluids, and aircraft cleaning compounds (an organic solvent). Aside from posing a fire hazard, inhaling the vapors can seriously affect the brain and 4-6

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the central nervous system. Therefore, you should use solvents only in well-ventilated spaces. You should wear gloves, an apron, and a face shield to protect your skin and eyes. You should also don an approved respirator to prevent breathing of the toxic vapors. Without protection, skin lesions, much like acne, may develop. If you do not use rubber gloves, your hands will lose their fatty protection and the skin will dry, crack, and become infected. Some solvents are chlorinated. When solvents contain more than 24 percent by volume of chlorinated materials, they must be kept in specially marked containers. You must ensure the equipment in which the solvent is used is designed and operated to prevent escape of the solvent. All personnel who work near chlorinated solvents should be careful to avoid breathing the vapors. While the vapors from some solvents are more toxic than others, prolonged breathing of any fumes presents a serious health hazard. Keep all containers holding paints, lacquers, removers, thinners, cleaners, or any volatile or flammable liquids tightly closed when not in use. Store all flammable and volatile liquids in a separate building or a flammable liquids storeroom. The approved flammable storage locker should be well ventilated. It should be located where its contents will not be exposed to excessive heat, sparks, flame, or direct rays of the sun. Storage areas must also have a fixed CO 2 or Halon extinguishing system. All electrical fixtures, outlets, and other wiring must be of the explosionproof class. Place wiping rags and other flammable waste material in tightly closed containers. You must empty these containers at the end of the work shift. You should keep in mind that the temperature inside the paint locker could become very high, especially during the summer months. As the temperature increases, liquids expand. Maintenance personnel have received serious chemical bums on the face, hands, and arms from opening a hot can of solvent. This hazard increases many times when personnel work with the more volatile liquids, such as paint strippers. Before opening a container of solvent that has been stored in a high-temperature area, you should cool it down. You can do this by using a stream of water. Use common sense around flammable and volatile liquids. When storing containers, you must handle them carefully to avoid breakage and spillage. If you stack the containers, the lower containers may be overloaded, causing leaks to develop along seams. This results in a loss of material. To prevent an accumulation of water and debris in their upper ends, store the containers on their sides or cover them with a tarpaulin. Before you store containers, you should inspect them for leaks and ensure complete closure of all plugs, caps, and covers. Inspect stored containers frequently for leakage, rust, or any other condition that may cause a problem. Correct deficiencies immediately. When storing materials outdoors, you should protect the containers from the weather with tarpaulins or sheds. This reduces the likelihood of water contamination. When you use tarpaulins, lash them in place securely and position them so that air is free to circulate around the containers. Another hazard associated with solvents (and to a certain extent with all cleaning materials) is their effect on the material being cleaned. Some solvents, such as methyl ethyl ketone and toluene, will damage rubber, synthetic rubber, and asphalt coverings. You should always consider this damaging effect when selecting cleaning materials. Most cleaning materials may do a good job in removing dirt, grease, oil, and exhaust gas deposits. However, they may also soften and ruin an otherwise good paint coating. For specific information on solvents, you should check NAVAIR 01-l A-509. Some solvents, consumable materials and their characteristics are described in the following text. Solvent, Dry-cleaning. This material is a petroleum distillate commonly used in aircraft cleaning. It is a general all-purpose cleaner available in three types and is used for metals, painted surfaces, and fabrics. It is applied by spraying, brushing, dipping, or wiping. Aliphatic Naphtha. Aliphatic naphtha is an aliphatic hydrocarbon product used as an alternate compound for cleaning acrylics. You may also use it for general cleaning purposes when you want fast evaporation and no film residue. Apply by dipping and wiping. DO NOT rub saturated surfaces vigorously. DO NOT use aliphatic naphtha with a synthetic wiping cloth, because it is a highly volatile and flammable solvent. Because it has a flash point below 80°F, use only in well-ventilated areas. Safety Solvent. Methyl chloroform is for use where a high flash point is required. Use it for general cleaning and grease removal from assembled and disassembled engine components in addition to spot 4-7

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cleaning. Do not use it on painted surfaces. Safety solvent is not suitable for oxygen systems. It can be used for other cleaning in ultrasonic cleaning devices. Apply it by wiping, scrubbing, or booth spraying. The term safety solvent is derived from its high flash point. Many later-issue maintenance manuals refer to safety solvent as 1,1,1-trichloroethane. Methyl Ethyl Ketone (MEK). Methyl ethyl ketone (MEK) is a cleaner for bare-metal surfaces and areas where MIL-S-8802 sealant is to be removed. Normally, you apply MEK over small areas with wiping cloths or soft bristle brushes. CAUTION Avoid prolonged breathing and skin con- tact of MEK. Use MEK only in well-venti- lated spaces. Use extreme care when working around transparent plastics because MEK will damage them upon contact. Trichloroethane. This is a nonflammable degreasing agent for cleaning oxygen systems equipment. It can be harmful to paint and plastic materials and since its vapors are heavier than air, it will displace oxygen in poorly ventilated areas. Ammonium Hydroxide. Normally, you use ammonium hydroxide in the lavatories of aircraft to neutralize urine and waste products. Use a sponge to apply it, and then flush the area with fresh water. Sodium Bicarbonate. Sodium bicarbonate also neutralizes urine deposits. You apply it with a sponge, and then flush the area with fresh water. Sodium bicarbonate is also a neutralizing agent for sulfuric acid battery electrolyte deposits. Sodium Phosphate. Sodium phosphate neutralizes electrolyte spills from nickel-cadmium batteries. Remove spilled electrolyte immediately by flushing with fresh water. Neutralize the area by sponging generously with sodium phosphate solution and then flush with fresh water. Dry with clean wiping cloths. Aqueous Film-forming Foam. Aqueous film-forming foam is commonly known as AFFF. Use it for removing fire-extinguishing agent MIL-F-24385 from aircraft surfaces. Complete details for the use of AFFF as a cleaning agent are in Aircraft Weapons System Cleaning and Corrosion Control. NAVAIR 01-1A-509. Aircraft Surface Cleaning Compound Maintenance personnel use water emulsion cleaners to clean aircraft. These cleaners disperse contaminates into tiny droplets that are held in suspension. The droplets of this cleaner are then flushed from the surface. MIL-C-43616 water emulsion compounds contain emulsifying agents, coupling agents, detergents, solvents, corrosion inhibitors, and water. Use these compounds on painted and unpainted surfaces in heavy-duty cleaning operations, when materials of lower detergency are not effective. Use these compounds in varying concentrations, depending upon the condition of the surface. Apply water emulsion cleaner by starting at the bottom of the area being cleaned. You may apply the mixed solution by spraying or brushing to avoid streaking. Loosen surface soils by mild brushing or mopping. Then, give the surface a thorough fresh water rinse by using an automatic shutoff-type water spray nozzle. This type of nozzle gives hand control from a light mist or fogging spray to a full spray with high-pressure water. Aircraft cleaning compound MIL-C-85570 is the primary cleaning compound used on naval aircraft. The five types of MIL-C-85570 are discussed in the following text. TYPE I is for cleaning painted and unpainted aircraft outdoors or where enough ventilation is available. It may be used to clean either high-gloss or tactical paint systems. TYPE II is for cleaning painted and unpainted aircraft indoors and in areas of limited ventilation. It is for cleaning either high-gloss or tactical paint systems. Type II is not as good as type I for these purposes. It may also be used outdoors. TYPE III is a mild abrasive cleaner. It is used undiluted for spot cleaning high-gloss paint systems, such as exhaust tracks, shoe scuff marks, and other areas where types I and II are not effective. TYPE IV is a spot cleaner for Tactical Paint Scheme (TPS). For spot cleaning embedded soils on TPS systems without changing the paint finish. TYPE V is for cleaning heavy soils, such as carbonized oil, aged preservatives, grease, and gun blast and exhaust deposits. This cleaner clings to 4-8

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vertical oily or greasy surfaces where water rinsing can be tolerated. AVIONIC CLEANING MATERIALS The materials discussed in this section are the ones used most often when avionics and electrical equipment are cleaned. For a complete list, description, and application of avionic cleaning materials. you should refer to NAVAIR 16-l-540. MIL-D-16791, type 1 detergent, is used to clean transparent plastics and glass. Also, it is used at I-level maintenance activities as a water-based solvent spray in cleaning booths and aqueous ultrasonic cleaners. For cleaning by hand, you should apply it to the area to be cleaned with a flannel cloth, let it dry, and then remove it with a flannel cloth. Trichlorotrifluoroethane is commonly known as Freon (MIL-C-81302 cleaning compound). It is a general cleaner for avionic and electrical systems. You can use MIL-C-81302 Freon as type I (ultraclean) or type II cleaner. The uses for these types of cleaners are discussed in the following text. TYPE I, MIL-C-81302, is used on precision equipment where an ultraclean solvent is required. It is used in clean room applications in intermediate-level maintenance activities. TYPE II: MIL-C-81302, is used on all internal areas of avionics equipment. Normally, type II should be filtered before it is used. It can be used to clean dirt and dust from areas before soldering. The application procedures and restrictions applying to MIL-C-81302, types I and II, are the same. They are as follows: Apply by wiping or scrubbing the affected area with an acid brush or toothbrush. Air dry or oven dry, as applicable. Do not use on acrylic plastics or acrylic conformal coatings. Do not use on unsealed aluminum electrolytic capacitors. Damage may result to end caps and cause leakage. Isopropyl alcohol (TT-I-735) is a general-purpose cleaner and solvent. Use it to remove salt residue and contaminants from internal avionics and electrical equipment. Use an acid brush or pipe cleaner to apply a solution of isopropyl alcohol and water. Then, wipe clean and air dry. NOTE: Isopropyl alcohol is highly flammable and requires the same handling and storage procedures as other solvents. MECHANICAL CLEANING MATERIALS Mechanical cleaning materials consist of items such as abrasive papers: polishing compounds, polishing cloths, steel wool, and wadding. These materials are available in the supply system. However, use them as outlined in the cleaning procedures section of NAVAIR 01-1A-509 and the specific MIM. These procedures prevent damage to finishes and surfaces. In cases of conflicting information, NAVAIR 01-1A-509 always takes precedence. Aluminum oxide abrasive cloth is available in several forms. It is safe to use on most surfaces because it does not contain sharp or needlelike abrasives. Avoid the use of silicon carbide papers as a substitute for aluminum oxide. The grain structure of silicon carbide is sharp. It is so hard that individual grains can penetrate steel surfaces. Impregnated cotton wadding is used to remove exhaust gas stains and to polish corroded aluminum surfaces. It is also used on other metal surfaces to produce a high reflection. Aluminum metal polish is used to produce a high-luster, long-lasting polish on unpainted aluminum-clad surfaces. It is not used on anodized surfaces because it will remove the oxide coat. Q19. Q20. Q21. Q22. Q23. Q24. Q25. What are the most serious hazards in handling, using, and storing aircraft cleaning materials? Why is there a requirement to use a respirator when working with solvents? What must be done specifically when storing solvents that contain more than 24% chlorinated materials? Where must flammable liquids be stored when not in use? By what means is dry-cleaning solvent applied? Safety solvent is currently referred to by what name? List the application procedures and restrictions that apply to ML-C-81302, types I and II. 4-9

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Q26. What material must be avoided as a substitute to aluminum oxide abrasive cloth and why? CLEANING EQUIPMENT LEARNING OBJECTIVE: Identify the cleaning compounds used in aircraft cleaning and the procedures for washing aircraft. Cleaning aircraft surfaces requires the correct cleaning materials and the use of properly maintained equipment. The choice of equipment depends upon several factors. Some of these are the amount of cleaning regularly performed, the type of aircraft, location of the activity, and the availability of air pressure, water, and electricity. Several types of specialized equipment are available for cleaning aircraft. These include pressure-type tank sprayers, a variety of spray guns and nozzles, high-pressure cleaning machines. and industrial-type vacuum cleaners. One piece of specialized equipment, the automatic water spray nozzle, is shown in figure 4-4. A device used for the fast, economical cleaning of aircraft is a swivel-type, conformable applicator cleaning kit (fig. 4-5). Its design allows you to clean aircraft exteriors faster than with cotton mops or bristle brushes. Its official designation is the Aircraft Cleaning Kit No. 251. The swivel and applicator head is attached to a standard brush handle. Because it conforms to the surface, the applicator allows easier application of a constant scrubbing pressure on curved skin panels. It does this by keeping the brushes in maximum contact with the surface. When you use these brushes, you must make sure they do not cause a FOD problem. CLASSIFICATION AND REMOVAL OF SOILS Soils may be classified and removed as described below: Lightly soiled surfaces (dirt, dust, mud, salt, and soot). Use the proper mixture of MIL-C-85570 and fresh water. Moderately soiled surfaces (hydraulic oils, lubricating oils, and light preservatives). Use a proper mixture of MIL-C-85570 and fresh water. Heavily soiled surfaces (carbonized oils, aged preservatives, grease, gun blast deposits, and exhaust Figure 4-4.—Automatic water spray nozzle. 4-10

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Figure 4-5.—Aircraft washing applicator. trails). Pretreat with P-D-680, followed by cleaning with the proper mixture of MIL-C-85570 and fresh water or MIL-C-43616. Soiled surfaces on the tactical paint scheme (low visibility flat paint scheme). Use MIL-C-85570, types I, II, or IV for cleaning tactical paint systems according to mixture directions. CLEANING PREPARATION The first step in cleaning an aircraft is to select the proper cleaning agent for the method of cleaning you will use. Next, the aircraft must be prepared for cleaning. Ground the aircraft to the deck. Static electricity generated by the cleaning operation will be dissipated through the ground wire. If the aircraft surface is hot, cool it with fresh water before starting any cleaning operation. Many cleaning materials will clean faster at elevated temperatures. However, the risk of damage to paint, rubber, and plastic surfaces is increased. This damage is caused by the cleaners, which are concentrated by the solvent evaporating quicker at high temperatures. Secure openings, such as canopies, doors, and access panels. Some equipment and components, such as air-sensing probes (pitot tubes), can be damaged by moisture and cleaning agents. To prevent the entrance of moisture, cover these and similar openings with either the proper aircraft cover or with masking tape, as specified in NAVAIR 01-1A-509, Appendix A. CLEANING METHODS There are several different methods for cleaning naval aircraft. These methods vary, depending upon the availability of fresh water. Water-Detergent Cleaning The water-detergent cleaning method is the preferred method for cleaning naval aircraft. Use this method when enough fresh water is available for rinsing. After preparation, wet down the aircraft surface to be cleaned with fresh water. Then, apply a concentrated solution of cleaning compound and water to heavily soiled areas. Scrub these areas and allow the concentrated solution to remain on the surface. Limit the size of the area you are cleaning to an area that can be cleaned while it is still wet. Next, apply a diluted solution of cleaning compound and water. The solution should be in a ratio suitable for the type of soil present in accordance with NAVAIR 01-1A-509. Apply this solution to the entire surface to be cleaned (upward and outward), including those areas previously covered with concentrated solution. The proper washing procedure is shown and described in figure 4-6. Scrub the surfaces thoroughly, and allow the solution to remain on the surface for 5 to 10 minutes before rinsing. Rinse the lower surfaces and work upward. Then rinse from the top down, starting with the vertical stabilizer, upper fuselage, upper wing surfaces, and horizontal stabilizers. Rinse lower areas in the same order and manner as the upper surfaces. If a high-pressure stream of water is used for rinsing, hold the nozzle at an angle and at a reasonable distance from the surface being sprayed. If any areas are still not clean, repeat the operation in those areas only. Thorough rinsing minimizes streaking. 4-11

