AC 120-16F

Historical

Advisory circular · Air Carrier Maintenance Programs

A newer version is currentThis is a historical version. AC 120-16G is the version in force, approved January 4, 2016.
Approved
November 15, 2012
Last reviewed
August 6, 2024
Cancelled by
AC120-16G
Family
AC 120-16 · 6 versions
Revision
F
14 CFR parts
1, 121, 135

Guidance, not mandatory unless a rule or AD requires it. DRS record last changed November 22, 2025.

Show pages 27–38

Par 8-10 Page 33

(3) Consistent with §§ 121.709(d) and 135.443(d), you may include a statement in your manual that the signature in the aircraft log of an authorized, appropriately certificated individual constitutes an approval for RTS under your air carrier maintenance program. Such an authorized signature constitutes the four air carrier approval for RTS certifications without restating each one of the certifications. You must prepare your Airworthiness Release Form or log entry in accordance with procedures in your manual and must include the following four certifications consistent with statutory considerations for operations with the highest degree of safety in the public interest.

(a) The work was performed in accordance with the requirements of your manual;

(b) All items required to be inspected were inspected by an authorized person who determined the work was satisfactorily completed;

(c) No known condition exists that would make the aircraft unairworthy; and

(d) So far as the work performed is concerned, the aircraft is in condition for safe operation.

(4) The Airworthiness Release Form or log entry must be signed by an appropriately certificated individual who is authorized by you to make the Airworthiness Release Form or log entry on your behalf.

NOTE: The Airworthiness Release Form or log entry must be accomplished by an authorized mechanic or repairman on your behalf under your part 121 or 135 certificate authorizations. This is consistent with the requirements and authorizations of § 43.7(e), § 121.379(b), or § 135.437(b), and § 121.709(b)(3) or § 135.443(b)(3).

NOTE: Consistent with regulations, no individual may issue an Airworthiness Release Form or make a maintenance log entry unless you have authorized them.

NOTE: Because a part 145 repair station is not an individual, these same regulations preclude accomplishment of your Airworthiness Release Form or log entry by a part 145 CRS. With one exception, the Airworthiness Release Form or log entry must be executed by an authorized, certificated individual as described in § 121.709 or § 135.443 and according to your procedures. The authorized individual may be employed by the repair station, but they are acting on your behalf, not on behalf of the repair station. This is consistent with §§ 119.1(c) and 121.1(b) or § 135.1(a)(2).

(5) Your maintenance manual should include detailed procedures for accomplishing the Airworthiness Release Form or log entry after you accomplish any maintenance on your aircraft.

Your procedures should include processes designed to ensure that you do not operate your aircraft after any maintenance, preventive maintenance, or alteration is accomplished, unless you complete the Airworthiness Release Form or maintenance log entry.

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(6) Your maintenance manual should include detailed procedures for qualifying and authorizing each individual that you use to accomplish your § 121.709 or § 135.443 Airworthiness Release Form or log entry. These procedures should include a positive, readily available means for you to document and transmit the authorization to the individual, including the scope and limitations of their authorization.

c. Service Difficulty Reports (SDR). You are required to make SDRs by §§ 121.703 and 135.415. While analysis of these reports can help your CASS identify deficiencies within your maintenance program, these reports are also our primary means of gathering information for our Service Difficulty Reporting Subsystem (SDRS).

d. Mechanical Interruption Reports. We require you, under §§ 121.705 and 135.417, to make mechanical interruption reports. These reports document those instances when there is an interruption to one of your flights, unscheduled change of aircraft en route, or unscheduled stop or diversion from a route caused by known or suspected mechanical difficulties that are not required to be reported under the SDR reporting requirements of § 121.703. You are also required to report the number of engines that you removed prematurely because of malfunction, failure, or defect, listed by make, model, and the aircraft type in which it was installed. If you operate aircraft with propellers, you must report the number of propeller featherings in flight, listed by type of propeller, and engine and aircraft on which it was installed. You do not need to report propeller featherings for training, demonstration, or flight check purposes. This is a prime indicator of deficiencies in the effectiveness of your maintenance program. Moreover, Root Cause Analysis (RCA) of these events is one of your most useful means of oversight of the level of effectiveness of your maintenance program.

