AC 120-16E

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
September 11, 2008
Last reviewed
August 6, 2024
Cancels
AC120-16D
Cancelled by
AC120-16E CHG 1
Family
AC 120-16 · 6 versions
Revision
E
14 CFR parts
119, 121, 135, 1, 91, 43

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

Show pages 27–38

Par 904 Page 35 (and 36) provider’s continuing compliance with part 121, subpart L, or part 135, subpart J, as appropriate, and your maintenance program.

905. USING A CERTIFICATED REPAIR STATION AS ONE OF YOUR MAINTENANCE PROVIDERS.

a. If you decide to exercise your authority under §§ 121.379 or 135.437 to make arrangements with other persons to perform maintenance, preventive maintenance, and alterations for you as provided in your manual, you may choose to make these arrangements with an FAA certificated repair station, but you are not required to do so. The scope of your authorization to make arrangements for maintenance is very broad; you can make these arrangements for maintenance with any “person” as that term is defined at 14 CFR § 1.1.

Although the 14 CFR § 1.1 term “person” includes a certificated repair station, it also clearly does not exclude any other “person” who does not hold an FAA certification.

b. 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 part 145 requirements.

c. Further, your §§ 121.379(b) or 135.437(b) authorization to approve your aircraft for return to service 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 1000 Page 37 CHAPTER 10. PERSONNEL TRAINING 1000. 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 maintenance personnel are competent. FAA regulations allow you to develop a training program fitting your particular needs.

1001. 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 is based 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 would be assigned the task or function.

1002. INITIAL TRAINING. You should provide initial training right after a person is hired, or when your personnel 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, hazardous materials, or Environmental Protection Agency and Occupational Safety and Health Administration 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.

1003. 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:

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

b. Refresher training on a seldom accomplished task or seldom used skill.

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c. Update training for particular tasks or skills. Update training can include training bulletins, bulletin-board items, self-study tasks, and computer-based instruction.

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

1004. SPECIALIZED TRAINING. Your specialized training should focus on competence in specific tasks or areas of responsibility, such as RII, borescope, non-destructive 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.

1005. 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 procedures would not be required for aircraft interior cleaners, but would be required for maintenance personnel assigned to on-call 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.

1006. 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 competencybased 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. Competency-based training can be used 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. You should design competency-based training to fix an

Par 1006 Page 39 (and 40) immediate knowledge or skill deficiency and 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. 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. Your competency improvement training should be oriented toward correcting personnel competence deficiencies that may be identified through your CASS.

Par 1100 Page 41 CHAPTER 11. CONTINUING ANALYSIS AND SURVEILLANCE SYSTEM (CASS) 1100. BACKGROUND OF THE CASS. Introduction of the CASS requirement resulted from an FAA-industry study of a series of maintenance-related air carrier accidents occurring during the 1950s. The study found that, in many cases, the primary causal factor of an accident was a fundamental weakness or weaknesses in the maintenance program. The study found that in some cases maintenance personnel failed to accomplish required maintenance tasks or failed to accomplish the task correctly. They simply didn’t follow the manual. In other cases, the study found that the maintenance program, even when followed as planned and documented, was not effective in preventing the situation that led to the accident. It did not produce the desired results.

a. Responding to this finding, the FAA introduced regulations (§§ 121.373 and 135.431) that require air carriers to establish and maintain a system for the continuing analysis and surveillance of the performance and effectiveness of their inspection, maintenance, preventive maintenance, and alterations programs.

b. These regulations further require that the air carrier’s CASS provide a process to correct any deficiency identified in those programs, regardless of whether the work was accomplished directly by the air carrier or by other persons.

1101. CASS IS A SAFETY MANAGEMENT TOOL. A CASS is your system for managing safety as it relates to maintenance functions. As a safety management tool, it is part of the overall structure of policies and procedures that you use to ensure operations are to the highest degree of safety. It is a structured, methodical process that helps you reach your maintenance program objectives. CASS is the only management system currently mandated by regulation. If you use it properly, your CASS becomes an inherent way of doing business for you, and helps you promote a culture of safety in your company by providing a formal process for employees to identify and correct safety discrepancies. As you will see in the following brief discussion of the structure of a CASS, the same objectives of measuring and continuously improving the performance (program execution) and effectiveness (program results) of a major function (maintenance) apply equally to all safety-related functions that must be managed by an air carrier.

1102. BASIC CASS PROCESSES.

a. Your CASS is a risk-based, closed-loop system that has four basic processes:

(1) Surveillance. An information gathering/audit process you use to collect data to measure your program execution and measure your program results.

(2) Analysis. An analysis process you use to identify any maintenance program deficiencies and any necessary corrective actions.

