CHAPTER 6. MAINTENANCE SCHEDULE
6-1. THE MAINTENANCE SCHEDULE. Title 14 CFR part 119, § 119.49 and part 121, § 121.135(b) require you to have maintenance time limitations, also called a maintenance schedule. These same rules permit you to use standards for determining your maintena nc e time limita t io ns, which are the regulatory basis of FAA-approved reliability programs. The maintenance time limitatio ns set out the what, how, and when of your scheduled maintenance effort. Although in the past the schedule includ ed only basic overhaul limits and other general requirements, today it includes a specific list of each individual maintenance task and its associated interval. The regulations are broad enough to permit you to organize all of these individual tasks into a series of integrated scheduled work packages of your own design that provide a continuous succession of necessary or desirable scheduled maintenance tasks for your entire airplane.
NOTE: You should not confuse the meaning of the terms “instructions for continued airworthiness” (ICA), required by 14 CFR part 25, § 25.1529, “time limitations” (maintenance schedule), required by § 121.135(b)(18), and “airworthiness limitations” (AL) required by part 25, appendix H, § H25.4.
Although related, each term has a significant meaning within the context of the stated part and section of the regulation.
6-2. THE FAA’s ROLE IN RELATION TO THE MAINTENANCE SCHEDULE. The FAA authorizes your maintenance schedule through your operations specifications (OpSpecs), and your Continuing Analysis and Surveillance System (CASS) monitors that schedule to verify its effectiveness (i.e., producing the desired results). Your CASS will be your principal source of informatio n that might indicate a needed change to your maintenance schedule. (We describe the CASS in Chapter 11 and in much more detail in the current edition of AC 120-79, Developing and Impleme nt i ng an Air Carrier Continuing Analysis and Surveillance System.) We expect you to correct any deficiencies in your maintenance schedule. Under § 121.373(b) and 14 CFR part 135, § 135.431(b), if you do not make needed changes, we can require you to change your maintenance schedule or any other element of your maintenance program found deficient.
6-3. MAINTENANCE SCHEDULE CONTENTS.
a. Maintenance Schedule Should Contain the Following Information:
(1) What (Unique Identifier). This is the item that you are going to maintain. Your identifier should be specific enough to allow the individ ual that you assign to do the scheduled maintenance task to easily and accurately identify the item. The following are examples of items that an operator’s maintenance schedule may include:
• Airworthiness Directives (AD),
• Service Bulletins (SB)/Service Letters (SL),
• Replacement of life-limited items,
• Replacement of components for periodic overhaul or repair,
• Special inspections,
• Checks or tests, Par 6-1 Page 19
• Lubricatio n and servicing,
• Tasks identified in the Maintenance Review Board Report (MRBR),
• ALs,
• Certification Maintenance Requirements (CMR),
• Supplement a l Structural Inspection Documents (SSID), and
• Electrical wiring interconnection system (EWIS).
(2) How (Task). This is how you should maintain the item you are going to maintain, or the scheduled maintenance task you will perform. A scheduled maintenance task is a maintenance action that you perform at regular, scheduled intervals. The intent of this task is to ensure the item can continue to perform its intended functio n, allows you to discover a hidden failure, or to ensure that a hidden function is available. You should not use terms such as “hard-time (HT),” “on-condit io n,” or “conditio n monitored” in your maintenance schedule. The maintenance schedule should state the maintenance task to be performed to meet the requirement
(e.g., Replace, Inspect, and Test).
(3) When (Timing). You should accomplish scheduled maintenance tasks (one-time or repetitive) at an acceptable time in service. You may measure time in service in calendar-time, operational hours, flight cycles, or any other appropriate parameter.
b. Maintenance Schedule Objective. Your overall maintenance schedule objective is to do the correct tasks at the correct interval. Keep in mind that more maintenance is not always a good idea, so if you decide to decrease intervals or add tasks, you should go through the same justification process as any other change to the maintenance schedule.
c. Maintenance Schedule Best Pr actice. For task management, invento ry, and audit purposes, you should identify on the maintenance schedule the task or work card associated with each scheduled maintenance task. This way you can ensure that you accomplish all of your scheduled maintenance tasks according to your schedule.
