U.
S. Department of Transportation Federal Aviation Administration Advisory Circular Subject: Guide for Developing a Receiving Inspection System for Aircraft Parts and Materials Date: 7/3/24 AC No: 20-154A Initiated by: AFS-300 Change:
1 PURPOSE OF THIS ADVISORY CIRCULAR (AC). This AC provides guidance and information for developing a receiving inspection system and for incorporation into a person’s existing receiving inspection system to help prevent the introduction of unairworthy articles into inventories. The aim is to establish sufficient traceability to determine that the article(s) were manufactured under Title 14 of the Code of Federal Regulations (14 CFR) part 21, were previously determined to be airworthy under 14 CFR part 43, and were produced to established industry or U.S. Government standards or accepted foreign standards. Like all AC material, this AC is not mandatory and does not constitute a regulation. It provides guidance and outlines a method of compliance with 14 CFR. This is one means, but not the only means, for developing a receiving inspection system. In lieu of following the method(s) prescribed herein, the applicant may elect to follow an alternate acceptable method that achieves the intended results. The contents of this document do not have the force and effect of law and are not meant to bind the public in any way, and the document is intended only to provide information to the public regarding existing requirements under the law or agency policies.
2 AUDIENCE. This AC applies to any person who has an existing receiving inspection system for aircraft parts and materials or who is interested in developing a receiving inspection system.
3 WHERE YOU CAN FIND THIS AC. You can find this AC on the Federal Aviation Administration’s (FAA) website at https://www.faa.gov/regulations_policies/advisory_cir culars and the Dynamic Regulatory System (DRS) at https://drs.faa.gov.
4 WHAT THIS AC CANCELS. AC 20-154, Guide for Developing a Receiving Inspection System for Aircraft Parts and Material, dated December 12, 2005, is canceled.
5 REGULATIONS, GUIDANCE, AND DEFINITIONS. Related regulations, guidance materials, and definitions are listed in Appendix C.
6 BACKGROUND. The FAA has expressed ongoing concern that unairworthy products and articles, as well as materials, are being installed on type-certificated products.
Therefore, the FAA recommends that parts installers, maintainers, manufacturers, and suppliers establish an enhanced receiving inspection system to help eliminate the safety risk posed by unairworthy components, parts, or materials. A comprehensive network of regulatory controls governs the design, manufacture, installation, and maintenance of aircraft parts. However, whether by inadvertent or deliberate action, products and articles
2 have been reported that do not meet regulatory requirements and are not eligible for installation. Maintenance providers should have a procedure describing their processes for procuring, receiving, and inspecting aircraft components, parts, and materials. These procedures will ensure conformity to the type design or specifications to ensure that the product being returned to service conforms to specified airworthiness requirements and is in a condition for safe operation.
7 DEVELOPING THE RECEIVING INSPECTION SYSTEM PLAN. This recommended receiving inspection system plan is intended to help prevent the entry of unairworthy and/or ineligible parts into inventories and therefore preclude their subsequent installation. The plan describing a receiving inspection system should be detailed to the extent that it meets all its objectives and expectations to ensure identification and traceability. A person should consider the scope of their operation’s complexity for the development of and enhancing their receiving inspection system. The system should be commensurate with the privileges and limitations of the operation.
Appendix A contains a suggested receiving inspection system checklist derived from the contents in this AC, and Appendix B provides a sa mple documentation matrix for making a document requirement determination based on the supplier of the part. Departments within the organization, such as purchasing, auditing, maintenance, etc., should be made aware of the enhanced receiving inspection requirements through training or other documented procedural means. The following paragraphs contain suggested minimum elements that should be considered for incorporation into the written receiving inspection system plan.
Note: Appendices A and B provide a comprehensive overview of the material presented in the body of this AC. Users should modify the checklists (Appendix A) and the sample supplier documentation matrix (Appendix B) to meet the needs of their specific organization. Additionally, AC 00-56, Voluntary Industry Distributor Accreditation Program, appendix 1, contains a documentation matrix based on the class of the part being evaluated.
7.1 Responsible Person(s). The responsible person should ensure that all incoming materials such as standard parts, components, or parts thereof, articles, equipment, and materials are acceptable for use on type-certificated products. In addition, the responsible person(s) should be identified in the plan and given authority for ensuring continuing quality control for all functions of the receiving and inspection written procedures and established standards.