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Figure 4-6.—Aircraft washing procedures. 4-12

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Detergent Cleaning With Limited Water Use this method only when water is limited. Prepare the aircraft for cleaning. Then mix the proper amounts of aircraft cleaning compound and water in a bucket. Apply the cleaner with a scrub brush, sponge, rag, or cleaning and polishing pad. Apply to one small area at a time. Scrub the area. Then remove the cleaner and loosened soils with a cloth. For soils that are resistant to the limited water procedure, clean with dry cleaning solvent (P-D-680, Type II or III) then repeat with the cleaning compound and water mixture. Apply water displacing, ultrathin, film corrosion preventive compound MIL-C-81309, type II, and wipe with a clean, dry cloth. Waterless Wipedown Cleaning Use waterless wipedown procedures only when water is not available for rinsing or when cold weather prevents the use of water. Using a plastic spray bottle, apply MIL-C-85570, Type I or II (mixed IAW NAVAIR 01-1A-509). Alternatively, spray the cleaner from an aerosol can and wipe off contaminates from the surface. Spot Cleaning Spot clean light, oily, soiled surfaces by wiping with dry-cleaning solvent. Apply the solvent by using a saturated wiping cloth. Brush or wipe the surface as necessary; then wipe clean with a dry cloth. The solvent wipe may leave a light residue. Remove this residue with soap and water, followed by a fresh water rinse. NOTE: After cleaning an aircraft, relubricate it as specified by the MRCs. Ensure that all low-point drains are open, covers and shrouds are removed, and that aircraft preservatives are applied to clean, exposed, unpainted surfaces. Also make sure that the felt wiper washers on all hydraulic cylinders are moistened, and wipe down actuating cylinder rods with a clean rag saturated with hydraulic fluid. Remove and replace damaged or loosened sealant as specified by the applicable MIM. Q27. Why is the conformable applicator cleaning pad better than a mop or bristle brush when cleaning aircraft surfaces? Q28. Types I, II, and IV of what cleaning compound are to be used on tactical paint schemes? Q29. What is the first step in efficiently cleaning an aircraft? Q30. When cleaning an aircraft what are the two directions in which cleaning compound and rinsing are applied? Q31. What substance may be used to spot-clean lightly soiled areas? AVIONICS EQUIPMENT CLEANING Dust and contamination cause corrosion problems in avionics equipment. Cleaning prevents many of these problems. Therefore, cleaning is the first logical step after an inspection. Cleanliness is very important in maintaining the functional integrity and reliability of avionic systems. Dirt may be either conductive or insulating. As a conductor, it may provide an undesired electrical path. As an insulator, it may interfere with proper operation. Dust, fingerprints, surface oxides, contaminants, or other foreign material on a surface can undo all the good provided by protective coatings. A good maintenance practice is to use the mildest cleaning method that will properly decontaminate the equipment. It is also important to use the correct cleaning solutions and cleaning materials to avoid damage to avionics equipment. Some of the hazards associated with the cleaning of electronic and electrical equipment are as follows: Cleaning solvents or materials can be trapped in crevices or seams. This interferes with later applications of preservative coatings and causes corrosion as well. Vigorous or prolonged scrubbing of laminated circuit boards can damage the boards. Certain cleaning solvents soften conformal coatings, wire coverings, acrylic panels, and some circuit components. WARNING Dry-cleaning solvent should not be used in oxygen areas or around oxygen equipment. Dry- cleaning solvent is NOT oxygen compatible and will cause explosion and/or fire. 4-13

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When dust. contaminants, or corrosion are detected, action is required. If the corrosion is within repairable limits specified in the applicable MIM or local directive. initiate corrective action. Corrective action includes cleaning, corrosion removal, treatment. and preservation. The nature of some surfaces, such as chrome-, nickel-, gold-, and silver-plated contacts. limits the use of highly abrasive cleaning methods. You can remove tarnish and light corrosion from these surfaces by rubbing with one of the following materials: An eraser (conforming to specification ZZ-E-661) known as magic rub, ruby red, wood, or paper encased (pencil-type) or typewriter eraser A nonabrasive cleaning pad (MIL-C-83957) for laminated circuit boards. waveguides, relay contacts. etc. A brush (toothbrush H-T-560 or typewriter brush H-B-681) for general scrubbing of dirt, soil, and corrosive products on circuit components Remove light to heavy corrosion from surfaces, such as covers, connectors, receptacles, antenna mounts, equipment racks, and chassis, by hand rubbing and by using aluminum oxide abrasive cloth. You may use either MIL-A-9962, type I, grade A (very fine), grade B (fine), or aluminum oxide abrasive cloth P-C-451, 320 grit, to do this task. USE OF COVERS AND SHROUDS When an aircraft is delivered by the manufacturer, it has a complete set of tailored dust and protective covers. Figure 4-7 shows a typical set of covers. Install all covers so free drainage will occur. Do NOT create a bathtub that will trap-and hold water. In warm weather, shrouds and covers cause a greenhouse effect, and cause condensation of moisture. Therefore, loosen and remove shrouds and covers and ventilate the aircraft on warm sunny days. However, where protection from salt spray is required, leave the covers in place, and ventilate the aircraft in good weather Figure 4-7.—Dust and protective covers. 4-14

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only. Fresh water condensation does far less damage than entrapped salt spray. In emergencies where regular waterproof canvas covers are not available, use a polyethylene sheet, polyethylene-coated cloth, or metal foil barrier materials as covers and shrouds. Hold these covers in place with adhesive tape that is designed specifically for severe outdoor applications. GROUND HANDLING REQUIREMENTS The MIM for an aircraft usually describe brief and simple ground-handling procedures. When followed, these procedures reduce corrosive attack. These procedures keep water, salt, and dirt out of areas that are difficult to get at and easy to overlook. As you can see, they also save a tremendous amount of maintenance work later. Many practices, when followed, lessen paint damage and the loss of built-in protective systems during normal ground handling of the aircraft. Some of these practices are listed below. Use the tie-down points provided. Much damage is done to aircraft paint films by failure to use the tie-down points or by passing tie-down cables and lines over or around supporting structures so the paint finish is worn, chipped, or broken. Take time to wipe or brush sand or gravel from shoe soles before climbing on the aircraft. Painted aircraft surfaces will withstand a normal amount of foot traffic and abrasion by fuel hoses and air lines. However, shoe soles and fuel hoses pick up bits of sand, gravel, and metal chips. These become a coarse abrasive that scratches and scuffs the protective finish so it is completely ineffective under shipboard operating conditions. Do not place removed hardware on the deck. When you remove cowling and access plates during inspections and you cannot provide pads or cushions for them, secure them to prevent their movement. Avoid scratching the paint when you use hand tools to remove screws and quick-opening fasteners on aircraft exteriors. As little as 5 minutes of extra time spent carefully using tools might save hours of paint touch-up and corrosion removal. Q32. Why should dry-cleaning solvent not be used in oxygen areas or around oxygen equipment? Q33. In emergencies when regular waterproof canvas covers are not available, what materials can you use as covers and shrouds? Q34. The ground handling requirements for an aircraft can be found in what publication? RECOVERY AND RECLAMATION OF CRASH DAMAGED AIRCRAFT LEARNING OBJECTIVE: Identify publications used to describe emergency reclamation procedures. General procedures are required anytime an aircraft is exposed to gross amounts of saltwater or fire-extinguishing agents. Each activity that is assigned custody of aircraft has a recovery and reclamation team. The size and composition of the team depend upon the urgency of the situation. As a maintenance crew member, you may be called upon to assist with reclamation of an aircraft. Recovery and reclamation procedures are covered in detail in NAVAIR 01-1A-509. Methods for cleaning support equipment (SE) are different from those used to clean aircraft. Authorized SE cleaning materials and procedures are identified in Ground Support Equipment Cleaning and Corrosion Control, NAVAIR 17-1-125. Q35. What technical publication covers emergency reclamation procedures for naval aircraft? LEVELS OF AIRCRAFT PRESERVATION LEARNING OBJECTIVES: Describe the levels of aircraft and engine preservation. Identify the preservatives and sealants used in the preservation of aircraft and support equipment. The exposure of an aircraft to corrosion damage is greatest when the aircraft is dirty, inactive, or being shipped. Aircraft spend more time on the ground than in the air, even in an active squadron. Therefore, they must be effectively protected. The method of preservation is based on complexity of the aircraft. A variety of methods are used to preserve aircraft. Preservation applies to all types of naval aircraft. There are three different levels of preservation used on naval aircraft: 4-15

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Level Use I Short-term preservation of flyable and nonflyable aircraft for periods up to 60 days Preservation of aircraft for shipment and forII periods of 60 days to 1 year Preservation for long-term aircraft storageIII for periods of 1 to 8 years NOTE: Level I preservation will have special MRCs for each aircraft/engine. As a maintenance crew member, you will be involved with level I preservation. Anytime an aircraft is out of service or will remain idle for 14 or more days, maintenance will put the aircraft in level I preservation. You will use special MRCs to preserve, maintain preservation, and depreserve an aircraft. Protection against corrosive attack on aircraft is achieved by placing a barrier between the surface and any possible source of moisture. During overhaul or manufacture, protective barriers, such as electroplate, paint, or chemical surface treatment, are provided. Surfaces that cannot be so treated (in some instances, the treated surfaces themselves) are covered with special corrosion-preventive compounds. These compounds are effective only if no moisture, dirt, or active corrosion is present on the treated surface. Therefore, you must thoroughly clean and dry the aircraft before applying a preservative compound. Also, you must apply an unbroken film of preservative in as moisture-free an atmosphere as possible. Complete protection is not provided by compounds alone. Tapes, barrier paper, and sealing devices are used to seal off the many openings on aircraft. If these openings were to remain open during long-term storage, moisture and dirt would enter and accumulate. To provide additional protection against corrosion, a complete moisture barrier is sometimes used on aircraft. Unless the cavity is protected by a vapor corrosion inhibitor, use desiccants to dehydrate internal areas that have been sealed. When an area cannot be sealed adequately, provide ventilation and moisture drainage. When installed equipment in an aircraft is not being regularly used, its components must be preserved. For example, the guns of an aircraft must be cleaned after each firing. The type of oil or other protective treatment used depends upon the anticipated period of idleness for the guns. In the maintenance of aircraft surfaces under operating conditions, preservation adds to the protection already present. Also, protection coating and barrier materials provide temporary protection to damaged areas. A brief description of some of the more common materials used in aircraft preservation that are readily available in Navy stock is given in the following text. Corrosion-Preventive Compound, Solvent Cutback Corrosion-preventive compound, solvent cutback, comes in grades for specific applications. There are five grades of this compound, three of which are commonly used and do not displace water, grades 1, 2, and 4. All grades can be removed with dry-cleaning solvent. These materials are designed for cold application. 4-16 Grade 1 preservative forms a dark, hard-film, opaque cover. Its general use is limited because of the difficulty in removing aged coatings. Also, it hides what corrosion is present when it is applied over corroded areas. This material is used where maximum protection against salt spray is required. The military specification is MIL-C-16173, grade 1. Grade 2 is a thick soft, greaselike compound which is used primarily to protect metal surfaces against corrosion during rework or storage periods. The military specification is MIL-C-16173, grade 2. Grade 4 preservative forms a thin, semitransparent film through which identification dates can be read. It sets up dry enough to the touch, so preserved parts may be handled easily. This grade is effective in protecting wheel well areas and other exposed surfaces where film transparency is required and moderate protective characteristics can be tolerated. Its main disadvantage is that it is easily removed by water spray and requires replacement at l-month intervals under severe exposure conditions. The military specification is MIL-C-16173, grade 4. Coating Compounds Activities based outside the Continental United States sometimes receive aircraft via ocean surface shipment. This is especially true of helicopter and limited-range fighter aircraft. These aircraft are