8-11. REQUIREMENTS FOR REPORTS OF MAJOR ALTERATIONS AND MAJOR REPAIRS.

a. Part 121 Major Repair and Major Alteration Reports. If you conduct operations under part 121, § 121.707 requires you to make a report of each major alteration and major repair. You must submit the major alteration report to us, and you must make the major repair report available to us for inspection. This falls under § 119.59 requirements. In addition, because you are an air carrier, you do not have to use FAA Form 337, Major Repair and Alteration (Airframe, Powerplant, Propeller, or Appliance), to report a major alteration or major repair that you or a maintenance provider accomplished.

b. Part 135 Major Repair and Major Alteration Reports. If you conduct operations under part 135, there is no requirement that requires you to submit reports of major alterations or major repairs. However, while a report is not required, the records of aircraft maintenance or alteration are required and you must make them available to us when we ask for them.

NOTE: You should not confuse these alteration and repair reports with the current status listing of major alterations required under part 121 or the current status listing of major repairs and alterations required under part 135.

Par 8-12 Page 35 (and 36)

8-12. REQUIREMENTS FOR HISTORICAL OR SOURCE RECORDS. You do not have to keep historical or source records to prove that your required records, such as current status records, that you must make, keep, and make available to the FAA, are true and accurate.

Inherent with the requirements and objectives of your air carrier maintenance program, you must have a system to prepare, store, and retain your required maintenance records; you must monitor that system under your CASS to ensure that you are following your procedures and that they are effective. This ensures that your required records are true and accurate. Records such as the in-service history of life-limited parts (traceability back to birth) or the record of accomplishment of an AD do not need to be kept indefinitely. However, remember there are severe criminal penalties for falsifying or failing to make or keep air carrier records. Consistent with FAA regulations, unless there is evidence to the contrary, an aircraft maintenance record produced by your maintenance recordkeeping system should be acceptable by itself, without other historical or source records. The important consideration here is that you have a sound and properly working recordkeeping system. You may wish to archive certain source documentation records that you used to introduce parts or components into your maintenance system. These records may include documents such as the manufacturer’s invoice for new parts, export certificates of airworthiness, documentation of a major repair or alteration, or other similar information that may be useful in the future. You may also have business reasons to maintain historical records.

But you can keep historical records of your own choice, not because there are regulatory requirements that require you to keep various historical records. The only records that we can legally require to you to make, retain, and produce for our review are those records that we have clearly outlined in 14 CFR.

Par 9-1 Page 37 CHAPTER 9. CONTRACT MAINTENANCE

9-1. MAINTENANCE PROVIDERS. As a result of confusion related to the meaning of various terms such as contract maintenance, outsource maintenance, outsource contract maintenance, outsource maintenance provider (OMP), and substantial maintenance, we have standardized all these terms to two terms in this AC.

• When we say “contract maintenance,” we mean any maintenance, preventive maintenance, or alterations accomplished by an air carrier maintenance provider.

However, you always retain primary responsibility for any contract maintenance accomplished by your air carrier maintenance providers.

• When we say “air carrier maintenance provider” or “maintenance provider,” we mean any person with whom you, an air carrier, have made arrangements for the accomplishment of any of your maintenance, preventive maintenance, or alterations.

a. Essential Maintenance. Essential maintenance encompasses any RII on wing accomplished after any maintenance or alteration. This maintenance, if done improperly or if improper parts or materials were used, would result in a failure effect that would endanger the continued safe flight and landing of the airplane. Essential maintenance is the accomplishment of the air carrier designated inspection item on wing. Essential maintenance does not encompass any off-wing maintenance.

b. Maintenance Provider List. Under our maintenance manual rules, we require you to list each person who accomplishes contract maintenance for you in your manual. In this listing, we also require you to identify each of your maintenance providers by name, location, and a general description of the work. We recommend that you identify the description of work for your maintenance providers using the following five categories. If you operate more than one type of aircraft, the categories should include the type of aircraft. For categories four and five, you should include the type of specialized service or the kind of component, as appropriate.

These lists are used for your CASS functions and should have that level of detail needed by your maintenance provider surveillance and audit planning functions.

(1) Aircraft maintenance;

(a) Heavy maintenance.

(b) Line maintenance.

(2) Aircraft engine work;

(3) Propeller work;

(4) Component work; and

(5) Specialized service.

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c. Essential Maintenance Provider List. For your essential maintenance providers, you should have a means to identify, within your list, those maintenance providers who accomplish essential maintenance for you. You should also identify the specific required inspection that you have authorized each essential maintenance provider to accomplish for you in your maintenance provider list.