7.2 Internal Quality Audit. Used to evaluate ongoing conformity with the receiving inspection system. Persons performing the quality audit as part of the evaluation program may be employed by, or an agent to, the organization. The objective of the internal quality audit process is to evaluate the effectiveness of the receiving inspection system by ensuring that it continues to follow the organization’s procedures and meet regulatory requirements. AC 145-5, Repair Station Internal Evaluation Programs, c ontains information on how to design and implement an Internal Evaluation Program (IEP).
7.3 Training. Training of all receiving inspection personnel is to ensure personnel have a thorough understanding of the receiving inspection system. The training syllabus should include, as a minimum, recognition in article identification, determining the current status of the article, conformance determination of the article, regulatory compliance requirements, inspection procedures, handling, storage, ordering procedures, bench or functional testing, and recordkeeping requirements. All training should be documented and personnel training records established and maintained during the period of employment. Recurrent training should be implemented for familiarization of practices and any changes to procedures, regulations, or policies.
7.4 Technical Data. Ensure currency, applicability, and adequacy for making proper evaluations. A procedure should be established to ensure that technical data is current in accordance with the regulations or manufacturer’s recommendations. This includes, but is not limited to, data such as:
1. Type Certificate Data Sheets (TCDS);
2. Airworthiness Directives (AD);
3. U.S. or industry specifications;
4. Illustrated parts lists or catalogs;
5. Maintenance and/or overhaul manuals;
6. Structural Repair Manuals (SRM);
7. Service Bulletins (SB)/Service Letters (SL), or other manufacturer’s technical information;
8. Parts markings;
9. Engineering drawings;
10. Maintenance records/return to service;
11. Other applicable data for making an airworthiness determination, etc.;
12. Federal aviation regulations; and
13. AC guidance.
7.5 Measurement/Test Equipment. Precision measurement devices, test equipment, and gauges used to verify conformance to the applicable regulations of 14 CFR part 43, § 43.13 and part 145, § 145.109(b), industry standards, and specifications must be calibrated in accordance with an effective program to maintain accuracy to the standards of the National Institute of Standards and Technology (NIST), manufacturer’s specifications, or the standards of another country that is comparable to NIST.
Calibration records should be maintained, showing established intervals for calibration for each precision measuring device and procedures for taking actions on deficiencies.
This would include having a recall system to prevent inadvertent use of uncalibrated equipment.
7.6 Written Receiving Inspection Procedures. Developing a receiving inspection system can be a difficult task, considering the numerous forms and the complexities of the various manufacturers’, repair facilities’, and parts suppliers’ (distributors’) paperwork involved, along with the end user/customer requirements. Written procedures for the receiving and inspection of incoming articles should be developed according to the individual organizations’ complexity and regulatory requirements. As an example, the written procedures could include the following items:
7.6.1 Establish minimum training requirements for receiving inspection personnel. The training curriculum should be based on the complexity of the organization’s needs.
7.6.2 To help minimize confusion, distributors (sellers of parts) should be requested to fill all blank entries with “NA” to signify that the blank box or section is not applicable. The purchasing department should convey its document requirements to all distributors in order to create a smoother flow of articles into inventories.
7.6.3 A checklist should be created for receiving inspectors that would clearly identify the origin and/or traceability “path” of the article. This would help reduce confusion and aid accountability within the receiving inspection department.
7.6.4 A method to identify whether the articles were obtained from the primary or secondary vendor. Primary and secondary vendors are determined by the purchaser on the vendor’s compliance with the organization’s needs and performance for supplying the appropriate articles. At times, it may be feasible to review the required documents before purchase of the item via electronic means.
7.6.5 Means should be created to recognize when parts are to be substituted or substitution parts may be used. The substituted parts should be reflected in the articles’ maintenance records and include substantiating equivalency approval data. The installer is responsible for determining that the substitute part meets all regulatory requirements.
7.6.6 A method should be developed with instructions explaining how to perform comprehensive visual inspections of articles received, including checks for obvious physical damage, defects, and state of preservation, and that appropriate quantities have been received.
7.6.7 A means to verify that all part, model, serial numbers, etc., as appropriate, match the accompanying documentation, such as packing slips, invoices, certificates of conformance, work orders, maintenance release tags, or purchase orders.