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protected during shipment with a sprayable, strippable coating system that conforms to MIL-C-6799, type II. Normally, type II coatings are safe on metal, plastic, or painted surfaces. Also, they are useful for protecting clear acrylic surfaces, such as canopies, against abrasion during maintenance or extended periods of downtime. The type II system consists of a black base coat and a white topcoat that provides heat reflection during outside exposure. Nylon ripcords with finger-size loops are placed about the aircraft before the aircraft is sprayed with this coating. This allows manual stripping of coatings. When properly applied, the coatings can be removed easily. If coatings are sprayed too thin for easy removal, they can be recoated and allowed to dry. The top layer will bond to previous layers, and all layers may be manually stripped in one operation. Corrosion-Preventive Petroleum (MIL-C-11796) MIL-C-11796 is designed for hot application. It is available in two classes, class 1 (hard film) and class 3 (soft film). Both classes consist of corrosion inhibitors in petroleum. They are removed with Stoddard solvent or mineral spirits. Where a hard film is not necessary, you should use class 3. Class 3 is easier to apply and remove, yet it gives the same degree of protection as class 1. Class 1 is for long-time, indoor protection of highly finished metal surfaces and aircraft control cables. Class 3 provides protection for metal surfaces, such as antifriction bearings, shock-strut pistons, and other bright metal surfaces. Class 1 must be heated to 170°F to 200°F before it is applied by brush or dip. For brushing, class 3 material must be between 60°F and 120°F, and for dipping, between 150°F and 180°F. Oil, Preservative, Hydraulic Equipment (MIL-H-46170) Use hydraulic fluid MIL-H-46170 as a preservative fluid to store hydraulic systems and components. It is also used as a testing medium in stationary test stands within a temperature range of -40°F to +275°F. Hydraulic fluid MIL-H-46170 is NOT to be used in portable test stands that are connected to the aircraft. This hydraulic fluid is a fire-resistant, synthetic, hydrocarbon, hydraulic fluid similar to MIL-H-83282. MIL-H-46170 is used as a preservative fluid in systems operating on MIL-H-83282. Lubrication Oil, General-Purpose, Preservative There are several types of lubricating oils, some of which contain preservatives. Each oil is identified by a specification number. Use the correct oil for each situation. The specification number for the oil described in this section is VV-L-800. VV-L-800 oil is used to lubricate and protect piano-wire hinges and other critical surfaces. It is also used when a water-displacing, low-temperature, lubricating oil is required. You may apply VV-L-800 as received by brush, spray, or dip. It is readily removed with dry-cleaning solvent or mineral spirits. Corrosion-Preventive Compound (MIL-C-81309) MIL-C-81309 corrosion-preventive compound is a water-displacing compound and lubricant that must be reapplied frequently. On exposed surfaces, protection lasts about 7 days at best. On internal areas, protection lasts about 30 days. MIL-C-81309 is available in two types—type II and type III. Type II is used for external areas. It forms an effective barrier against moisture when used on B-nuts, linkages, bolts, nuts, ejection seat mechanisms, and canopy locks. When you lubricate an area where there are no pressure lubricating fittings (zerk fittings), such as the piano hinges on access doors and control surfaces, spray with type II preservative compound to clean the area before you apply VV-L-800 preservative oil to remove moisture and contaminants. Type III corrosion-preventive compound is for avionics and electrical equipment usage. It is not for use on exterior areas that will be exposed to the environment. Type III is used primarily on electrical connectors (cannon plugs) and microswitches to remove moisture and contaminants and to prevent corrosion. Packaging and Barrier Materials A minimum of packaging is necessary at the operating activity level. However, critical aircraft and engine areas require shrouding against contamination during maintenance and repair. The fuselage must be sealed when cleaning and stripping materials are used 4-17

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on the aircraft. There are several barrier materials available in the Navy stock for sealing and shrouding large aircraft openings. The stock numbers for these materials can be found in NAVAIR 01-1A-509. Water-vaporproof Barrier Material. This material is a laminated metal foil barrier that has good water-vapor resistance. It is used for closing intake openings, protecting acrylics during cleaning, and for the packaging of removed components and accessories that are returned for overhaul. It is heat sealable with a soldering or clothes iron. Polyethylene Plastic Film. This barrier material is used for the same purpose as the metal foil barrier material, but it is less expensive. However, it is not puncture resistant. This plastic film is heat sealable only with special equipment. Polyethylene Coating Cloth. This cloth is used in support equipment covers. Its use is preferred over plastic film material for general shrouding because of its greater tear and puncture resistance. Tape, Federal Specification PPPT-60, Class 1. This pressure-sensitive tape is used to close small aircraft openings and for direct contact use on noncritical metallic surfaces. It has moderate water-vapor resistance that is adequate for maintenance use. Pressure-sensitive Adhesive Tape. This tape was developed specifically for exterior preservation and sealing. It can be applied at temperatures as low as 0°F. It should perform satisfactorily over a temperature range of -65°F to +140°F. It is an excellent general-purpose tape for exterior preservation and sealing operations. Q36. Q37. Q38. Q39. Q40. Q41. State the levels and terms of preservation used for naval aircraft. What level of preservation is required if an aircraft is scheduled to remain idle for more than 14 days but less than 28 days? MIL-C-16173, corrosion preventive compound, is available in three grades. Which grade(s) is/are easily removed with dry-cleaning solvent? Corrosion-preventive petroleum, class 3, provides protection for what type of surfaces? When is general-purpose lubrication oil VV-L-800 used? What type of corrosion-preventive compound MIL-C-81309 is used on avionics and electrical equipment? ENGINE PRESERVATION NAVAIR 15-01-500, Preservation of Naval Aircraft, addresses specific requirements for the cleaning, inspection, protection, maintenance, and depreservation of auxiliary power units, gas turbine engines, and reciprocating engines. This section only highlights some important factors in engine preservation. Refer to the Preservation Manual for specific details. Level I preservation of engines requires the fuel system to remain at least 95% full of fuel for a period not to exceed 60 days. Any fuel system that has been drained of fuel for more than 3 days or is expected to remain inactive for more than 60 days is to be preserved with MIL-L-6081 Grade 1010. and be dehumidified. Level II and III preservation requirements are also outlined in the Preservation Manual. All requirements are listed by type engine and level of preservation desired. NOTE: In any case of preservation, ensure all logbook entries and preservation tag requirements have been met. SUPPORT EQUIPMENT PRESERVATION WARNING Do NOT use oil-based preservatives around oxygen fittings or oxygen regulators since fire or explosion may result. The preservation of clean, corrosion-free surfaces is the final step of the preventive maintenance process of SE. The act of preservation helps to protect nonmoving parts by filling air spaces, displacing water, and providing a barrier to corrosion. Preservatives For SE Preservatives are used after SE cleaning before ocean assignment when an extended period of SE storage is anticipated. Preservatives are also used wherever paint films require additional preservative (for example, in metal joints, tightly fitting surfaces, and on sump areas). The technical corrosion manual to be used for support equipment is Ground Support Equipment Cleaning And Corrosion Control, 4-18

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NAVAIR l7-1-125. This publication takes precedence over any and all MIMs and service instruction manuals (SIMs) at both O- and I-level maintenance activities. This manual spells out specifically which materials and procedures you are to use to clean up corrosion and restore the protective surface. You still follow the maintenance and service manuals in conjunction with matters not pertaining to corrosion control. The four primary preservative compounds recommended for use on SE are listed in table 4-1. Apply corrosion-preventive compound to all exposed SE hardware items (around light brackets, hand brakes, levers, dissimilar metal joints, and tightly fitting surfaces and so forth). Preserve areas and components according to the following general procedures: 1. After removing corrosion products, clean the surface and spray the area with water-displacing agent, MIL-C-81309, type II. 2. Apply an even, thin coating of corrosion- preventive compound, MIL-C-16173, grade 4, or MIL-C-85054 to all nonmoving, difficult-to-protect areas. Use only MIL-C-16173, grade 4, for fasteners. 3. Dip removable screws and fasteners in corrosion-preventive compound before installation. 4. Remove excess compound from the metal surface with solvent, P-D-680, and clean cloth, DDD-R-30. Sealants For SE Sealants are brush- or spatula-applied compounds for SE corrosion prevention. These compounds are used primarily to repair damaged door and cover weather seals, fill depressions resulting from corrosion repair, protect heavy bolts and fasteners, and seal corrosion-prone crevices and lap seals. Two sealants recommended for SE are Silicone Sealant MIL-A-46146, type I, and Polysulfide Sealant MIL-S-81733 (inhibited) or MIL-S-8802 (uninhibited). When properly applied, the sealant forms as a barrier to the penetration of moisture. Prepare metal surfaces carefully before the application of a sealant. Do NOT apply sealant over visible moisture. Ensure that the sealant forms a continuous film at all seams, especially where dissimilar metals are in contact. When applying sealants on SE, you should use the following steps: 1. Mix the sealant according to the manufacturer’s direction. 2. Dip bolts or fasteners into the sealant so that the threads and shanks are completely covered. Immediately install the bolt in tapped holes. 3. Brush or swab sealant on mating surfaces that form a crevice when assembling parts. Immediately assemble these parts. 4. Pour, spoon, or trowel sealant into crevices that cannot be disassembled for treatment. Q42. What level of engine preservation requires the fuel system to remain at least 95 percent full of fuel for a period not to exceed 60 days? Q43. What technical corrosion manual should you use for support equipment? Q44. What are the two sealants recommended for use on support equipment? Table 4-1.—SE Preservatives Preservative compound Use Corrosion-Preventive Compound, Water-displacing, For all exposed metal and hardware not Ultrathin Film, MIL-C-81309, type II, class 2 exposed to the elements Corrosion-Preventive Compound, Water- Displacing, Clear, A general exterior surface preservative to MIL-C-85054, type I (AMLGUARD) produce an even, thin, nontacky, and clear film Corrosion-Preventive Compound, Solvent Cutback, Cold A general external preservative, which Application, MIL-C-16173, grade 4 produces a semitransparent film Corrosion-Preventive Compound, Ultrathin Film, Avionics A general preservative for internal areas of Grade, MIL-C-81309, type III electric components 4-19

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CORROSION DETECTION LEARNING OBJECTIVE: Identify the types, forms, and characteristics of corrosion. Timely detection of corrosion is essential to any corrosion control program. Of course, corrosion can be detected after a part fails (if the equipment can be recovered). However, then it is too late to do anything about it other than to intensify inspections of other similar aircraft and SE. Inspection for corrosion should be a part of all routine inspections. On every aircraft and piece of SE, there are certain areas that are more corrosion prone than others. You should check these areas carefully. For the corrosion inspection to be thorough, you must know the types of corrosion likely to be found and the symptoms or appearance of each type of corrosion. Sometimes corrosion is hidden, and special detection methods are used to find it. Various aspects of corrosion detection are discussed in the following text. FORMS OF CORROSION Corrosion may occur in several forms, depending upon the specific function, size, shape and type of metal involved. Atmospheric conditions and the presence of corrosion-producing agents are also factors in the development of corrosion. The types of corrosion described in this section are the more common forms found on aircraft structures and SE. This text uses the most commonly accepted terms that describe the various types of corrosion. Uniform (Direct) Surface Attack The surface effect produced by the direct reaction of a metal surface with oxygen in the air is a uniform etching of the metal. The rusting of iron and steel, the tarnishing of silver, and the general dulling of aluminum surfaces are common examples of surface attack. On aluminum surfaces, if the surface attack is allowed to continue, the surface will become rough and eventually frosted in appearance. Figure 4-8 shows direct surface corrosion on an A-6 landing gear linkage system. Pitting Corrosion The most common effect of corrosion on aluminum and magnesium alloys is called “pitting.” The primary cause of pitting is the variation in structure or quality between areas on the metal surface in contact with a corrosive environment. Pitting corrosion is first noticeable as a white or gray powdery deposit, similar to dust, which blotches the surface. When the superficial deposit is cleaned away, tiny pits or holes can be seen in the surface. They may appear as shallow indentations or deep cavities of small diameter. Pitting may occur in any metal, but it is particularly characteristic of aluminum and magnesium. Figure 4-9 is an illustration of pitting corrosion. Crevice Attack or Concentration Cell Concentration cell corrosion is actually a form of pitting corrosion. Concentration cell corrosion is caused by the difference in concentration of the electrolyte or the active metal at the anode and cathode. When there are concentration differences at two different points in an entrapped pool of water or cleaning solution , anodic and cathodic areas may result. This results in the anodic area being attacked. Figure 4-10 shows the theory of concentration cell corrosion. Areas where there are crevices, scale, surface deposits, and stagnant water traps are prone to this type of attack. Concentration cell corrosion is controlled and prevented by avoiding the creation of crevices during repair work. It is also controlled with sealants and caulking compounds that eliminate voids that trap water. Intergranular Attack, Including Exfoliation All metals consist of many tiny building blocks called “crystals” (sometimes called grains). The boundaries between these crystals are commonly called “grain boundaries.” Intergranular corrosion is an attack on the grain boundaries of some alloys under specific conditions. During heat treatment, these alloys are heated to a temperature that dissolves the alloying elements. As the metal cools, these elements combine to form compounds. If the cooling rate is slow, they form at the grain boundaries. These compounds differ electrochemically from the material adjacent to the grain boundaries, and they can be either anodic or cathodic to the adjoining areas, depending upon their composition. The presence of an electrolyte results in attack of the anodic area. This attack can be rapid and exist without visible evidence. As the intergranular corrosion progresses to the more advanced stages, it lifts the surface grain of the 4-20

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205.153Figure 4-8.—Surface corrosion on hydraulic linkage. metal. This is caused by the force of expanding corrosion products at the grain boundaries just below the surface. This advanced attack is called exfoliation (fig. 4-11). At this point, it can be seen by maintenance personnel. Correction of such serious corrosion is vital to aircraft safety. The insidious (sneaky) nature of such an attack can seriously weaken structural members before the volume of corrosion products accumulate on the surface and the damage becomes apparent. Metal that has been properly heat-treated is not readily prone to intergranular attack. However, localized overheating, such as could occur from welding and fire damage, can make metal prone to attack. If the intergranular attack has not penetrated so far as to impair structural strength, correction as outlined in the applicable structural repair manual (SRM) can restore an aircraft to flight status. Dissimilar Metal Corrosion The terms galvanic or dissimilar metal corrosion are applied when accelerated corrosion of metal is caused by dissimilar metals being in contact in a corrosive medium, such as salt spray or water. Dissimilar metal corrosion is usually the result of a 4-21

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205.154 Figure 4-9.—Pitting of an aluminum wing assembly. Figure 4-10.—Concentration cell corrosion. faulty design or improper maintenance practices. You To keep these metals from coming in direct can usually recognize it by the presence of a buildup contact with each other, aircraft and support of corrosion at the joint between the metals. For equipment manufacturers use a variety of separating example, aluminum and steel materials riveted materials. Such materials include plastic tape, sealant, together in an aircraft wing form a galvanic couple if primer, washers. and lubricants. These materials keep moisture or contamination is present. When aluminum corrosion to a minimum. These separating materials pieces are attached with steel bolts or screws, galvanic must remain intact and be replaced, restored. or corrosion can occur around the fasteners (fig. 4-12). repaired as needed. 4-22

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Figure 4-11.—Intergranular corrosion. Figure 4-12.—Galvanic corrosion. 4-23