9-2. RESPONSIBILITY FOR MAINTENANCE PERFORMED BY OTHERS. Consistent with §§ 121.1(b), 135.1(a)(2), and others, when you use a maintenance provider to accomplish all or part of the maintenance activities on your airplane or its component parts, that maintenance provider becomes part of your maintenance organization and under your control. However, §§ 121.363 and 135.413 make it clear that you remain primarily responsible for all of the maintenance performed by that maintenance provider on your aircraft. You must determine that the maintenance provider has the capability to do your work on your behalf, direct their work, and determine that their work was done satisfactorily according to your manual and your standards. Because all work on your aircraft must be performed in accordance with your maintenance manual and your maintenance program, you must also provide the maintenance provider with appropriate material from your maintenance manual for that work. You must ensure that the maintenance provider follows the procedures in your manual that you have provided (refer to subparagraph 3-2c). You should accomplish this through work-in-progress audits while the maintenance provider is actually accomplishing the work. Your manual system should accommodate work performed for you by each maintenance provider. The policy and procedures portion of your maintenance manual should assign clear authority and responsibilities and outline procedures for your personnel to administer, control, and direct all contract maintenance. You should arrange the technical material that you provide for the use and guidance of the maintenance provider. When possible, you should have a written contract with anyone performing contract maintenance for you on a continuing basis. This will help ensure that your responsibilities are addressed. In the case of major operations, such as engine, propeller, or airframe overhaul, the contract should include a specification for the work. You should include or reference that specification in your manual system.

9-3. UNSCHEDULED CONTRACT MAINTENANCE PERFORMED AWAY FROM REGULAR FACILITIES. Sometimes, you will need maintenance performed on your aircraft while it is away from your regular maintenance facilities. You also may need maintenance services on short notice. Your maintenance manual should include procedures for obtaining these services under these unanticipated conditions. You should never use the term “emergency maintenance” to describe short notice unscheduled maintenance, as such terms imply to your employees and your maintenance providers that the FAA’s regulations and your procedures do not have to be followed. Emergency means that a serious situation has occurred unexpectedly, involves a peril to life or property, and demands immediate action. An out-of-commission aircraft parked on an airport ramp could hardly constitute a peril to life or property. You should outline the procedural steps that you will take to control and direct the unscheduled maintenance accomplished by your maintenance provider. Unscheduled, short notice requirements for maintenance do not void your responsibility to determine that your maintenance provider has the organization, adequate facilities and equipment, competent personnel, and appropriate portions of your manual for the work that needs to be done. These determinations must be made before any maintenance provider starts to work on your aircraft. These procedures and method of determination should be in your manual.

Par 9-4 Page 39

9-4. AIRWORTHINESS RELEASE FORM OR AIRCRAFT LOG ENTRY.

Sections 121.379(b) and 135.437(b) authorize you to approve your aircraft, airframes, aircraft engines, propellers, or appliances for RTS after you accomplish any maintenance, preventive maintenance, and alterations. These sections do not authorize any person other than you to approve your aircraft for RTS. Sections 121.709(b) and 135.443(b) outline requirements for those personnel making a log entry or issuing an air carrier Airworthiness Release Form under part 121 or 135 on your behalf. These regulations require a certificated repairman or certificated mechanic that you authorize to make the log entry or issue the Airworthiness Release Form for you. These regulations clearly do not authorize a repair station certificated under part 145 or any other entity to make an Airworthiness Release Form or log entry on your behalf. The regulations set forth clear personnel qualification requirements for each individual you so authorize. The approval for RTS authority remains solely with you. An individual may not issue an approval for RTS for your aircraft unless you authorize them to do so.

a. Log Entry or Airworthiness Release Form. You must designate each individual authorized to execute the log entry or Airworthiness Release Form for you by name and occupational title. The individual making the log entry or Airworthiness Release Form acts as your authorized agent. He or she certifies that the maintenance was accomplished according to your maintenance manual and maintenance program procedures and that no known condition exists that would make the aircraft unairworthy. This arrangement does not reduce the responsibility of maintenance personnel to accomplish maintenance functions or tasks in accordance with your manual.

b. Procedures for Log Entry or Airworthiness Release Form. Consistent with §§ 121.709(b)(1) and 135.443(b)(1), you must include in your maintenance manual the procedures for making an aircraft Airworthiness Release Form or log entry. Our regulations require you to make a log entry or complete an Airworthiness Release Form before you can operate your aircraft for any reason after you have accomplished any maintenance. You are required to make a log entry or an Airworthiness Release Form. Other than form or format, there is no legal or technical difference between an Airworthiness Release Form and a log entry.