7.6.8 To ensure articles are free from contamination or damage, verify that all appropriate plugs, caps, or safety devices are installed as required by the manufacturer and that the shipping container or packing is appropriate for items received or to be shipped.
7.6.9 If applicable, a method should be created to identify dangerous goods that are flammable, toxic, or volatile materials received to ensure that they are packaged and stored in a safe manner, either per manufacturer’s recommendations or as specified by regulatory requirements. Segregation procedures should be established for these types of materials and for any other items for which segregation is appropriate.
7.6.10 When applicable, a method should be included to examine materials subject to damage from electrostatic discharge (ESD). Materials should be packaged, handled, and protected in accordance with requirements for handling ESDs. Training for ESD recognition, handling, and processing should be accomplished and records maintained in the receiving inspection training file or the individual employee’s training file. In addition, procedures should be defined, prescribing periodic checks/inspections on ESD mats and wrist straps in accordance with the manufacturer’s recommendations.
7.6.11 Procedures explaining how to segregate and identify serviceable parts from unserviceable parts and maintaining documentation for traceability. The storage area for serviceable aircraft parts should be periodically checked (audited) for overall effectiveness of storage and identification methods of parts in inventory. The serviceable parts area should be controlled to prevent unintentional or unauthorized stocking of parts, materials, or components that have not been received through the system. Identified unserviceable (questionable) parts should be properly secured in a segregated area pending proper disposition of the part.
7.6.12 Develop a procedure to control bulk shipments of identical parts to ensure traceability to the producer of the item(s) (i.e., Production Approval Holder (PAH), standard parts, or raw material(s), etc.). Whenever possible, original packaging should remain with the parts or materials for identification purposes. This would be used for identifying the producer and lot or batch number as applicable, until installed or sold.
7.6.13 Develop a procedure to identify and properly store materials with a specified shelf life, life-limited articles, and environmentally sensitive/temperature-sensitive materials such as epoxy resins, prepreg composite materials, or sealants as an example. This procedure should ensure that outdated parts or materials are not inadvertently installed. Procedures should be in place to track the expiration date of and to explain how to segregate or dispose of them once their useful life has expired.
7.6.14 Establish a means to verify whether any ADs are applicable to any of the components or parts thereof received.
7.6.15 When inspection stamps are used, a control system should be established to govern their issuance and use.
7.6.16 Procedures to ensure incoming articles effectively apply to the products being maintained.
7.7 Hazardous Materials (HAZMAT) (Dangerous Goods Program). HAZMAT (known internationally as dangerous goods) are found in many aircraft parts and in substances used in the aviation industry. Because there have been instances in the past when companies have shipped HAZMAT in violation of the regulations, the regulations require HAZMAT training for certain employees. A company’s HAZMAT program should address the company’s needs for training, as well as its internal procedures for handling and transporting HAZMAT. The principal applicable regulations are found in Title 49 of the Code of Federal Regulations (49 CFR) parts 171, 172, 173, and 175, which prescribe requirements applicable to aircraft operators, maintenance providers, distributors, and anyone else who may ship HAZMAT. These regulations address a wide range of topics, such as developing a training program, properly identifying HAZMAT, packaging HAZMAT, shipping HAZMAT, and air carrier acceptance of HAZMAT. Additional regulatory guidance on training programs for certain types of certificate holders (CH) can be found in 14 CFR parts 121, 135, and 145. At a minimum, any HAZMAT e mployer should have a program that covers proper packaging, marking, labeling, classification, description, and documentation of shipments of HAZMAT, as well as compliance with the appropriate regulations that apply to the particular HAZMAT-related functions undertaken at the company.
Note: A dditional HAZMAT information is available on the FAA website at https://www.faa.gov/hazmat/safecargo. HAZMAT safety recommendations are available from the Department of Transportation’s (DOT) Pipeline and Hazardous Materials Safety Administration (PHMSA) website at https:/ / www.phmsa.dot.gov.
7.8 Article Documentation/Identification. Procedures should clearly state and/or illustrate the documentation or other means of identification that would be acceptable for receiving articles from different types of vendors. The following are possible sources, but not the only sources, for determining airworthiness:
7.8.1 Shipping ticket, invoice, or other documents from the PAH.
7.8.2 Parts markings such as Parts Manufacturer Approval (PMA), Technical Standard Order (TSO), data plates, serial numbers, part numbers, manufacturing production numbers, etc.