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Some metals are more active than others. The degree of attack depends upon the relative activity of the two surfaces in contact. The more active or easily oxidized surface becomes the anode and corrodes. In plated metal, the possibility of dissimilar metal corrosion becomes a factor only if there are defects in the plating. Moisture penetrates and galvanic cells form because of these defects. Stress Corrosion Stress corrosion is caused by the combined effects of tensile stress and corrosion. Stress may be internal or applied. Internal stresses are produced by nonuniform deformation during cold working, by unequal cooling from high temperatures during heat treatment, and by internal structural rearrangement involving volume changes. Stresses set up when a piece is formed. Stress induced by press-and-shrink fits and those in rivets and bolts are examples of internal stresses. Concealed stress is more important than design stress because it is difficult to recognize before it exceeds the design safety factor. The magnitude of the stress varies from point to point 4-24 Figure 4-13.—Stress corrosion cracking. within the metal. Stresses that approach the yield strength of the metal promote stress cracking (visible at this point), but failure can occur at lower stresses (fig. 4-13). Most often, stress cracks are not visible to the naked eye and are discovered in the nondestructive inspection (NDI) process. Fatigue Corrosion Fatigue corrosion is a special kind of stress corrosion. It is caused by the combined effect of corrosion and stress applied in cycles to a component. An example of cyclic stress is the alternating loads to which the reciprocating rod on the piston of a hydraulic, double-acting, actuating cylinder is subjected. During the extension stroke, a compression load is applied. During the retracting or pulling stroke, a tensile or stretching load is applied. Fracture of a metal part due to fatigue corrosion commonly occurs at a stress far below the fatigue limit in a laboratory environment, even though the amount of corrosion is unbelievably small. This is why protection of parts subject to alternating stress is particularly important in any environment. Figure 4-14 shows an oil cooler blower that disintegrated because of fatigue corrosion of a blade (shown by arrow). Fretting Corrosion Fretting corrosion is a limited but highly damaging type of corrosion. It is caused by a slight vibration, friction, or slippage between two contacting surfaces that are under stress and heavily loaded. It is usually associated with machined parts. Examples of these parts are the area of contact of bearing surfaces, two mating surfaces, and bolted or riveted assemblies. At least one of the surfaces must be metal. In fretting corrosion, the slipping movement on the contacting surface destroys the protective films that are present on the metallic surface. This action removes fine particles of the basic metal. The particles oxidize and form abrasive materials, which further agitate within a confined area to produce deep pits. Such pits are usually located in an area that increases the fatigue failure potential of the metal. Early signs of fretting corrosion are surface discoloration and the presence of corrosion products in lubrication. Lubrication and securing the parts so that they are rigid are effective measures to prevent this type of corrosion. 205.157

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205.158 Figure 4-14.—Oil cooler blower disintegration. Filiform Corrosion Filiform corrosion (fig. 4-15) consists of threadlike filaments of corrosion known as underfilm. Metals coated with organic substances, such as paint films, may undergo this type of corrosion. Filiform corrosion occurs independently of light, metallurgical factors, and microorganisms present. It takes place when the relative humidity of the air is 78 to 90 percent and when the surface is slightly acidic. Although the threadlike filaments are visible only under clear lacquers or varnishes, they also occur under opaque paint film. Filiform corrosion can attack steel, aluminum, and magnesium. Microbiological Corrosion Microorganisms contained in seawater can be introduced into fuel systems by contaminated fuel. These fungus growths attack the sealing material used on integral fuel tanks. They can cause corrosion of aluminum, probably by aiding in the formation of concentration cells. Residues from biological growth tend to clog fuel filters and coat fuel quantity probes. Fuel quantity probes thus coated give erroneous readings. Also, moisture aides in the growth of fungi and microorganisms in avionic equipment. Q45. The tarnishing of silver is a common example of what type of corrosion? Q46. Pitting is the most common effect of corrosion on what alloys? Q47. Pitting corrosion is first noticeable as what color deposit on a metal surface? Q48. How can concentration cell corrosion be controlled or even prevented? Q49. Define intergranular corrosion. 4-25

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205.159 Figure 4-15.—Filiform corrosion found under paint coating. Q50. What is usually the cause of dissimilar metal corrosion? Q51. What are some examples of internal stress corrosion? Q52. What causes fatigue corrosion? Q53. What is the cause of fretting corrosion? Q54. Filiform corrosion occurs on what types of metals? LOCATION OF CORROSION- PRONE AREAS LEARNING OBJECTIVE: Describe the areas on an aircraft prone to corrosion. This section discusses corrosion-prone areas common to all aircraft. For specific aircraft, you should refer to the periodic maintenance information cards (PMICs) to locate corrosion-prone areas for that aircraft. Figure 4-16 is an example of possible trouble spots on jet engine aircraft. Lavatories and galleys are likely trouble spots if they are not kept clean. These areas include the deck behind lavatories, sinks, and ranges where spilled food and waste products may accumulate. Even when contaminants are noncorrosive: they may attract and hold moisture. This, in turn, causes corrosive attack. Maintenance personnel should pay attention to bilge areas located under galleys and lavatories and to personnel relief and waste disposal vents or openings on the aircraft exteriors. Human waste products can corrode common aircraft metals. Avionic Systems The control of corrosion in avionic systems is not unlike that in airframes. Procedures useful for airframes apply to avionics, with appropriate modifications. Avionics systems are more prone to corrosion than aircraft because avionics have the following characteristics: Less durable protection systems, Very small amounts of corrosion can make equipment inoperative. Dissimilar metals are often in electrical contact. Stray currents are present that can cause corrosion. 4-26

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1. Radome area 2. Rudder petal 3. Cockpit floor 4. Battery compartment 5. Piano hinges 6. Flight control cables 7. Exhaust areas 8. Missile rocket blast area 9. Flap carriage area 10. Magnesium wheels 11. Exposed rigid tubing 12. Main wheel well 13. Air inlet ducts and engine frontal areas 14. Nose wheel well Figure 4-16.—Typical corrosion-prone areas on jet engine aircraft. Active metals and dissimilar metals in contact are often unprotected. Closed boxes can produce condensation during normal temperature changes during flight. Avionic systems have many areas to trap moisture. Hidden corrosion is difficult to detect in many avionic systems. Many materials used in avionic systems are subject to attack by bacteria and fungi. Organic materials are often used that, when overheated or improperly or incompletely cured, can produce vapors. These vapors are corrosive to electronic components and damaging to coatings and insulators. The only requirements for a corrosion cell are a cathode, an anode, and an electrolyte. The size of a cell depends upon the size of its components. A cell can form where a resistor lead is soldered to a terminal, or where two sheets of metal join. It can also form around a rivet head and the adjacent metal. (See figure 4-17, views A and B.) Even two metallic crystals in the same alloy can form a cell. All that is needed is for crystals to be of different composition and in electrical contact with each other in the presence of an electrolyte (fig. 4-17, view C). Battery Compartments and Battery Vent Openings. Fumes from battery electrolyte are difficult to contain. They will spread throughout the battery compartment, vents, and even adjacent internal cavities. Battery electrolyte fumes cause rapid corrosive attack on unprotected surfaces. Maintenance personnel should check the external skin area around the vent openings regularly for this type of corrosion. Corrosion from this source is a serious problem 4-27

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228.53 Figure 4-17.—Electrochemical corrosion. whenever batteries are used. The battery compartment shown in figure 4-18 needs immediate attention. WARNING Before performing any cleaning, inspec- tion, or maintenance on electrical systems, maintenance personnel should make sure that all electrical power is secured from the air- craft. If the electrical power is NOT secured from the aircraft, it could result in serious injury to maintenance personnel. Multiple Electrical Connectors (Cannon Plugs). Connectors mounted in avionic and electrical systems are prone to the same corrosive environment as airframe structural components (fig. 4-19). Normally, connectors and mounting plates contain a gasket that acts as a watertight seal. When maintenance personnel dismantle (take apart) a connector for cleaning or repair, they should inspect the gasket. They should give special attention to connectors that use replaceable pins. These connectors use a self-sealing gasket water seal or dog bones (plastic inserts) that automatically seal the connectors against water intrusion. The repeated removal and replacement of the pins or forgetting the dog bones may cause the watertight seal to lose its effectiveness. In extreme cases where the connector cannot be replaced, potting compounds must be used to prevent water intrusion. You can find the stock numbers for dog bones in the applicable IPB. Coaxial Connectors. Look at figure 4-20. It shows corrosion on a coaxial connector. Coaxial connectors require special steps to avoid water intrusion. Usually, moisture, contaminants, and corrosion in fuel quantity, oil quantity, and similar capacitive-type indicating system connectors cause erroneous (wrong) quantity indications in the cockpit indicating systems. Antenna coaxial connectors have similar problems with moisture. Wire Harnesses and Cables. When corrosion is discovered at the pin-to-wire connection on electrical connectors, plugs, and receptacles, the wire harness 4-28

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205.160Figure 4-18.—Battery compartment. and cables should be inspected for corrosion attack and cracking of the wire insulation. Cable shielding is particularly prone to corrosion. Ram Air Turbine (Rat) Compartments. Maintenance personnel should inspect RAT compartments for moisture traps. They should inspect all mounting hardware, electrical connectors, terminal boards, junction boxes, and the RAT itself for signs of corrosion that may have been caused by moisture spray. Electrical Bonding and Grounding Straps. The bonding and grounding straps used on aircraft and electrical equipment are major sources of galvanic corrosion. Usually, this strap is made of a metal that is dissimilar to the areas to which it is attached. Thus, a galvanic couple is created. Unless maintenance personnel take proper preservation action, this couple, in the presence of moisture, corrodes at a rapid rate. 4-29

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205.161 Figure 4-19.—Corrosion on control box electrical connectors. 205.162 Figure 4-20.—Corrosion on coaxial connector. Light Assemblies. External formation lights, wing tip lights, rotating beacons, and lower fuselage anticollision lights are highly prone to corrosion. These lights are prone to corrosion because of poor seals, exposure to the elements in flight, or water intrusion during aircraft washdown. Usually, corrosion is heavy at the bases of the bulbs because of dissimilar metal contact between bulbs and sockets. Seals and preservation actions reduce the likelihood of corrosion in light assemblies. Q55. The corrosion-prone areas for each specific aircraft are derailed in what publication? Q56. What are the three requirements for a corrosion cell to form? Ejection Seats Aboard ship, salt spray enters most aircraft cockpit areas when the canopies are opened for respotting of aircraft maintenance or to accommodate the manning of ready alert aircraft. While the cockpit and ejection seats are not as corrosion prone as some other areas, they are still in a corrosive environment. Therefore, the cockpit and ejection seats require constant attention, along with other parts of the aircraft. Because of their construction and location, ejection seats are difficult to inspect and clean thoroughly while they are installed in the aircraft. Also, there is a lengthy period of time between aircraft inspections that require seat removal. Therefore, 4-30

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205.164 Figure 4-21.—Corrosion-prone point of air inlet duct. ejection seats could become severely corroded if not given adequate attention. The likelihood that slight corrosion could make an ejection seat inoperable must not be overlooked. The MRCs for these seats require that every portion of the seats be checked thoroughly for corrosion when they are removed from the aircraft. Additional emphasis is usually given to the ultrahigh-strength steel parts of seats. As with all aircraft parts, corrosion could weaken the structural soundness of a seat. Maintenance personnel should give worn paint finishes and those showing signs of superficial corrosion immediate attention, as specified in the applicable MIM, because other problems not yet visible may be present. They should touch up cockpit fasteners with dull, black paint to prevent cockpit glare. Refer to NAVAIR 01-1 A-509 for more information. Intake and Exhaust Trail Areas Airborne dirt and dust and bits of gravel from runways constantly erode engine frontal areas and cooling air vents. Rain erosion removes the protective finish on intake and exhaust areas (fig. 4-21). In addition, areas such as air intake ducts and cooler radiator cores are not painted. Engine accessory mounting bases usually have small areas of unpainted magnesium or aluminum on the machined mounting surfaces. With moist, salt-laden air constantly flowing over these surfaces, they are prime sources of a corrosive attack (fig. 4-22). When maintenance 205.165 Figure 4-22.—Corrosion in air intake duct. 4-31

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personnel inspect such areas, they should also inspect all sections in the cooling air path, giving special attention to obstructions and crevices where salt deposits may build up during marine operations. Corrosion must be checked in its early stages and paint touch-up and hard-film, preservative coatings must be maintained intact. Jet exhaust deposits are very corrosive. These deposits are particularly troublesome where gaps. seams, hinges, and fairings are located down the exhaust path, and where the deposits may be trapped and not reached by normal cleaning methods. When inspecting these surfaces, maintenance personnel should give special attention to the areas indicated in figure 4-23. Maintenance personnel should also include in their inspection procedures the removal of fairings and access panels located in the exhaust path. JATO, Rocket, and Gun Blast Areas Surfaces located in the path of JATO, rocket, and gun blasts are particularly subject to corrosive attack and decay (fig. 4-24). In addition to the corrosive effect of the gases and exhaust deposits, protective finishes are often blistered by heat and blasted away by high-velocity gases. Also, spent shell casings or solid particles from gun and rocket exhausts abrade finishes. Maintenance personnel should watch these areas for corrosion and clean the finishes carefully after firing operations. Bilge Areas Bilge areas are common trouble spots on all aircraft. One example of a bilge area is the engine bay area. Bilge areas are natural collection points for waste. hydraulic fluids, water, dirt, loose fasteners, drill shavings, and other debris. Oil puddles often mask small quantities of water, which settle to the bottom and set up hidden corrosion cells. Keeping bilge areas free of extraneous material, including oil, is the best insurance against corrosion. Wheel Wells and Landing Gear The wheel well area probably receives more punishment than any other area on the aircraft. It is exposed to mud, water, salt, gravel, and other flying debris from runways during flight operations. It is open to salt water and salt spray when the aircraft is parked aboard ship. Because of the many complicated shapes, assemblies, and fittings in the area, complete coverage with a protectile paint film is difficult to attain. Because of the heat generated from braking, Figure 4-23.—Exhaust trail corrosion points. 4-32