9-5. EVALUATING NEW MAINTENANCE PROVIDERS. Before you can use a maintenance provider for the first time, you must determine that the maintenance provider candidate complies with pertinent requirements of part 121 subpart L or part 135 subpart J. In most cases, you would conduct an onsite audit. You must demonstrate, through this audit or by some other means, that the maintenance provider has an adequate organization, adequate facilities and equipment, competent personnel, and is capable of performing the work consistent with the requirements of your program. You should use a risk assessment process to determine whether to accomplish an onsite audit or not. Your risk assessment should take into account what happens (the failure effect) when the aircraft part or aircraft system that the maintenance provider works on fails. If the failure effect is safety, your procedures should mandate an initial onsite audit along with recurrent onsite audits, as well as the posting of a resident employee at the maintenance provider’s facility, who is assigned audit and oversight duties.

Page 40 Par 9-5 NOTE: Since the failure effect of parts and systems that come under essential maintenance is safety, we expect you to have robust policies and procedures to qualify, supervise, and control these maintenance providers, which should include onsite audits.

9-6. CONTINUING MAINTENANCE PROVIDER OVERSIGHT. Ensuring that each one of your maintenance providers is in continuous compliance is a major function of your CASS.

You should use your risk-based process for establishing a schedule for auditing and inspecting each of your maintenance providers. Inherent with a risk-based process, you may determine that some of your maintenance providers do not require an onsite audit. Consistent with the “performance” wording of § 121.373 or § 135.431, the audits that you accomplish should be primarily work-in-progress audits that serve to determine that your maintenance providers are following your manual. The audits should be accomplished by trained auditors, and the results analyzed by trained analysts. The results of the analysis should permit you to determine each maintenance provider’s continuing compliance with part 121 subpart L or part 135 subpart J, as appropriate, and your maintenance program.

9-7. USING A CRS AS ONE OF YOUR MAINTENANCE PROVIDERS.

a. Arrangements for Maintenance. If you decide to exercise your authority under § 121.379 or § 135.437 to make arrangements with other persons to accomplish contract maintenance for you as provided in your manual, you may choose to make these arrangements with an FAA CRS, but these rules do not require you to do so. The scope of your authorization to make arrangements for maintenance is very broad; you can make arrangements for maintenance with any person as that term is defined in § 1.1 as long as that maintenance provider accomplishes your maintenance in accordance with your manual and maintenance program.

Although the § 1.1 term “person” includes a CRS, it also includes anyone who does not hold an FAA certification.

b. Part 145 Maintenance Provider. The air carrier regulatory and maintenance program requirements that you would use to qualify a maintenance provider that holds a current part 145 repair station certificate are exactly the same as those that you would use for a maintenance provider who does not hold a current part 145 repair station certificate; there is no difference.

Consistent with § 119.1(c), § 121.1(b), or § 135(b)(1), each person, whether certificated or not, that is employed or used by you for any maintenance, preventative maintenance, or alteration of your aircraft is required to comply with the part 121 requirements and your maintenance program requirements, not part 65 or 145 requirements (refer to paragraph 8-3). Further, your § 121.379(b) or § 135.437(b) authorization to approve your aircraft for RTS after maintenance extends to the work accomplished under your § 121.379(a) or § 135.437(a) authorization to make arrangements with other persons for maintenance.

Par 10-1 Page 41 CHAPTER 10. PERSONNEL TRAINING

10-1. MAINTENANCE PROGRAM TRAINING REQUIREMENTS. You can find your specific air carrier maintenance training requirements in certain sections of part 121 subpart L and part 135 subpart J. Sections 121.375 and 135.433 require you to have a training program that ensures each person (including inspection personnel) who determines the adequacy of work done for you is fully informed about procedures and techniques and new equipment in use and is competent to perform his or her duties. There is an additional implied training requirement in part 121 subpart L and part 135 subpart J based on your responsibility to provide competent personnel for the proper performance of your maintenance program. A training program is the logical means for ensuring that maintenance personnel are competent. FAA regulations allow you to develop a training program fitting your particular needs.

10-2. TYPES OF TRAINING. Some of the possible types of training in your training program are initial training, recurrent training, specialized training, competency-based training, and maintenance provider training. You should select the appropriate training for your personnel, including your maintenance provider personnel, which you should base on an assessment of training needs. This assessment is a reflection of the required knowledge, skills, and ability to properly accomplish a given task or function and the current capability of those who you would assign a particular task or function.