(3) Corrective Action. A planning process you use to ensure that your corrective actions and implementation steps are well-defined.

(4) Followup. A followup, performance measurement process you use to verify that your corrective actions are performed and are effective. This is also an information-gathering and analysis process, thereby, closing the loop.

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b. During the first step, surveillance, you will gather and obtain data using an audit program to support measurement of performance (program execution). Your audit program should be well-structured, based on risk assessment, and accomplished by individuals trained and skilled specifically at auditing. Consistent with the wording of the regulation, your primary type of audit should be work-in-progress audits that evaluate if the worker is following the manual.

Your auditors would also look at areas such as manuals and other maintenance technical data, aircraft condition, actual in-process maintenance practices, training, publications, and ground operations. In addition, information gathering to obtain data that will support the measurement of effectiveness (program results) is generally a collection of flight operational data such as accidents/incidents, mechanical delays and cancellations, in-flight engine shutdowns, unscheduled landings, engine performance, pilot log book write-ups, and unconfirmed components or parts removals.

c. In the second step, you will analyze the data to identify indications of maintenance program weaknesses. Your analysis should be accomplished by individuals experienced and/or trained as analysts. One of your key objectives here is to not only identify a weakness, but to determine its root cause. This is where your knowledge of human factors becomes critical.

d. Based on the results of your analysis, the third step is for you to develop a corrective action, if necessary, again taking into account human factors so that your corrective action is likely to be successful. Once you determine what the corrective action is, you will develop and implement a corrective action plan.

e. To close the loop, the fourth step of your CASS will have you conduct a followup measurement process using surveillance and analysis to verify that your corrective action was implemented properly and completely and that it has effectively corrected the deficiency you identified. You can design this followup data gathering process specifically for the issue of interest, or you can make it a part of your continuing surveillance that is the first step of your CASS. Determining if a special information gathering is needed is part of your analysis that you accomplished in step three.

f. Note that both the initial and followup surveillance can and should have proactive and reactive aspects to them. In the case of audits, by auditing systems and procedures, as well as specific transactions, the analysis of audit results can identify weaknesses in a process.

Correcting these weaknesses before a problem results is a proactive approach. An audit also may uncover a missed or improper maintenance action. Investigating this finding and correcting the immediate problem is a reactive process. Developing and implementing a corrective action to prevent a similar future event is equally important for improving the maintenance program, and it is required by the regulations. Similarly, your analysis of operational performance data from a systems point of view can result in identification of a system’s weakness before a specific unwanted event, such as a cancellation, occurs, which is a proactive process. Investigating and correcting an undesirable operational event related to the maintenance program after it has occurred, though reactive, also is a necessary and desirable procedure.

1103. RISK-BASED DECISIONS. All effective CASS take into account the need to manage risk to an acceptable level, as well as the practical limitations that must be faced when addressing deficiencies. Consequently, you must set priorities and make choices for planning audits and

Par 1103 Page 43 other information gathering activities, analyzing data, and selecting and implementing corrective actions. You should tie setting such priorities directly to a risk assessment process, so the resulting maintenance program achieves its objectives.

1104. SCOPE OF CASS. CASS monitors all 10 elements of your maintenance program:

• Airworthiness responsibility,

• Air carrier maintenance manual,

• Air carrier maintenance organization,

• Accomplishment and approval of maintenance and alterations,

• Maintenance schedule,

• RII,

• Maintenance recordkeeping system,

• Contract maintenance,

• Personnel training, and

• CASS.

1105. CASS DESIGN PRINCIPLES.

a. The following are attributes of system safety:

(1) Clear authority,

(2) Clear responsibility,

(3) Specific written procedures,

(4) Effective controls,

(5) Performance measures, and

(6) Well-defined interfaces.

b. These six system safety attributes should be the starting point for the design of your CASS. It should be clear who in your organization is responsible for and who has authority over the CASS. You should not divide responsibility/ authority into two or more parts due to the likely possibility that activity such as auditing and operations data analysis are poorly coordinated. Typically, in addition to an individual with overall CASS responsibility, you should have a management board or committee to ensure good communications and coordination of all

Page 44 Par 1105 CASS functions and to maintain regular senior level management involvement. This oversight group also can provide a form of control over critical aspects of your CASS operation and measure the performance and effectiveness of the CASS itself.

c. In addition to the many elements within your maintenance organization, there are many interfaces between the CASS and functions or organizational elements of a typical air carrier that are outside maintenance. Some of the more obvious examples are engineering, flight operations, purchasing, safety, and the FAA. It also is important to ensure the CASS relationships to your other programs (if they exist) such as internal evaluation programs, Flight Operations Quality Assurance programs, voluntary disclosures, and Aviation Safety Action Programs, are welldefined and coordinated 1106. CASS PERSONNEL REQUIREMENTS.

a. An effective CASS requires certain skills that may not be readily available within a maintenance organization. For example, auditing skills are not automatically inherent in those skilled in maintenance. Analysis capability, particularly related to root cause determination, risk analysis, and consideration of human factors is specialized and generally requires specific training and experience.

b. For all operators, but particularly for the smaller ones, required personnel can be shared, functions can be performed part-time, and some functions can be accomplished under contract.