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Figure 4-24.—Gun blast area corrosion points. preservative coatings are not used on jet aircraft landing gear wheels. During inspections, maintenance personnel should pay particular attention to the following areas: Magnesium wheels, especially around bolt heads, lugs, and wheel well areas Exposed metal tubing, especially at nuts and ferrules, and under clamps and identification tapes Exposed connectors, such as indicator switches and other electrical equipment Crevices between stiffeners, ribs, and lower skin surfaces, which are typical water and debris traps Water Entrapment Areas Aircraft have drains installed in areas where water may collect. However, these drains may not be effective either because of improper location or because they are plugged by sealants, fasteners, dirt, grease, and debris. Daily inspection of drains is a standard requirement, especially aboard ship. Q57. Cockpit fasteners should be touched up with what color paint? Q58. In water entrapment areas of an aircraft, drains are required to be inspected how often? Wing Fold, Flap, and Speed Brake Recesses Flap and speed brake recesses are potential corrosion problem areas because they are normally closed when on the ground. Dirt and water may collect and go unnoticed. Wing fold areas contain complicated shapes and assemblies that are difficult to cover with a protective paint coating or preservative film; thus, corrosion is present. Wing fold areas are extra vulnerable to salt spray when wings are folded aboard ship. To thoroughly inspect this area, maintenance personnel should use a mirror to check the back sides of tubing and fittings. Also, they should pay particular attention to aluminum alloy, wing lock fittings (such as those used in some current aircraft models). External Skin Areas Most external aircraft surfaces are ordinarily covered with protective paint coatings and are readily visible or available for inspection and maintenance. Even here, certain types of configurations or combinations of materials can cause trouble under shipboard operating conditions and require special attention. Magnesium skin, when painted over, is not visibly different from any other painted metal surface. Magnesium surfaces are identified in the applicable structural repair manual. When an aircraft contains 4-33

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magnesium skin panels, maintenance personnel must give special attention to these panels during inspections for corrosion. Some aircraft have steel fasteners installed through magnesium skin with only protective finishes under the fastener heads or tapes over the surface for insulation. In addition, paint coatings are thin at trimmed edges and comers. These conditions, coupled with magnesium’s sensitivity to saltwater attack, present a potential corrosion problem whenever magnesium is used. Therefore, maintenance personnel must inspect all magnesium skin surfaces for corrosion, giving special attention to edges, areas around fasteners, and cracked, chipped, or missing paint. The entrance and entrapment of corrosive agents between the layers of metal cause corrosion of spot-welded skins. (See figure 4-25.) Some of the corrosion may be caused originally by fabrication processes, but its progress to the point of skin bulging and spot-weld fracture is the direct result of moisture or salt water working its way in through open gaps and seams. The first indication of this type of corrosion is the appearance of corrosion products at the crevices where the corrosive agents entered. Corrosion may appear at the external or internal faying (closely joined) surfaces, but it is usually more prevalent on external areas. More advanced corrosive attack causes skin buckling and eventual spot-weld fracture. Maintenance personnel should detect skin buckling in its early stages by sighting along spot-welded seams or by using a straightedge. Piano-Type Hinges Figure 4-26 shows the effect of corrosion on the piano hinges used on aircraft. These are prime spots for corrosion to develop due to the dissimilar metal contact between the steel pin and aluminum hinge tangs. They also natural traps for dirt, salt, and moisture. When used on access doors and plates, these hinges tend to freeze in place because they are opened only during periodic inspections. While inspecting for corrosion of these hinges, maintenance personnel should lubricate the hinge and move the hinge back and forth several times to ensure complete penetration of the lubricant. RECOGNIZING AND ELIMINATING CORROSION One of the problems you will have as a maintenance crew member is recognizing and combating corrosion on different materials. The following paragraphs include brief descriptions of typical corrosion product characteristics that are normally found on the materials used in aircraft construction. Also included are the normal procedures for their elimination and prevention. Treating internal corrosion of equipment requires a trained technician, and is normally accomplished at the intermediate- maintenance level. The materials found in avionic equipment, such as gold, silver, tin, solder, and copper alloys, are prone to many forms of corrosion. The treatment for corrosion involving these materials can be found in NAVAIR 16-l-540. When in-depth information is needed about structural corrosion, refer to NAVAIR 01-1A-509. Table 4-2 identifies the Figure 4-25.—Spot-welded skin corrosion points. 4-34

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Table 4-2.—Corrosion of Metals—Nature and Appearance of Corrosion Products ALLOY TYPE OF ATTACK TO WHICH APPEARANCE OF ALLOY IS SUSCEPTIBLE CORROSION PRODUCT Aluminum Alloy Surface pitting, intergranular, White to gray powder. exfoliation, stress corrosion, fatigue cracking and fretting. Titanium Alloy Highly corrosion resistant. Extended No visible corrosion products at low or repeated contact with chlorinated temperature. Colored surface oxides solvents may result in degradation develop above 700°F. of the metal's structural properties. Magnesium Alloy Highly susceptible to pitting. White powder snowlike mounds and white spots on the surface. Carbon and Low-Alloy Steel Surface oxidation and pitting, Reddish-brown oxide (Rust). surface and intergranular. Stainless Steel Crevice/concentration cell Rough surface; sometimes a red, (300-400 series) corrosion; some pitting in marine brown, or black stain. environments; corrosion cracking; intergranular corrosion (300 series) and surface corrosion (400 series). Nickel-base Alloy Generally has good Green powdery deposit. (Inconel, Monel) corrosion-resistant qualities; susceptible to pitting in seawater. Copper-base Alloy Surface and intergranular corrosion. Blue or blue-green powdery deposit. Brass, Bronze Cadmium (protective plating for Good corrosion resistance. Will White powdery deposit to steel) cause embrittlement if not properly brown/black mottling of the surface. applied. Chromium (wear-resistant plating Subject to pitting in chloride Chromium being cathodic to steel, for steel) environments. does not corrode itself, but promotes rusting of steel where pits occur in the coating. Silver Will tarnish in presence of sulfur. Brown to black film. Gold Highly corrosion resistant. Deposits cause darkening of reflective surfaces. Tin Subject to whisker growth. Whiskerlike deposits. nature and appearance of corrosion products found on the metals used in aircraft construction. Iron and Steel Possibly the best known and the most easily recognized form of metals corrosion is the familiar reddish-colored iron rust. When iron and its alloys corrode, dark iron oxide coatings usually form first. These coatings, such as heat scale on steel sheet stock, may protect iron surfaces. However, if enough oxygen and moisture are present, the iron oxide is soon converted to hydrated ferric oxide, commonly known as iron rust. Iron and steel are used in avionic equipment as component leads, magnetic shields, transformer cores, racks, and general hardware. Steel and iron hardware used in aircraft construction is usually plated with nickel, tin, or cadmium. Aluminum Aluminum and its alloys are used many places in aircraft construction, including ejection seats, chassis 4-35

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205.200 Figure 4-26.—Hinge corrosion points. structures in avionic equipment, and the skin of the aircraft. Because of its wide use, you must be able to recognize and take the proper corrective action whenever corrosion is detected or suspected. Aluminum and its alloys are subject to a wide range of corrosive attack, varying from general etching of the surfaces to penetrating attacks along the internal grain boundaries of the metal. The corrosion products (fig. 4-27) appear as white-to-gray powdery deposits that have greater volume than the original metal. In its early stages, aluminum corrosion is evident as a general etching, pitting, or roughness of the surface. The surface attack progresses quite slowly at first; however, the attack will accelerate if the corroding material is not given immediate attention. Paint coatings mask evidence of corrosion, but because the corrosion products have a greater volume, corrosion will show up as blisters, flakes, chips, lumps, or other irregularities in the paint coating. Often, white or gray streaks of corrosion products become readily apparent at breaks in the paint film. Maintenance personnel should investigate such signs further to determine the extent that corrosion has progressed. There are three types of aluminum surfaces insofar as corrosion removal is concerned. They are clad, anodized, and exfoliated aluminum surfaces. Clad Aluminum Surfaces. Pure aluminum has considerable corrosion resistance compared to aluminum alloys. but it has little or no structural strength. An extremely thin sheet of pure aluminum laminated onto each side of an aluminum alloy sheet improves the corrosion resistance with little impairment of strength. The trade name of this aluminum laminate, as originated by the Aluminum Company of America, is Alcad. From this trade name the adjective clad and the verb cladding have been derived. An example of clad aluminum is the surface of unpainted aircraft. Not all aircraft sheet aluminum is clad, especially those alloy sheets from which small brackets, gussets, and fittings are made. The pure aluminum is very soft, and fabrication processes would severely damage or destroy the clad surfaces. To remove corrosion from clad surfaces, the corroded areas should be hand polished with MIL-P-6888 metal polish. It effectively removes stains and produces a high-gloss, lasting polish on unpainted clad surfaces. During the polishing operation, you should take care to avoid mechanical 4-36

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205.166 Figure 4-27.—Aluminum corrosion products. removal of the protective clad layer and exposure of the more susceptible, but stronger, aluminum alloy base. If there is any superficial corrosion present, you should treat it by wiping down the surface with an inhibitive material, such as the Chemical Surface Films for Aluminum Alloy, available under specification MIL-C-81706. Anodized Aluminum Surfaces. Nonclad aluminum alloys are the primary type of aluminum used on naval aircraft. Anodizing is the most common surface treatment of nonclad aluminum alloy surfaces. In anodizing aluminum alloys, the alloy sheet or casting is the positive pole in an electrolytic bath in which an oxidizing agent produces an aluminum oxide film on the metal surface. This aluminum oxide is naturally protective, and anodizing merely increases the thickness and density of the natural oxide film. When this coating is damaged in service, it can only be partially restored by chemical surface treatments. Therefore, when processing anodized surfaces, including corrosion removal, you should avoid destruction of the oxide film. Aluminum wool (nylon webbing impregnated with aluminum oxide abrasive) or fiber bristle brushes are the approved tools for cleaning anodized surfaces. The use of steel wool, steel wire brushes, or harsh abrasive materials on aluminum surfaces is prohibited. A buffed or wire brush finish produced by any means is also prohibited. Otherwise, anodized surfaces are treated in much the same manner as other aluminum finishes. Exfoliated Surfaces. As previously described, exfoliation is a separation along the grain boundaries of metal and is caused by intergranular corrosion. More severe procedures must be used when intergranular corrosion is present. All corrosion products and visible delaminated metal layers must be removed by mechanical means to determine the extent of destruction and to evaluate the remaining structural strength of the component. Maintenance personnel use metal scrapers, rotary tiles, and other tools to assure that all corrosion products are removed and that only structurally sound aluminum remains. Maintenance personnel should inspect the area with a 5- to 10-power magnifying glass or use a dye penetrant to determine if all unsound metal and corrosion products have been removed. When all corrosion products have been removed, maintenance personnel should blend or smooth out any rough edges, even if it involves the removal of more metal. Grinding, where required, is best done by using abrasive nylon wheels into which tiny particles of aluminum oxide abrasives have been impregnated. Chemical treatment of exposed surfaces is applied in the same manner as any other aluminum surface. An aeronautical engineer should evaluate any loss of structural strength in critical areas. This is particularly true if the damage exceeds the permissible limits established in the structural repair manual for the aircraft model involved. Magnesium Magnesium and its alloys have limited use in aircraft structural construction. However, they are used extensively throughout avionic systems as antennas, structures, chassis, supports, and frames. Magnesium, without a protective coating, is highly susceptible to corrosion when exposed to marine environments. Magnesium forms a strong anodic galvanic cell with every other metal and is ALWAYS the one attacked. Magnesium is subject to direct acid 4-37

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attack, deep pitting, stress corrosion, intergranular, and galvanic corrosion. Corrosion of magnesium or its alloys forms white, powdery, snowlike mounds. The deposits tend to raise slightly. and the corrosion spreads rapidly. When magnesium corrosion is detected, it requires immediate attention or the corrosion will spread throughout the entire structure. Magnesium corrosion reprotection involves the maximum removal of corrosion products, the partial restoration of surface coatings by chemical treatment, and a reapplication of protective coatings. After maintenance personnel clean the surface and strip the paint, (if any,) they break loose and remove as much of the corrosion products as possible. They do this by using a pneumatic drill with an abrasive wheel or a Vacu-Blast Dry Honing Machine with glass beads. Steel wire brushes. Carborundum™ abrasives, or steel-cutting tools should NOT be used. After corrosion removal, maintenance personnel treat the surface with specification MIL-M-3171 (type VI) chemical treatment solution, as outlined in the NAVAIR 01-1A-509. Then restore the protective paint film. If extensive removal of corrosion products from a structural casting was involved, a decision from a structural engineer may be necessary to evaluate the adequacy of the structural strength remaining. Structural repair manuals for the aircraft models involved usually include tolerance limits for dimensions of critical structural members. They should be referred to if any question of safety of flight is involved. Copper and Copper Alloys Copper and its alloys are generally corrosion resistant, although the products of corrosive attack on copper are commonly known. Sometimes copper or copper-alloy surfaces will tarnish to a dull gray-green color, and the surface may still be smooth. This discoloration is the result of the formation of a fine-grained, copper oxide crust called “patina.” The patina, in itself, offers good protection for the underlying metal in ordinary situations. However, exposure of copper and copper alloys to moisture or salt spray causes the formation of blue or green salts, indicating active corrosion. These salts form over the patina since this crust is not totally moistureproof. Copper alloys used in aircraft have a cadmium-plated finish to prevent surface straining and decay. Copper and copper-based alloys are used in avionic systems as contacts, springs, connectors, printed circuit board runs, and wires. Copper and copper-based alloys (brass and bronze) are resistant to atmospheric corrosion. However, copper is cathodic to iron, steel, aluminum, and magnesium when in electrical contact with these metals. Maintenance personnel can remove corrosion products by using a pneumatic drill with an abrasive wheel or, as an alternate method, a typewriter eraser (ZZ-E-661. type I or III), depending upon the situation. Copper and copper alloys used in avionic equipment are not usually painted. Cadmium and Zinc Cadmium is used as a coating to protect the part to which it is applied. It also provides a compatible surface when the part is in contact with other materials. The cadmium plate supplies sacrificial protection to the underlying metal because of its greater activity. That is, during the time it is protecting the base metal, the cadmium is intentionally being consumed. It functions in the same way that an active magnesium rod inserted in the water system protects the piping of a hot-water heater. The cadmium becomes anodic and is attacked first, leaving the base metal free of corrosion. Zinc coatings are used for the same purpose, but to a lesser extent in aircraft. Attack is evident by white-to-brown-to-black mottling of the cadmium surfaces. These indications DO NOT indicate decay of the base metal and should NEVER be removed for appearance sake alone. Until the characteristic colors peculiar to corrosion of the base metal appear, no steps should be taken, Cadmium is usually used on bolts as a sacrificial metal to protect the base metal. Zinc is used in avionic/electronic equipment for the same general purpose. Maintenance personne1 remove corrosion products by rubbing lightly with stainless steel wool, abrasive impregnated webbing, or 320-grit or finer aluminum oxide abrasive paper. They do not remove the undamaged cadmium plate adjacent to the corroded area; this will reduce the amount of protection for the underlying base metal. Wire brushes are not used on cadmium-plated surfaces since they will remove more plating than corrosion. After removing corrosion products from cadmium-plated surfaces, maintenance personnel apply a protective coating to retard the corrosive attack. 4-38