6-4. STANDARDS FOR DETERMINING MAINTENANCE SCHEDULES. As we mentioned in paragraph 6-1, §§ 119.49 and 121.135 permit you to have standards for determining your maintena nc e time limita t io ns. In the past, we used this language as the regulatory basis for FAA-approved reliability programs that evolved during the 1960s. These programs were based on the Air Transport Association of America’s (ATA) now obsolete process-based Maintenance Steering Group—2nd Task Force (MSG-2) decision logic that focused on failure rates and maintaining individual parts of the aircraft. Consistent with the continuo us evolutio n of aviatio n, MSG–2 became obsolete in 1980 with the advent of the ATA’s task-based Maintenance Steering Group—3rd Task Force (MSG-3) decision logic. MSG-3 focused on aircraft systems and a loss of functio n rather than on an individ ua l part failure. In any case, the management of these MSG-2 process-based programs was actuarial analysis.
Air carriers used the failure rates of a part to determine, through a probability process, the likelihood that the part would have a similar failure rate in the future. The standard was the acceptable failure rate. Air carriers used a failure rate alert program with upper control limits (UCL) and lower control limits (LCL) to track part failure rates. The air carrier was obliged to take action only when the failure rate deviated from the probability-based prediction Par 6-3 Page 20
(i.e., exceeded the UCL or the LCL). If the part did not respond, the air carrier had authorizatio n to move the UCL or LCL to make the failure rate fall within the alert program limit s.
a. Reliability Center ed Maintenance (RCM). During the 1970s, after collecting a large amount of operational data over time, the industry came to the realization that using failure rates and alert programs was not the most effective way of managing scheduled maintenance. Using the vast amount of operational data that was available, United Airlines, Inc. (UAL) developed and published a report during 1978 under a U.S. Department of Defense (DOD) contract entitled “Reliability Centered Maintenance (RCM).” This very significant document’s conclusio ns determined the flaws of the previous focus on part failure rate. RCM focused on the loss of function of an aircraft system. RCM determined that everything does not fail the same way;
failures occur according to six different failure patterns. RCM also determined that everything does not require the same type of maintenance; there are four different types of scheduled maintenance. RCM also took into account the different consequences (safety, operational, and economic) of a loss of functio n, as well as system functio nal redundancy and inherent design safety, when determining if scheduled maintenance was required. In some cases, RCM determined that no scheduled maintenance was required. This resulted in doing only required maintenance and a much lower maintenance burden.
b. MSG–3 Decision Logic. The RCM document was the major basis for the ATA’s development of the MSG-3 decision logic in 1980. Since then, most aircraft manufacturers have used the ATA’s MSG-3 decision logic to help them develop scheduled maintenance requirements for their new products. Besides providing organization and flow to the deliberative process, the primary attribute of the MSG-3 process is that the user can develop initial scheduled maintenance requirements without the operational data that is required to determine the need for scheduled maintenance tasks. Using the techniques of the MSG-3 decision logic, it is fairly simple to decide what tasks are required to be included in an initial scheduled maintenance program. However, the MSG-3 decision logic does not contain task interval selection decision logic to help the user determine where to set the task intervals, or how to adjust them after service is init iated. Using the MSG-3 process, initial task intervals are set on the basis of knowledge of the design, and the best judgment of the MRBR working group members. As a result, validat io n of initial interval selections must occur when the aircraft begins service and starts generating the operational data that was not available when the initial intervals were set.
c. Effective Scheduled Maintenance. An inherent functio n of your CASS is to determine the effectiveness of your scheduled maintenance effort through operational data collection and analysis activity. You use this important functio n to determine the level of scheduled maintenance effectiveness and to make the changes necessary to achieve the standard of effectiveness that you have set. Effective means “it is producing the desired results.” Thus, from an operational standpoint, an indicator of effectiveness of your scheduled maintenance effort is the availability of your aircraft for flight operations. If your aircraft are unavailable for flight operations due to maintenance reasons, then your scheduled maintenance program may not be as effective as it should be. There may be other elements of your maintenance program besides the scheduled maintenance element that may be deficient as well, but your CASS procedures will identify the root cause, and help you identify and make the adjustments/changes necessary to achieve the level of flight operations availability (the result) that you have set.
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d. MRBR Changes. MRBR revisions are developed to address global in-service experience in addition to reflecting new design configurations and new rules. Therefore, when MRBR revisions occur, you should review them and determine if they necessitate a change in your maintenance schedule based on your particular needs, experience, and program’s goals and philosophy.