7.8.3 Letter of Direct Ship Authority, issued to the supplier by the PAH.
7.8.4 Maintenance release document(s) that meet part 43, signed by an appropriately certificated person, qualified for the relevant function, that signifies the item was approved for return to service after maintenance, preventative maintenance, rebuilding, or alteration. Records could also reflect the removal of articles from a type-certificated product.
7.8.5 FAA Form 8130-3, Authorized Release Certificate, Airworthiness Approval Tag, is used for export approval, conformity determination from the PAH, or approval for return to service after maintenance or alteration by an authorized part 145 repair station or the holder of an air carrier operating certificate issued under part 121 or 135.
7.8.6 Export Certificate of Airworthiness (C of A), Joint Aviation Authority (JAA) Form 1 (invalid if dated after 11/28/04), Transport Canada Authorized Release Certificate – Form One, and European Union Aviation Safety Agency (EASA) Form 1 (effective on 11/28/04) provided the United States has a current Bilateral Aviation Safety Agreement (BASA) and Maintenance Implementation Procedures (MIP) with the exporting country.
7.8.7 Other part or material certification forms, or a material certification form verifying that the standard parts conform to established industry or U.S. specifications, could be provided.
7.9 Part Evaluation. The evaluation should include a review of any usage history supplied with the part at the time of purchase, which could include accumulated time/cycles, remaining time/cycles, alterations, and/or repairs. Part verification could also include part number, serial number, symbols, manufacturing marks, identification stamps, etchings, casting codes, barcodes, dates, or lot numbers. Any item (indicators such as manufacturing numbers) unique to a particular manufacturer could assist in providing traceability to a PAH. The manufacturer’s system for identification during the manufacturing process is not always available to the end user. However, such information is often obtained by contacting the manufacturer.
7.10 Unsalvageable Articles. Establish written procedures for disposing of scrap products and materials. When appropriate, the proper and thorough mutilation of products and articles will ensure they are unusable for their original application and render them incapable of being reworked or camouflaged to provide the appearance of being serviceable. When mutilation is not appropriate, other methods may be used to prevent future representation such as those described in AC 21-43, Production Unde r 14 CFR Part 21, Subparts F, G, K, and O, Appendix D, Scrap or Salvageable Aircraft Products and Articles.
7.11 U nserviceable Parts. Parts that may have exceeded approved repair limits, time, cycle limits, etc. If unserviceable parts are to be retained for possible future use, procedures should specify that they are to be segregated from serviceable parts. It is recommended that all documentation remain with these parts for possible later return to service, which could be because new approved repair procedures were later developed or the manufacturer extended time life extensions.
7.12 Segregation. At times, articles received may lack appropriate documentation or other supporting data necessary to show that the regulatory requirements were met. These requirements would include findings to show that the part was produced and/or maintained properly. Segregate those parts of questionable nature from serviceable parts until a sound determination can be made of their status and prevent them from subsequently being installed.
8 RECEIVING INSPECTION PROCEDURES FOR PARTS AND MATERIALS TEMPLATE. The following receiving inspection procedures provide information and guidance for developing and/or evaluating a receiving inspection system. These procedures set forth one means, but not the only means, for receiving parts or materials into inventories.
8 Note: Appendices A and B provide a comprehensive overview of the material presented in the body of this AC. Users should modify the checklists (Appendix A) and the sample supplier documentation matrix (Appendix B) to meet the needs of their specific organization. Additionally, AC 00-56, appendix 1, contains a documentation matrix based on the class of the part being evaluated.
8.1 Acceptance of New Parts Manufactured by FAA-C ertificated Sources. Receiving personnel should ensure that new parts produced by FAA-certificated sources are accompanied by the referenced documents or other information:
8.1.1 Production Certifi cate (PC) Holders. Invoice, packing list, or equivalent documentation (normal shipping documents), stating the part number(s) and corresponding quantities in each shipment.
8.1.2 Supplemental Type Certificate (STC) H older. Normal shipping documents, documentation that identifies the part as an STC part and the production authority under which the part was produced.
8.1.3 Technical Standard Order Authorization (TSOA) Holder. Normal shipping documents, documentation, and/or markings that identify the part as a TSO part.
8.1.4 PMA Holder. Nor mal shipping documentation and/or markings that identify the part as an FAA-PMA part. The part or packaging must be marked “FAA-PMA” (refer to 14 CFR part 45, § 45.15).