10-3. INITIAL TRAINING. You should provide initial training right after you hire an employee, or when your existing employees begin to work on new equipment or a new assignment. Your initial training program may include subjects such as employee indoctrination or orientation, maintenance department policies and procedures, maintenance recordkeeping and documentation, aircraft systems or ground equipment, specific skills (for example, avionics, composite repair, aircraft run-up and taxi), skills upgrade, human factors, task-specific training, hazmat, or Environmental Protection Agency (EPA) and Occupational Safety and Health Administration (OSHA) regulations familiarization. Your initial training should also include a competence-based assessment of employees. This evaluates an employee’s previous training and experience and helps identify his or her specific individual training needs. The objective is to provide training that addresses the gap between required competence and the competence an individual already has.

10-4. RECURRENT TRAINING. Recurrent training is education occurring on a repetitive basis. You must provide maintenance personnel with the information and skills necessary to maintain your standard of competence. This training also accommodates the introduction of new aircraft; aircraft modifications; new or different ground equipment; new procedures, techniques, and methods; or other new information. Your recurrent training, although occurring on a repetitive basis, may not adhere to a defined schedule. You should not provide repetitive information in recurrent training unless it is needed to maintain the desired degree of competence. Your recurrent training may include:

• Continuing competency training designed to maintain regulatory and certificate currency requirements.

• Refresher training on a seldom-accomplished task or seldom-used skill.

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• Update training for particular tasks or skills. Update training can include training bulletins, bulletinboard items, self-study tasks, and computer-based instruction (CBI).

• Any other continuing education or training that may not be provided on a defined schedule.

10-5. SPECIALIZED TRAINING. Your specialized training should focus on competence in specific tasks or areas of responsibility, such as RII, borescope, nondestructive testing, or flight control rigging. You might provide this training with initial or recurrent training. You do not need to limit it to maintenance subjects, but instead may include management skills training for new supervisors, computer skills, or other training necessary because of a change in an individual’s duties and responsibilities.

10-6. MAINTENANCE PROVIDER TRAINING. Your training program must provide appropriate information to each employee of a maintenance provider about your specific program. The training should include function-specific training appropriate to each person’s job assignment or area of responsibility. You do not need to provide training to maintenance provider personnel in areas that do not concern them. For example, training on aircraft log procedures and minimum equipment list (MEL) procedures would not be required for aircraft interior cleaners, but would be required for maintenance personnel assigned to oncall maintenance for you.

NOTE: If your maintenance provider has specific types of training for its personnel, you do not need to duplicate that training for those individuals.

However, you must ensure your maintenance provider actually has provided the training and that the training meets your own needs and training standards. This could be a CASS work-in-progress audit.

10-7. COMPETENCY-BASED TRAINING. Although air carriers historically have provided a specified number of maintenance training hours to ensure employees have the competencies needed for their jobs, studies have shown that it may be better for you to train to a competency-based standard. You do not have to perform this type of training on a defined schedule or for a specific number of hours. Rather, you should test each individual to evaluate what training he or she needs, and then use these evaluations to identify those personnel who retain a high level of subject competence and who may not require a particular block of instruction. Conversely, you also should identify those individuals who require more training.

Training to competence permits you to tailor training programs to the specific requirements of your individual maintenance personnel and maintenance providers.

a. When to Require Competency-Based Training. You could use competency-based training to raise an employee’s level of competence to that level required by the individual’s duties and responsibilities. You should have procedures to determine when an individual requires competency-based training. You may determine the need for this type of training through pre- or post-employment testing, or through the analysis and corrective action functions of your CASS.

If you use competency-based training, it should specifically address the lack of competence. In some instances, competency-based training may consist of an appropriately knowledgeable person simply reviewing procedures with an employee through on-the-job training (OJT). You should design competency-based training to fix an immediate knowledge or skill deficiency and

Par 10-7 Page 43 (and 44) the training may focus on one individual or a small group. You may include competency-based training in your initial or recurrent training requirements.

b. Competency Deficiencies. For those circumstances where you identify a competency deficiency through investigation of an event, your competency-based training should show an individual what happened, why it happened, and demonstrate, in a positive manner, how to prevent it from happening again.

c. Competency Improvement Training. You should orient your competency improvement training toward correcting personnel competence deficiencies that you have identified through your CASS.