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Nickel and Chromium Alloys Nickel and chromium alloys are also used as protective agents in the form of electroplated coatings. Also, they are used as alloying constituents with iron in stainless steels, such as the wear surfaces of aircraft struts. Nickel and chromium plates protect by forming a physical, noncorrosive barrier over the steel. Electroplated coatings, particularly chromium on steel, are slightly porous, and corrosion eventually starts at these pores or pin holes unless a supplementary coating is applied and maintained. Titanium Titanium is often used in engine exhaust areas. Titanium is a highly corrosion-resistant metal. However, it can greatly accelerate corrosion of dissimilar metal coupled to it. Insulation between titanium and other metals is necessary to prevent dissimilar metal attack on the other metal. Maintenance personnel must frequently inspect such areas to make sure that insulation failure has not allowed corrosion to begin. Q59. Q60. Q61. Q62. Q63. Q64. Q65. Q66. Q67. Q68. What publication should you refer to for information about structural corrosion? Hydrated ferric oxide is commonly known as what kind of corrosion? What are the three types of aluminum surfaces insofar as corrosion removal is concerned? How should you remove corrosion from clad aluminum surfaces? What is the primary type of aluminum used on naval aircraft? What are the approved tools for cleaning anodized aluminum surfaces? Who should evaluate any loss of structural strength in critical areas of an aircraft? What manual should you refer to for tolerance limits for dimensions of critical structural members? Copper and copper-based alloys are used in avionic systems for what purpose? Where is titanium most often used on a aircraft? CORROSION REMOVAL AND TREATMENT LEARNING OBJECTIVE: Describe the methods of removing and treating corrosion. Once corrosion is detected, a specific and immediate program for corrective treatment is required. A complete treatment involves paint removal and cleaning of all corroded areas, removal of corrosion products, restoration of protective, surface-treatment films, and immediate application of protective coating and paint finishes. Each type of corrosion has its own peculiarities and requires special treatment. Corrosion should always be removed by the mildest means available. CORROSION REMOVAL Before starting any corrosion removal, you must conduct an inspection and evaluation of the suspected area. When you inspect an aircraft or a particular area of an aircraft for corrosion, you should follow the steps listed below. 1. Clean the area thoroughly. 2. If an area is suspected of having corrosion, visually inspect the area by using a magnifying glass. 3. To preclude metal damage, remove paint chemically from areas suspected of having underlying hidden corrosion. Use abrasive paint removal techniques only when corrosive products are observed. 4. After removing the paint, use a magnifying glass to determine the extent of the damage, especially if there is evidence of corrosion on critical parts. Corrosion cracks must be detected as early as possible. 5. Refer to the applicable structural repair manual (SRM) or MIM for damage limits. Metal loss damage is accumulative. When assessing corrosion damage, consider prior metal loss, including areas on the opposite side of the part. Propellers and helicopter blades have critical balance requirements. Refer to the propeller and blade manuals that apply for the evaluation and repair limits of corrosion, erosion, and abrasive damage. After the aircraft or aircraft part has been inspected, the extent of the corrosion damage must be correctly evaluated. The severity of corrosion damage is grouped into the following categories: Light corrosion. This type of damage is defined as a protective coating that is scarred or etched by light 4-39

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surface corrosion. characterized by discolorization and pitting to a depth of approximately, 1-mil (0.001 inch) maximum. This type of damage can normally be removed by light hand sanding. Moderate corrosion. This looks like light corrosion except that there may be some blisters or evidence of scaling and flaking of the coating or paint system. The pitting depths may be as deep as 10 mils (0.010 inch). This type of damage is normally removed by extensive hand sanding or light mechanical sanding. Severe corrosion. This type of corrosion has a general appearance that may be similar to moderate corrosion with severe intergranular corrosion, blistering exfoliation, scaling, or flaking. The pitting depths are deeper than 10 mils (0.010 inch). This damage must be removed by extensive mechanical sanding and grinding. Repairable damage. When corrosion damage exceeds the limits of the applicable MIM or SRM, it is classified as repairable damage. The use of the affected part may be continued after repair at a cognizant field activity (CFA). Nonrepairable damage. When corrosion damage exceeds the established repair limits and requires replacement of the affected parts or special depot-level repair, it is classified as nonrepairable damage. MECHANICAL CORROSION REMOVAL The most effective mechanical methods of removing corrosion with the least removal of the metal are vapor blasting, soft-grit blasting, and dry, vacuum blasting. For use on assembled aircraft, a portable unit, such as the VACU-Blast Dry Honing Machine, is the most desirable. VACU-Blast Dry Honer The VACU-Blast Dry Honing Machine is a portable, air-operated, self-contained, lightweight unit that uses the dry vacuum return system. Dry honing is the only approved blasting method of removing corrosion on assembled aircraft. With this machine, the work is visible, and metal removal can be held to closer limits. The machine is air-operated, and can be used in shore-based or shipboard operations. The dry honing machine (fig. 4-28) is composed of the following principal components mounted on a two-wheel carriage assembly: A hose rack and storage compartment is provided on the front of the dry honing machine for storage of hoses, brushes, and accessories. The dry honing machine can cause damage to aircraft components and systems if used improperly. Small quantities of abrasives will escape from the blast nozzle during normal use; therefore, the equipment must not be used where the abrasives may contaminate systems or components. The following are precautions you should use when working with this machine: Do not use on engines, gearboxes, or other oil lubricating systems. Do not use on fuel, hydraulic, or oxygen system components. Mask all vent susceptible systems when blasting near them to prevent possible contamination. Use only on exterior surfaces or parts that have been removed from the airframe to prevent possible contamination of interior areas. Do not use on airframe skins or structural parts that are exposed to more than 500°F in service. Do not blast Metallite or honeycomb panels. Q69. What must you do before starting corrosion removal? Q70. How should you remove moderate corrosion? Q71. What is the most desirable method of mechanical corrosion removal? Abrasive Wheel An abrasive wheel can be used to remove severe corrosion (intergranular or exfoliation) on thick metal. The abrasive wheel is composed of nonwoven nylon, resin reinforced. The wheel is mounted on a mandrel assembly and driven by a pneumatic drill motor. Eye protection must be worn when an abrasive wheel is operated. CAUTION After removal of exfoliation corrosion by abrasive wheel, VACU-Blast area with glass beads to ensure removal of all corrosion. Failure to do so will result in the formation of tiny bubbles or flakes. 4-40

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Figure 4-28.—VACU-Blast dry honing machine. 4-41

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SUPPORT EQUIPMENT (SE) CORROSION REMOVAL AND SURFACE PREPARATION The following text discusses surface preparation as well as mechanical and chemical paint and corrosion removal methods for SE. They are listed in order from the most effective or preferred to the least effective and not preferred. Each SE maintenance station develops the procedures for operating surface preparation equipment according to the applicable MIMs. The key to achieving a successful, long-lasting coating system lies in good bonding between coating and metallic surfaces of SE. Paint will not bond to a surface that is poorly prepared. Dirt, oil, grease, corrosion by-products, moisture, and other contaminants prevent complete contact between paint and base metal. In addition, a metallic surface must be roughened to enable the paint system to bond to the surface. This roughened or anchor pattern can be produced by mechanical means or by chemical etchings. You should remove corrosion, scale, and old paint from SE by the least destructive method. Where simple touch-up painting is required. feather the edges of existing sound paint with light sanding to provide an anchor for the touch-up paint. You must apply the initial paint to SE as soon as possible following surface preparation. A prolonged lapse in time between surface preparation and painting allows corrosion to form on the prepared surface. This corrosion will cause later coating system failure. REMOVING DIRT, OIL, AND GREASE The first step in surface preparation is the removal of dirt, salt, lubricants. hydraulic oil, and other surface contaminants from SE. When grease and oil are present during abrasive blasting, grinding, or wire brushing, they will spread out over the treated surface and disrupt the coating bond. The cleaning method that you use depends on the type of soil, its extent, and the available cleaning equipment. Detergent cleaning, solvent cleaning, emulsifiable solvent cleaning, and acid cleaning are cleaning or degreasing methods. Detergents and solvents are highly effective in attacking and dissolving grease and oil on metal surfaces of SE. Most solvents can be either applied by vapor degreasing equipment or by wiping. Solvents are specially useful for cleaning small parts and spot-cleaning jobs. Disadvantages of degreasers lie in their toxicity and flammability. Many solvents are particularly dangerous when used on oxygen service equipment. Emulsifiable solvent (solvents suspended in a gelatinlike medium) cleaning is an effective cleaning method for removing heavy oil, grease, wax, and other contaminants of SE. Acid cleaning combines the forces of oil solvents and detergent cleaners in removing grease, oil, light rust, and other contaminants. The method is useful on the heavy steel structures of SE where surface etching is required. This cleaning method requires a thorough rinse with clean water. MECHANICAL CORROSION REMOVAL ON SUPPORT EQUIPMENT (SE) Abrasive or grit blasting is the preferred surface preparation method for many of the components of SE. Such blasting provides the clean anchor pattern needed by most coating systems. Wet abrasive blasting is preferred to dry blasting. Before blasting, disassemble the components according to the applicable technical manual. Mask all areas that should not be blasted, such as tapped holes, key ways, machined surfaces, reflectors, lights, and gauges. When using abrasive blasting equipment, you must wear protective clothing, face shield or safety goggles, and a respirator. Wet Abrasive Blasting Water blasting is a technique that requires high-pressure producing equipment. It involves the propelling of water and blasting beads. The water blast method removes surface chemical contaminants, deteriorated paint, grease accumulations, oil, and mastic materials from SE. NOTE: You must use Sodium Nitrite MIL-S-24521 during the abrasive process to prevent flash rusting. The Hydroblaster or other water blast machines can be dangerous if not handled properly or with sufficient safeguards. 4-42

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Dry Abrasive Blasting Dry abrasive blasting involves propelling abrasive particles against the metallic surface by either high-pressure air or spinning paddle wheel. The striking of these particles against the metal abrades away deteriorated paint and scale. Many abrasive blast machines (portable dry-honing machines) reclaim used grit by cleaning and sifting out dirt, scale, and damaged grit. (See figure 4-28.) Grit that has been recycled after use on steel, brass, bronze, or copper-nickel should not be used on aluminum. Do not blast aluminum with steel or copper slag or chilled iron grit. Table 4-3 lists some common abrasive materials and grit sizes. CLEANING SURFACES WITH POWER TOOLS Power tool cleaning includes devices that impact the metallic surface with an abrasive substance or mechanical object. Impact tools, powered wire brushes, and disk sanders are common power tool cleaners for SE. Usually, electric or pneumatic disk sanders abrade the metal surface of SE with coarse to fine grit. When used with the needle gun, the disk sander can produce a uniform anchor pattern of very closely spaced scratches. WARNING When using abrasive power hand tools, you must wear eye protection to prevent serious injury. Q72. What is the preferred surface preparation method for many of the components of support equipment? Q73. What should you use during the abrasive process to prevent flash rusting? CORROSION DAMAGE LIMITS LEARNING OBJECTIVE: Recognize the limits in removing corrosion damage. Impact tools, such as the needle gun (pneumatic descaler), provide a rapid means for removing rust and old paint from metal surfaces of SE. These tools must NEVER be used on aluminum. A wire brush powered pneumatically or by electric motor is a method for removing small amounts of paint and rust from SE. Often, the overextended use of a wire brush results in a metal surface that is polished to a glossy appearance. A polished surface produces a poor anchor pattern for paint bonding. Corrosion damage limits refer to the amount of metal that may be removed from a corroded part without impairing the strength and function of the part. When removing corrosion, maintenance personnel must be very careful not to remove more of the metal than is necessary to ensure complete removal of corrosion. Figure 4-29 shows the maximum corrosion depths allowed on the various components of the nose landing gear. When damage exceeds the limits specified in the SRM or the corrosion control section of the MIM, the affected part must be replaced if structural repair of the damage is not possible. Table 4-3.—Recommended Grit for Steel and Aluminum TYPE OF RECYCLING NON-RECYCLING METAL BLASTED GRIT SAE PRES GRIT SAE PRES MESH PSI MESH PSI Steel Angular silica 20/40 75 Silica sand 20/40 75 Sand Crushed garnet 20/40 75 Crushed garnet 20/40 75 Aluminum oxide 20/50 50 Aluminum Silica sand 20/40 75 Silica sand 20/40 75 Aluminum oxide 20/50 50 Crushed garnet 20/40 75 Crushed garnet 20/40 75 4-43

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Figure 4-29.—Nose gear maximum corrosion depths. 4-44

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Q74. Information regarding corrosion removal limitations can be found in what publications? CHEMICAL SURFACE TREATMENT LEARNING OBJECTIVE: Define the purpose for chemically preparing a surface for priming and painting. Chemical conversion coatings increase a surface’s resistance to corrosion and improve paint bonding on the surface. The metal to be treated must be cleaned to a water breakfree surface (fig. 4-30). Metal surfaces not free of water breaks must be recleaned with a solution of 1 part MIL-C-43616 or MIL-C-25769 aircraft cleaning compound to 16 parts of water, and then rinsed with water. Surfaces that have been waxed, particularly with silicone wax, may require special cleaning. After cleaning and removal of surface oxides, aluminum should be treated with MIL-C-81706 and magnesium with MIL-M-3171, type VI, chemical conversion coating material. 214.248 Figure 4-30.—Water break comparison. CAUTION Personnel must wear protective clothing, rubber gloves, and chemical goggles when using a solution of MIL-C-81706 and MIL- M-3171 or serious injury could result. Apply these chemical conversion coatings immediately after cleaning the surface to a water breakfree surface and while the surface is still wet. Apply these coatings by brush, nonatomizing spray, or sponge stick moistener. The sponge stick moistener is particularly useful for small areas. Soluble salt residues that remain on the surface after treatment accelerate corrosion and can cause blistering of paint finishes. Thus, complete rinsing with fresh water following the chemical treatment is very important. Flush the chemical with free-flowing water only. Allow the chemical conversion coated surface to dry (usually 30 minutes) before painting. Do NOT wipe the surface with a damp cloth or brush, as this will degrade or remove the chemical conversion coating. Chemical conversion coatings are often damaged during aircraft maintenance, or they may be contaminated by grease, oil, or other foreign matter. Therefore, the treated surface should be painted soon after treating to obtain the best results. CHEMICAL CONVERSION OF ALUMINUM ALLOYS The procedure to be used for the chemical conversion of aluminum alloys is as follows: Apply the conversion coating material, MIL-C-81706 (Form V [powdered] is preferred, Form III [premixed] is an alternate), until you obtain a golden iridescent color. Immediately rinse the chemical from the surface with large amounts of fresh water when you obtain the proper color conversion. This rinsing stops the chemical action and minimizes solution entrapment. Failure to rinse may accelerate corrosion and reduce paint bonding. If a long period of contact before rinsing is allowed, a powdery, coated surface may be the result. CHEMICAL CONVERSION OF MAGNESIUM ALLOYS The procedure for the chemical conversion of magnesium alloys is as follows: Apply the conversion 4-45