8.1.5 Approved Production Inspection System (APIS) Holder. Normal shipping documents, other documentation, and/or data plates that identify the product as being produced under a type certificate (TC) only with an APIS.
8.1.6 Letter of Direct Ship Authority Authorization. E vidence that authority was given to the supplier from the PAH to ship parts directly to the customer, which may have a statement on the purchase order stating that the part(s) “were produced under FAA-approved manufacturing and quality control systems/methods as set forth in the FAA Production Certificate.”
8.2 Acceptance of New Parts from Non-F AA-Certificated Sources. Receiving personnel should ensure that the distributor (seller) provides sufficient documentation to show traceability to one of the following:
1. A copy of shipping tickets, packing lists, invoices, and/or other documents providing evidence that the origin of the part is from an FAA PAH or that the original acquisition was from an FAA-approved source.
2. A copy of the written letter of direct shipment authorization that includes a statement that those parts were produced in accordance with the PAH quality system.
3. A copy of the Certificate of Conformity (C of C) (i.e., standard parts). This certificate should identify the acceptable standard to which the part was produced.
4. A copy of the return to service from FAA-approved foreign repair stations and/or FAA-certificated sources.
5. The return to service entry under part 43 maintenance record entry.
6. A return to service record entry from an FAA-certificated air carrier operating under part 121 or 135.
8.3 Acceptance of Used, Repaired, or Overhauled Parts from FAA-Certificated Sources.
One or more of the following should accompany parts approved for return to service procured from FAA-certificated sources:
1. Repair station work order.
2. FAA Form 8130-3; JAA Form 1 (prior to 11/28/04); EASA Form 1 (after 11/28/04);
or Transport Canada Authorized Release Certificate – Form One.
3. Air carriers operating under part 121 or 135 return to service maintenance record entry.
4. Part 145 repair station return to service maintenance record entry that the repair station is authorized to perform.
5. Parts/components maintained under part 43 return to service release.
8.4 Acceptance of Used, Repaired, or Overhauled Parts from Non-FAA-Certificated Sources. Parts procured from non-FAA-certificated sources, such as distributors, should be accompanied by one of the following:
1. A return to service maintenance record entry from an FAA-certificated air carrier operating under part 121 or 135;
2. A return to service maintenance record entry from an FAA-certificated air agency operating under part 145;
3. The return to service entry from the certificated entity that performed the original repair or overhaul under part 43; or
4. For “as-is” articles, documentation that describes the current condition of the article and conveys that the part may not meet airworthiness requirements.
8.5 Acceptance of Parts from Foreign Sources. The need to maintain aircraft and components outside the United States has continued to expand, along with an increase in the rise of foreign-manufactured aeronautical products used by U.S. operators and repair facilities. Receiving personnel should ensure they receive the proper documents with parts that were repaired or manufactured from foreign sources.
8.6 Acceptance of Life-Limited or Time-Controlled Parts from Any Source. Procedures for accepting life-limited or time-controlled used parts into an inventory system require special attention due to safety ramifications. In addition to the documentation listed above, receiving inspection personnel should ensure that life-limited and time-controlled parts are accompanied by the following documentation:
8.6.1 Documentation that substantiates the part number, serial number, and current life status of the part (i.e., the accumulated total time or remaining hours, cycles, and/or calendar time, whichever time limit applies to the part; or any usage/storage history, which may result in an adjustment to the remaining life of the part).
Note: Life-limited parts, when sold or transferred, must include the mark, tag, or other record used to comply with § 43.10.
8.6.2 Optional additional documentation that can help to establish history and installation eligibility of the article:
1. AD status;
2. Modification status (i.e., SBs, technical bulletins), if applicable;
3. All major repairs, alterations, and modifications accomplished on the article; and
4. Record of work accomplished during the last maintenance, repair, overhaul, or alteration performed.
9 SUSPECTED UNAPPROVED PARTS (SUP). SUP reports originate from many different sources, such as being detected during incoming receiving inspections, facility audits or surveillance, complaints, congressional inquiries, or from accident or incident investigations. The FAA’s policy is to encourage voluntary disclosure of information affecting aviation safety, such as SUPs. Although reports may be made anonymously, the submission of the reporter’s name is requested to enable the FAA to gather additional information if needed and provide confirmation and/or followup to the reporter.