However, it is essential that you recognize the need for knowledge and skills that do not necessarily coincide with those resulting from many years of maintenance experience repairing airplanes.

NOTE: You can find more detailed information concerning developing and implementing a CASS in AC 120-79, Developing and Implementing a Continuing Analysis and Surveillance System.

Par 1200 Page 45 CHAPTER 12. ADMINISTRATIVE 1200. REGULATORY REFERENCES. The regulations that underlie this AC are found in 14 CFR. A summary of specific regulatory sections follows:

a. Scope of Regulatory Applicability, §§ 119.1(c), 121.1(b), 135.1(a)(2);

b. Air Carriers’ Responsibility for Airworthiness, and for Performing Maintenance, §§ 121.363 and 135.413;

c. Air Carrier Maintenance Programs, §§ 119.5, 119.49, 121.133, 121.367, or 135.21;

d. Maintenance Program Manual, §§ 121.133, 121.137, 121.367, 121.369, 135.21, and

135.427;

e. Maintenance Organization, §§ 119.65, 119.67, 119.69, 119.71, 121.365, and 135.423;

f. Maintenance Time Limitations, §§ 119.49, 121.135, and 135.23;

g. Performance and Approval of Maintenance and Alterations, §§ 119.1(c), 121.1(b),

121.379, 135.1(a)(2), and 135.437;

h. Performance and Approval of Maintenance and Alterations Performed by Other Persons, §§ 119.1(c), 121.1(b), 121.379, 135.1(a)(2), and 135.437;

i. Continuing Analysis and Surveillance System, §§ 121.373 and 135.431;

j. Personnel Training, §§ 121.367(c), 121.375 and 135.433;

k. Maintenance Recordkeeping and Reports, part 121, subpart V; §§ 121.369, 121.380;

135.415, 135.417, 135.427, and 135.439(b);

l. Maintenance Log, §§ 121.563, 121.701, 121.709, and 135.65;

m. Service Difficulty Reports, §§ 121.703 and 135.415;

n. Required Inspection Items, §§ 121.365, 121.369, 121.371, 135.427, and 135.429;

o. Mechanical Interruption Reports, 14 CFR §§ 121.705 and 135.417; and

p. Alteration and Repair Reports, §§ 43.9(b), 121.707, and 135.439(a)(2)(vi).

1201. OTHER RELATED LEGAL AND GUIDANCE MATERIAL. For more information, consult current editions:

a. 14 CFR parts 43, 91, 119, 121, and 135;

b. 49 U.S.C. § 46310, Reporting and Recordkeeping Violations;

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c. AC 120-79, Developing and Implementing a Continuing Analysis and Surveillance System;

d. FAA Order 8900.1, Flight Standards Information Management System (FSIMS);

e. Air Transport Association (ATA) MSG–3, Operator/Manufacturer Scheduled Maintenance Development; and

f. Report number AD-A066-579, Reliability-Centered Maintenance.

1202. OBTAINING REFERENCE MATERIAL.

a. You can get the CFRs and those ACs for which there is a fee from the Superintendent of Documents, U.S. Government Printing Office, Washington, DC 20402. You can access current regulations online at http://www.access.gpo.gov/ecfr/. You can access the United States Code online at http://www.gpoaccess.gov/uscode/index.html.

b. You can be placed on FAA’s mailing list for free ACs by contacting the U.S.

Department of Transportation, SVC-121.21, Washington, DC 20590.

c. You can request free ACs from the U.S. Department of Transportation Subsequent Distribution Office, SVC-121.23, Ardmore East Business Center, 3341 Q 75th Avenue, Landover, MD 20785.

d. You can request MSG–3 information from the Air Transport Association of America;

1301 Pennsylvania Ave., NW, Suite 1100, Washington, D.C. 20004. You can also contact ATA online at http://www.airlines.org/products/pubs/.

e. You can get Report Number AD-A066-579, Reliability-Centered Maintenance, from the U.S. Department of Commerce, National Technical Information Service, Springfield, VA, 22161. http://www.ntis.gov/ Sales Desk: 1-800-553-6847 or 703-605-6000, 8 a.m.-6 p.m.;

EST, Mon-Fri.