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coating material MIL-M-3171 until you obtain a greenish-brown or brass-colored yellow color. For a proper conversion coating, keep the surface wet with the specified solution until you obtain the desired color. Rinse with fresh water. Remove any excess conversion coating solution that collects into pools within the aircraft. Some magnesium parts in later model aircraft were originally protected by a proprietary (held under patent) electrolytic process. One process is identified by the brown to mottled gray appearance of the unpainted surface. Another process will appear as a green to grayish-green color. These coatings are thicker than those applied by the immersion or brush method, such as MIL-M-3171. The electrolytic finish cannot be restored in the field. Therefore, when failure of the coating occurs, you should remove corrosion and touch up the bare magnesium with MIL-M-3171 chemical treatment solution. You should minimize removal of the electrolytic coatings, as they afford greater protection than the replacement coatings. Q75. What is the purpose for chemically treating a surface for painting? Q76. When failure of the coating occurs, you should remove corrosion and touch up the bare magnesium with what chemical treatment solution? AIRCRAFT PAINTING AND COMPONENT TOUCH-UP LEARNING OBJECTIVE: Identify the materials used and procedures for painting aircraft. The amount of paint touch-up done at organizational- and intermediate-level maintenance varies widely. The amount depends upon the activity involved, the availability of facilities, and the area of operations. The primary objective of any paint finish is the protection of the exposed surface against decay. There are secondary reasons for particular paint schemes. Glare is reduced by nonspecular (not mirrorlike) coatings. White or light-colored, high-gloss finishes reduce heat absorption. Camouflage, high visibility, or special identification marking requirements are met by various paint schemes. REPAINTING SHOULD NOT BE DONE FOR APPEARANCE SAKE ONLY. A faded or stained but well-bonded paint finish is better than a fresh touch-up treatment applied over dirt, corrosion products, or other contaminants. Complete refinishing (particularly under field conditions) should be restricted to those areas where existing paint finishes have degraded until they fail to perform their protective function. However, the organizational and intermediate levels of maintenance should evaluate maintenance and repair of paint finishes. This should be done at the time of aircraft receipt and through constant surveillance and maintenance of finishes during an aircraft’s service tour. Maintenance also should make final recommendations for refinishing an aircraft when the aircraft is scheduled for standard depot-level maintenance (SDLM). General safety precautions should be followed when you paint and when you use special types of paints. These precautions include the following: No eating, drinking, or smoking is allowed in areas where paint or solvent is being used. Prolonged breathing of vapors from organic solvent is dangerous. Prolonged skin contact with organic solvents or materials containing organic solvents can have a toxic effect on the affected skin area. PAINT REMOVAL Paint removal operations at the organizational and intermediate levels of maintenance are usually confined to small areas, or possibly a whole panel. In all cases, the procedures outlined in the MIM that applies should be observed. General stripping procedures are contained in NAVAIR 01-1A-509. Materials All paint removers are toxic and caustic; therefore, both personnel and material safety precautions must be observed in their use. Personnel should wear eye protection, gloves, and a rubber apron. Paint remover, specification MIL-R-81294, is an epoxy paint remover for use in the field. This remover will strip acrylic and epoxy finishes. Acrylic windows, plastic surfaces, and rubber products are damaged by this material. This material should not be stocked in large quantities as it ages rapidly, degrading the results of stripping action. This paint remover must NOT be used to remove paint from composite materials. 4-46

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Procedures and Precautions The stripping procedures described below are general in nature. When stripping any aircraft surface, you should consult the applicable MIM for the specific procedures to be used. Stripping should be accomplished outside whenever possible. If you must strip aircraft surfaces in a hangar or other enclosure, you should make sure you have adequate ventilation. You should adhere to the following general procedures and precautions during stripping operations: CAUTION Before cleaning and stripping, make sure that the aircraft is properly grounded. This will dissipate any static electricity produced by the cleaning and stripping operations. Where the paint remover may contact adhesives, mask all seals, joints, skin laps, and bonded joints by using the approved tapes and papers. Apply the stripper liberally. Completely cover the surface with a thick layer of stripper with a paint or acid brush. The stripper should not be spread in a thin coat like paint because it will not loosen paint sufficiently for removal, and the remover may dry on the surface of the metal. This would require it to be reapplied. Allow the stripper to remain on the surface long enough for it to wrinkle and lift the paint. This may be from 10 to 40 minutes, depending upon temperature, humidity, and the condition of the paint coat being removed. Reapply paint remover as necessary in the areas where paint remains tight or where the material has dried. Remove loosened paint and residual paint remover by washing and scrubbing the surface with fresh water, fiber scrapers, bristle brushes, and rags. If water spray is available, you should use a low-to-medium pressure stream of water. Apply it directly to the surface while scrubbing the surface. After a thorough cleaning, you should remove masking materials and clean any residual paint from the surface. Rinse with water and clean the area with aircraft cleaning compound (1 part MIL-C-85570 to 9 parts water) to remove paint remover residue. Flap Brush Paint can be mechanically removed with a flap brush. The brush consists of many nonwoven, nonmetallic, nylon flaps bonded to a fiber core. The brush assembly (fig. 4-31) is made up of a flap brush, flanges, and mandrel. Use a NO LOAD 3200 rpm pneumatic drill motor to power the brush. Do not use a flap brush that is worn down to within 2 inches from the center of the hub. Continued use beyond this limit may cause gouging due to loss of flexibility of the fiber. When you use a flap brush, apply minimum pressure to remove the most paint and the least metal. Excessive pressure will cause some paints to melt, gum up, and streak around the area being worked. For safe and efficient operation, the direction of rotation is indicated by an arrow imprinted on the inside of the core. Wear eye protection when operating a flap brush, and consult your maintenance instruction manuals for limitations on corrosion removal. Q77. What is the primary purpose of any paint finish? Q78. When using paint removers, you should wear what type of protective clothing? Q79. What safety precaution must be taken before cleaning and stripping old finishes on aircraft? Q80. What type of motor should you use to power a flap brush? Figure 4-31.—Flap brush and mandrel. 4-47

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SURFACE PREPARATION The effectiveness of any paint finish and its bond to the surface depends upon the careful preparation of the damaged surface before touch-up. The touch-up paint should overlap onto the existing good paint finish. The touch-up materials will not bond to glossy finishes, so the finishes must be prepared. Also, any edges of the existing film will show through the overlap unless they are smoothed out. To break the gloss of existing finishes and to feather (smooth out) the edges for overlap, you should scuff sand by using 240 or 320 grit aluminum oxide cloth. After sanding, use a water rinse to remove the abrasive residues. You should remove any loosened seam sealants in the area to be touched up and replace them as necessary. Also, resecure any loose rubber seals by using the type of adhesive specified in the applicable MIM. Then outline the area to be painted with tape and masking paper, as shown in figure 4-32. This protects the adjoining surfaces from overspraying and unwanted paint buildup. TOUCH-UP PROCEDURES A standardized paint system for O- and I-level painting and paint touch-up is presented in NAVAIR 01-1A-509. Standardized exterior paint touch-up systems for organizational and intermediate levels of maintenance consist of an epoxy primer (MIL-P-23377, type I or type II, as applicable) overcoated with aliphatic polyurethane (MIL-C-85285). Paint systems are identified by a decal or stencil located on the right side of the aft fuselage. Standardized interior paint touch-up systems for O- and I-level maintenance consist of zinc chromate primer (TT-P-1757). Paint materials that are within their original shelf life or within an extended shelf life are preferred. However, if materials are beyond shelf life date, test them by using a small sample of scrap aluminum. The following paragraphs furnish the basic information for identifying and applying the standard touch-up paint systems. Complete information on the types and applications of aircraft paint systems is contained in NAVAIR 01-1A-509. Figure 4-32.—Masking before paint touch-up. Epoxy-Polyamide Primer (MIL-P-23377) The epoxy-polyamide primer is supplied as a two-part kit. Each part must be stirred or shaken thoroughly and separately before they are mixed together. One part contains the pigment particles in an epoxy vehicle. The other part is composed of a clear polyamide solution that functions as a hardener for the epoxy solution. This primer is supplied by various manufacturers. You should mix only as much primer as needed. The storage life of the primer is limited after it is mixed to the amount that can be used in 4 hours. Refer to NAVAIR 01-1A-509 for specifics on mixing these two components. Zinc Chromate Primer Zinc chromate primer (TT-P-1757) is a general-purpose, interior, protective coating for metal surfaces. Depending upon the location, zinc chromate primer may or may not require a topcoat. Zinc chromate primer is easy to apply or remove as it is a single component. There is no thinning required for brush or roller application however, for spray application, thin this primer with MIL-T-81772. Do not use zinc chromate primer on exterior aircraft surfaces, including wheel wells and wing butts, and in areas that are exposed to temperatures exceeding 175°F (79.4°C). Polyurethane Finish Systems You must have a physical examination before you can work with polyurethane coatings. Also, you must 4-48

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have periodic physicals during the time you are working with these coatings. There are two types of polyurethane systems used on naval aircraft-the aliphatic type (used in MIL-C-85285 and TT-P-2756 polyurethane paints) and the aromatic type (used in polyurethane, rain erosion-resistant coatings, MIL-C-85322). These materials present no special hazard to health when cured (dried), but they require special precautions during preparation, application, and curing due to the isocyanate vapors produced. The isocyanates vapors can produce significant irritation to the skin, eyes, and respiratory tract even in very small concentrations. They also may induce allergic sensitization of personnel exposed to their vapors and mists produced during spray applications. Aliphatic polyurethane. MIL-C-85285, is the standard, general-purpose, exterior, protective coating for aircraft surfaces. The polyurethane finish comes in kits that consist of a two-component material resin and a catalyst. The touch-up kits are prethinned and ready for use when they are mixed according to the instructions in the kit. Use aliphatic polyurethane over epoxy polyamide primer and for touch-up and insignia markings over polyurethane paint systems only. Acrylic Lacquer Acrylic lacquer (gloss and camouflage) MIL-L-81352 is the preferred topcoat material for aircraft markings that identify the reporting custodian and for propeller safety stripes. Enamel Finishes Most enamel finishes used on aircraft surfaces are baked finishes that cannot be touched up with the same materials in the field. Minor damage to conventional enamel finishes ordinarily used on engine housings is repaired by touching up with epoxy topcoat material or air-drying enamel. Elastomeric Rain Erosion-Resistant Coating (MIL-C-85322) Elastomeric coatings are used as a coating system to protect exterior laminated plastic parts of high-speed aircraft, missiles, and helicopter rotary blades from rain erosion in flight. They offer good resistance to weather and aromatic fuels in addition to rain erosion. Excellent bonding is obtained after a 7-day drying period. Repair to these coatings in the field is not practical due to this long curing time. Kits are available for repair of coatings where limited touch-up is required. These kits contain a primer, neoprene topcoat, and antistatic coating. If the radome or leading edge coatings are in bad condition, they should be stripped completely and recoated with epoxy primer and acrylic topcoat as a temporary measure. If schedules and conditions permit adequate curing of elastomeric coatings, the original coatings may be replaced. The repair kits are normally bought as an open purchase to ensure that fresh materials are available. Since heat accelerates aging, repair kits should be stored in a cool place or refrigerated. Stripping of fiber glass surfaces should be done according to current maintenance instructions. Elastomeric coatings are toxic and flammable, and must be used with care. PAINTING EQUIPMENT (SPRAY GUNS) The spray gun atomizes the material to be sprayed, and the operator directs and controls the spray pattern through manipulation and minor adjustments of the spray gun. Spray guns are usually classed as either a suction-feed or pressure-feed type. The type of spray gun can be determined by two methods-by the type of container used to hold the paint material and by the method in which the paint is drawn through the air cap assembly. For information on the types of spray guns, refer to NAVAIR 01-1A-509. Suction-Feed Type The suction-feed spray gun is designed for small jobs. The container for the paint is connected to the spray gun by a quick-disconnect fitting, as shown in figure 4-33. The capacity of this container is approximately 1 quart. The fluid tip of this spray gun protrudes through the air cap, as shown in figure 4-34. The air pressure rushing by the fluid tip causes a low-pressure area in front of the tip. This causes paint to be drawn up through the fluid tip, where it is atomized outside the cap by the air pressure. Pressure-Feed Type The pressure-feed spray gun is designed for use on large jobs where a large amount of spray material is to be used. With this type of spray gun, the material is supplied to the gun through a hose from a pressurized tank. This spray gun produces a high volume of spray material metered at a low air pressure. This type of 4-49

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SEALANTS Figure 4-33.—Suction-feed type of spray gun. Figure 4-34.—Suction and pressure fluid tips and air caps. spray equipment eliminates evaporation of the volatile substances of the mixture before they strike the surface because the paint and air are mixed internally. Thus, a wetter coating is applied. CAUTION Many of the sealants discussed in this sec- tion may be flammable or produce toxic vapors. When materials designated as flammable are used, ail sources of ignition must be at least 50 feet away from the work location. Toxic vapors are produced by the evaporation of solvents or the chemical reaction that takes place in the curing sealants. When sealants are used in a confined space, such as a fuel cell, fuselage, wing section, or table or bench operation, adequate local exhaust ventilation must be used. This will reduce the vapors below the maximum allowable concentration and keep them at that level until repairs have been completed. Personnel must NOT eat or smoke when they work with sealants. Sealants are used to prevent the movement of liquid or gas from one point to another. They are used in an aircraft to maintain pressurization in cabin areas, to retain fuel in storage areas, to achieve exterior surface aerodynamic smoothness, and to weatherproof the airframe. Sealants are used in general repair work in the field and for maintenance and restoration of seam integrity in critical areas if structural damage or the use of paint removers has loosened existing sealants. Conditions surrounding the requirements for use of sealants govern the type of sealants to be used. Some sealants are exposed to extremely high or low temperatures. Other sealants are in contact with fuels, lubricants, and so forth. Therefore, sealants are supplied in different consistencies and rates of cure. The basic types of sealants are classified in three general categories-pliable sealants, drying sealants, and curing sealants. Pliable sealants are called “one-part” sealants and are ready for use as packaged. They are solids and change little, if any, during or after application. Solvent is not used in this type of sealant. Therefore, drying is not necessary; and except for normal aging, they remain virtually the same as when first packaged, neither hardening nor shrinking. They bond well to metal, glass, and plastic surfaces. Pliable sealants are used around high-usage access panels and doors, and 4-50