AC 21-29, Detecting and Reporting Suspected Unapproved Parts, provides updated information and guidance to the aviation community for detecting SUPs and the procedures for reporting them to the FAA. FAA Form 8120-11, Suspected Unapproved Parts Report, serves as a standardized means of reporting. Additional information and guidance can be found at the following:
1. SUP Program Office web site at https://www.faa.gov/aircraft/safety/programs/sups.
2. Federal Aviation Administration Office of Audit and Evaluation 800 Independence Avenue, SW Washington, DC 20591 Attn: AAE-300, Room 911
3. FAA Aviation Safety Hotline at 800-255-1111.
4. Questions or comments regarding a SUP-related issue may also be directed to the SUP Program Office via https://www.faa.gov/aircraft/safety/programs/sups.
9.1 SUPs Procedures. Organizations should incorporate SUPs identification, reporting, and disposition procedures into the receiving inspection system. Procedures should also include a system for reviewing inventory and suppliers when SUP reports have been issued by the FAA.
9.2 SUPs Training. Organizations should develop and provide training to employees, appropriate to their duties, on the detection of SUPs and on the organizations’ procedures for identifying, reporting, and dispositioning a SUP.
10 AC FEEDBACK FORM. For your convenience, the AC Feedback Form is the last page of this AC. Note any deficiencies found, clarifications needed, or suggested improvements regarding the contents of this AC on the Feedback Form.
H ugh Thomas for Lawrence Fields Executive Director, Flight Standards Service
Appendix A A-1 APPENDIX A. RECEIVING INSPECTION SYSTEM CHECKLIST
RECEIVING INSPECTION SYSTEM CHECKLIST
RESPONSIBLE PERSON
Y N N/A
1. [ ] [ ] [ ] Receiving inspection personnel listed on company roster by position and name?
2. [ ] [ ] [ ] Inspection functions authorized for named individual identified?
3. [ ] [ ] [ ] Individual trained to perform authorized functions, by name?
4. [ ] [ ] [ ] Individual issued a letter or stamp for functions authorized to perform?
TRAINING
Y N N/A
1. [ ] [ ] [ ] Individuals’ training records documented?
2. [ ] [ ] [ ] Training records on file and subject(s) covered?
3. [ ] [ ] [ ] Part/material identification procedures?
4. [ ] [ ] [ ] Procedures for identifying current status of part/material?
5. [ ] [ ] [ ] Procedures for making a quality determination of the part/material?
6. [ ] [ ] [ ] Understand regulatory compliance requirements?
7. [ ] [ ] [ ] Inspection procedures for individual’s intended function?
8. [ ] [ ] [ ] Proper handling procedures?
9. [ ] [ ] [ ] Proper storage procedures?
10. [ ] [ ] [ ] Ordering procedures?
11. [ ] [ ] [ ] Functional testing procedures?
12. [ ] [ ] [ ] Inspection procedures (i.e., visual, bench check, etc.) for airworthiness determinations?
13. [ ] [ ] [ ] Recordkeeping requirements?
14. [ ] [ ] [ ] Use of inspection stamps and control procedures?
15. [ ] [ ] [ ] Hazardous materials (HAZMAT) procedures?
TECHNICAL DATA
Y N N/A
1. [ ] [ ] [ ] Current?
2. [ ] [ ] [ ] Applicable?
3. [ ] [ ] [ ] Adequate?
4. [ ] [ ] [ ] Production Approval Holder (PAH) design data?
5. [ ] [ ] [ ] Type Certificate Data Sheets (TCDS)?
6. [ ] [ ] [ ] Airworthiness Directives (AD)?
7. [ ] [ ] [ ] U.S. or industry specifications?
8. [ ] [ ] [ ] Illustrated parts lists or catalogs?
9. [ ] [ ] [ ] Maintenance manuals?
10. [ ] [ ] [ ] Structural Repair Manuals (SRM)?
11. [ ] [ ] [ ] Overhaul manuals?
12. [ ] [ ] [ ] Service Bulletins (SB)/Service Letters (SL)?
13. [ ] [ ] [ ] Operator’s Federal Aviation Administration (FAA)-approved maintenance program/requirements?
14. [ ] [ ] [ ] Manufacturer’s specifications?
15. [ ] [ ] [ ] Code of Federal Regulations (CFR)?