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in areas where pressurized cavities must be maintained. Drying sealants set and cure by evaporation of the solvent. The solvents in these sealants provide the desired consistency for application. Consistency or hardness may change when this type of sealant dries, depending upon the amount of solvent it contains. Shrinkage is a consideration when these sealants are used. Shrinkage occurs upon drying. The degree of shrinkage depends on the proportion of solvents. Catalyst-cured sealants have advantages over drying sealants. They are transformed from a fluid or semifluid state into a solid mass by chemical reaction of physical change rather than by evaporation of a solvent. A chemical catalyst of accelerator is added and thoroughly mixed just before sealant applications. Heat may or may not be used to speed up the curing process. When a catalyst is used, accurate proportioning and thorough mixing of the two components are very important to assure a complete and even cure. Application of Sealants Application of sealants varies according to time element, tools required, and the method of application. However, the following restrictions apply to all sealant applications: Sealants should be used within the approximate application time limits specified by the sealant manufacturer. Sealants should not be applied to metal that is colder than 70°F. Better bonding is obtained and the applied sealant will have less tendency to flow out of place while curing if the metal is warmed to a temperature of 90°F to 100°F before the sealant is applied. Sealants should be discarded immediately when they become too stiff to apply or work readily. Stiff or partially cured sealants do not wet the surface to which they are applied as well as fresh material. This causes uneven bonding. Sealants should not be used for close-fitting (faying) surface applications unless they have just been removed from refrigerated storage or freshly mixed. Brushes, dipping, injection guns, spatulas, and spray guns are the methods used to apply sealants. Figure 4-35 shows (black areas) where sealant is applied to protect some of the most corrosion-prone areas on an F-14 aircraft. The sealant is applied by using the spray, spatula, and brush methods. Sealant MIL-S-81733, type III, is the sealant used most extensively for spray application. If type III sealant cannot be procured, sealant MIL-S-8802, class A, may be used by thinning it to a sprayable consistency by the addition of the correct solvent. When an aircraft is pressure sealed, the sealing materials should be applied as a continuous bead, film, or fillet over the sealed area. Air bubbles, voids, metal chips, or oily contamination prevent an effective seal. Therefore, the success of the sealing operation depends upon the cleanliness of the area and the careful application of the sealant materials. There are various methods of pressure-sealing joints and seams in aircraft. The applicable SRM will specify the method to be used in each application. The sealing of a faying surface is done by brush. The contacting surfaces are coated with the specified sealant. Application of the sealant should be made immediately before the parts are fastened together. Careful planning of work and equipment are necessary so faying surface seals on large assemblies may be closed within the application time limit of the sealant. Once the sealant has been applied, the parts must be joined, the bolts torqued, and the rivets driven all within the application time limit. When insulating tape has been installed between the faying surfaces to prevent contact of dissimilar metals, pressure sealing should be done by fillet sealing. In fillet sealing, the sealant is spread along the seam with a sealant injection gun in about 3-foot increments. Before proceeding to the next increment, the applied portion of the fillet is worked in with a sealant spatula or tool (fig. 4-36). This working of the sealant is done to till in all voids in the seam and to eliminate most air bubbles. The care used in working out the air bubbles determines the leakfree service life of the sealant. After the sealant has cured to a tackfree condition, the fillet should be inspected for remaining air bubbles. These air bubbles should be opened and filled with sealant. When a heavy fillet is required, the fillet should be applied in layers. The top layer should fair with the metal. Injection sealing is the pressure filling of openings or voids with a sealant injection gun. The sealant is forced into the opening until it emerges from the opposite side. Voids and cavities are filled by starting with the nozzle of the sealant injection gun at the bottom of the space and tilling as the nozzle is 4-51

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Figure 4-35.—Sealant applied to aircraft exterior surfaces. 4-52

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Figure 4-36.—Applying sealant. withdrawn. An example of injection sealing is the caulking of a leaking fuel cell. Fasteners, such as rivets, Rivnuts, screws, and small bolts, should have a brush coat of sealant over the protruding portion on the pressure side. Washers should have a brush coat of sealant on both sides. Split-type grommets should have sealant brushed into the split before installation. After installation, fillets should be applied to both the base of the grommet and the protruding tube on the pressure side. Sealing Compound (MIL-S-8802). MIL-S-8802 is a temperature-resistant (-65°F to +250°F), two- component, synthetic rubber compound used for sealing and repairing fuel tanks and fuel-cell cavities. It is produced in three classifications. Class Use A For brushing application B For extrusion gun and spatula application C For faying surface sealing Sealing Compound (MIL-S-81733). MIL-S-81733 is an accelerated, room-temperature curing, synthetic rubber compound. It is used in sealing metal components on weapons and aircraft systems for protection against corrosion. This sealant contains a corrosion inhibitor. Figure 4-37 shows MIL-S-81733 sealing compound used to seal an antenna. It comes in four types. Type Applied by Maximum application time in hours I Brush 1/2 Dip 2 II Extrusion 1/2 Gun 2 Spatula 4 III Spray gun 1 IV Brush or Spatula 12 to 48 Figure 4-37.—Typical fleet antenna sealing application. 4-53

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Sealing Compound (MIL-S-8516). MIL-S-8516 is an accelerated, synthetic, rubber sealing compound used for sealing low-voltage electrical connectors, wiring. and other electrical equipment against moisture and corrosion where temperatures do not exceed 200°F. This sealant has very good resistance to fuels, oils, grease, water, and humidity. However, it is NOT authorized for use in engine bays, keel areas, or areas adjacent to bleed-air ducts. It is manufactured in kit form and comes in sizes from 2.5 ounces to 1 quart. MIL-S-8516 is available in three classes with different curing times. Class Curing time in hours 1 24 2 48 3 72 Silicone Rubber Sealant (MIL-S-23586). Room temperature vulcanizing (RTV), silicone rubber sealant is used for sealing small electrical connectors and electrical components that are located in areas where the temperatures are between 200°F and 450°F. This sealant has good resistance to weathering, moisture, and withstands ozone. RTV silicone rubber sealant is available in two types, both used for the same purposes. The two types are type II, class 2, grade A, and type 1, class 1, grade B- 1. Type II, class 2, grade A contains cure volatiles and should be used only in well-ventilated areas. Adhesive Silicon Sealant (MIL-A-46146). Also known as 3145 RTV. A noncorrosive sealant for use on sensitive metals and avionics equipment in areas that are exposed to temperatures between 250°F and 350°F. This sealant comes in 3-, 8-, and 12-ounce tubes. CAUTION Many RTV silicone sealants contain an acetic acid curing agent. These sealants, when in contact with metal, cause rapid corrosion. RTV sealants that contain acetic acid are NOT authorized for use on electronic or elec- trical circuits. They may be identified by the emission of a vinegar odor while in a liquid or curing state. Q81. Complete information on the types and applications of aircraft paint systems is contained in what publication? Q82. After it is mixed, the storage life of epoxy-polyamide primer is limited to the amount that can be used in how many hours? Q83. What is the standard, general-purpose, exterior protective coating for aircraft surfaces? Q84. What are the two classes of spray guns? Q85. When flammable materials are used, all sources of ignition must be at least how far away from the work location? SUMMARY This chapter identifies the manuals and procedures used to detect and combat corrosion on naval aircraft and support equipment. It identifies the types and causes of corrosion. Familiarize yourself with types and uses of cleaning materials and the procedures and materials for preservation and depreservation. This is vital information. 4-54

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ANSWERS TO REVIEW QUESTIONS A1. A2. A3. A4. A5. A6. A 7. A8. A9. A10. A11. A12. A13. A14. A15. A16. A17. A18. A19. A20. A21. They must be kept in specially marked containers. A22. In a separate building or-flammable liquids storeroom. A23. It is applied by spraying, dipping, brushing, or wiping. A24. 1,1,1-trichloroethane. Corrosion reduces the strength and changes the mechanical characteristics of the material. Corrosion control. Weight-to-strength ratio. Metal corrosion, Protection from corrosive environments. Electron flow is established from the cathode to the anode. They speed the corrosion process. Thick sections are more likely to have variations in their composition, particularly if heat-treated during fabrication. Moisture is the single largest contributor to avionics corrosion. NAVAIR 01-1A-509. NAVAIR 16-1-540 provides information on cleaning and corrosion prevention and control of avionics equipment. NAVAIR 15-01-500, Preservation Of Naval Aircraft. General uses for cements, sealants, and coatings. A period of intensive care should follow the deployment cycle to bring the aircraft back up to standard. A good corrosion prevention program. Every 14 days. a. Aircraft is exposed to corrosive fire-extinguishing materials. b. Spilled electrolyte and corrosive deposits are found around battery terminals and battery area. c. The aircraft has been exposed to significant amounts of salt water. d. Salt deposits, relief tube waste, or other contaminants are apparent. e. Fungus growth is apparent. f. Chemical, biological, or radiological contaminants are detected. They must be cleaned or wiped down. Flammability and toxicity Inhaling toxic vapors can seriously affect the brain and central nervous system. 4-55

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A25. A26. A27. A28. A29. A30. A31. A32. A33. A34. A35 A36. A37 A38. A39. A40. A41. A42. A43. A44. A45. A46. A47. A48. A49. a. Apply by wiping or scrubbing the affected area with an acid brush or toothbrush. b. Air dry or oven dry as applicable. c. Do not use on acrylic plastics or acrylic conformal coatings. d. Do not use on unsealed aluminum electrolytic capacitors. Damage may result to end caps and cause leakage. Silicon carbide paper because it is sharp and the individual grains can penetrate steel surfaces. Because it conforms to the surface, the applicator allows easier application of a constant scrubbing pressure on curved skin panels. MIL-C-85570. Select the proper cleaning agent for the method of cleaning chosen. Upward and outward. Dry-cleaning solvent. It is not oxygen compatible and will cause explosion or fire. A polyethylene sheet, polyethylene-coated cloth, or metal foil barrier materials. The maintenance instructions manual (MIM). NAVAIR 01-1A-509. Level I—Short term, up to 60 days. Level II—60 days to 1 year. Level III—Long term, 1 to 8 years. Level I preservation. All three. Grades I, IL and IV. Antifriction bearings, shock-strut pistons, and other bright metal surfaces. It is used when a water-displacing, low temperature, lubricating oil is required. Type III. Level I. Ground Support Equipment Cleaning and Corrosion Control, NAVAIR 17-1-125. Silicone sealant MIL-A-46146, type I, and polysulfide sealant MIL-S-81733 or MIL-S-8802. Uniform or direct surface attack Aluminum and magnesium alloys. White or gray powdery deposit. Avoid the creation of crevices during repair work. Intergranular corrosion is an attack on the grain boundaries of alloys under specific conditions. 4-56

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A50. It is usually the result of faulty design or improper maintenance practices. A51. Stress induced by press-and-shrink fits and those in rivets and bolts. A52. Fatigue corrosion is caused by the combined effect of corrosion and stress applied in cycles to a component. A53. A slight vibration, friction, or slippage between two contacting surfaces that are under stress or heavy load. A54. A55. A56. A57 A58. A59. A60. A61. A62. A63. A64. Steel, aluminum, and magnesium. Applicable periodic maintenance information cards (PMICs). A cathode, an anode, and an electrolyte. Black paint to prevent glare. Daily. NAVAIR 01-1A-509. Iron rust. Clad, anodized, and exfoliated. Hand polish the corroded areas with MIL-P-6888 metal polish. Nonclad aluminum alloys. Aluminum wool or fiber bristle brushes. A65. An aeronautical engineer. A66. Structural repair manuals for the specific aircraft model. A67. Contacts, springs, connectors, printed circuit board runs, and wires. A68. In the engine exhaust areas. A69. A70. A71. A72. A73. A74. A75. A76 A77. A78. A79. A80. Conduct an inspection and evaluation of the suspected area, Extensive hand sanding or light mechanical sanding. VACU-Blast dry honing portable machine. Abrasive or grit blasting. Sodium Nitrite MIL-S-24521. The applicable aircraft Structural Repair Manual (SRM) or the "Corrosion" section of the Maintenance Instruction Manual (MIM) Chemical conversion coatings increase a surfaces resistance to corrosion and improve paint bonding to the surface. MIL-M-3171. The protection of the exposed surfaces against decay. You should wear eye protection, gloves, and a rubber apron. Ensure the aircraft is properly grounded. Use a NO LOAD 3200 rpm pneumatic drill motor. 4-57

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A81. NAVAIR 01-1A-509. A82. 4 hours. A83. Aliphatic polyurethane, MIL-C-85285. A84. Suction feed and pressure-feed spray guns. A85. 50 feet. 4-58

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CHAPTER 5 LINE OPERATIONS AND SPECIAL PROGRAMS One of the busiest, most important and dangerous divisions in a squadron is the line division. Upon reporting to a squadron, no matter your rate or paygrade, you may be assigned to the line division. As an Airman, or third class petty officer, you may become a plane captain. A plane captain has many responsibilities in flight operations and in the day-to-day maintenance of modern aircraft. As a more senior petty officer or a Chief, you may be assigned as the LPO or Branch Chief. It is important for you to know how the line division operates and the safety factors involved with line operations. This chapter briefly outlines some of these crucial factors. ORGANIZATION LEARNING OBJECTIVE: Identify the organization of the line division and define the responsibilities and qualifications of a plane captain. The following text discusses the organization of the line division. Knowledge about the line organization is important because it will help you perform your duties. The line division is a division within the maintenance department. Figure 5-1 shows how the line division fits within the maintenance department. The aircraft maintenance officer is the department Figure 5-1.—Navy O-level maintenance department organization. 5-1

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