NOTE: A revision to the MRBR alone does not automatically constitute an approval basis for an air carrier to change its existing maintenance schedule.
e. Failure Effect Categories (FEC). While you may make changes to your maintenance schedule, it is important for you to consider the task FEC that arises from application of the MSG-3 logic used to develop the MRBR (since this helps identify the relative criticality of the task). You should not delete or change the scope of MSG-3 FECs 5 (Evident Safety) and 8 (Hidden Safety) tasks without the concurrence/approval of the FAA Maintenance Review Board (MRB) Chairman and the Original Equipment Manufacturer (OEM)/type certificate holder (TCH).
NOTE: To protect the identity and significance of a safety-related task, you should identify each task in your maintenance schedule that is a CMR, AL, or those with FECs 5 and 8.
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CHAPTER 7. REQUIRED INSPECTION ITEMS
7-1. R equired Inspection Items (RII).
a. Tasks as RIIs. Title 14 CFR part 121, § 121.369(b) and part 135, § 135.427(b) require you to designate certain tasks as RIIs. Your RIIs must include at least those tasks that could result in a failure, malfunction, or defect that endangers the safe operation of the aircraft if the task is not completed properly or if you use improper parts or material. If other persons perform maintenance tasks for you, you may authorize them to accomplish your RII requirement, provided that your manual satisfies the regulatory requirements, as outlined in paragraph 7-2.
Consistent with the regulatio ns, you remain primarily responsible for the performance of each RII accomplished by the other person. When another person performs RII to include the entire aircraft, this is considered Essential Maintenance.
NOTE: See Chapter 9 for more information on Essential Maintenance .
b. Making RII Lists. Your RII lists should identify specific items of maintenance for each aircraft type you operate. It is inappropriate to designate entire systems as RIIs. You should adhere to a decision process, similar to the following, when creating a list of RIIs:
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FIGURE 7-1. REQUIRED INSPECTION ITEMS Required Inspection Item (RII)
Is a required test performed on the item that will simulate operational functions and defect failures, malfunctions or defects that would impact the safe flight or landing of the aircraft?
No No Yes Identify a task that that could result in a failure, malfunction, or defect endangering the safe operation of the aircraft, if not performed properly or if improper parts or materials are used Yes Yes No Designate task as a Required Inspection Item RII does not apply as system operational integrity can be assessed.
RII does not apply as those lists contain items of equipment which the Administrator has determined may be inoperative or removed while still maintaining aircraft airworthiness RII does not apply as it is limited to installations and repairs on aircraft Is the item potentially deferrable per the minimum equipment list (MEL) or Configuration Deviation List (CDL)?
Is work being performed on the Aircraft?
Yes Par 7-1 Page 24
c. RIIs and Safety. RIIs relate directly to flight safety. Consider all your RIIs with the same safety of flight consideration and emphasis even if accomplis hing an individ ua l RII adversely impacts your flight schedule, it is related to a scheduled or an unscheduled task, or it arises at an awkward time or at an inconvenient location.
7-2. RII PROCEDURES, STANDARDS, AND LIMITS.
a. List of Other Persons. Your manual must includ e a list of persons with whom you have arranged for the performance of any required inspections (§§ 121.369(a) and 135.427(a)), both within your organizatio n and within other organizatio ns that perform maintenance on your behalf. This listing must include a designatio n by occupational title of the personnel authorized to perform each required inspection (§§ 121.369(b)(3) and 135.427(b)(3)).
b. Certification. With consideration of the exception at §§ 121.378(a) and 135.435(a), each individ ua l that you grant an RII authorizatio n to must hold an appropriate airman’s certifica te. This is an air carrier qualification requirement; the individual does not exercise that certificate when accomplishing the RII. You must formally notify each of these individ ua ls of their RII authorization as well as its scope (§§ 121.371(d) and 135.429(e)).
c. RII Requirements. You should clearly identify your RII requirements on work forms, job cards, engineering orders, etc., or by any other method consistent with your maintenance program. A primary concept of the RII functio n is to prevent any person who performs any item of work from performing any required inspection of that work (§§ 121.369(b)(7) and 135.427(b)(7)). Therefore, it is important that you identify RIIs whenever possible so that everyone knows that an RII is required. You should also clearly state RII buy-back procedures (§§ 121.369(b)(4) and 135.427(b)(4)).
d. Standards and Limitations. You must set procedures, standards, and limits necessary for required inspectio ns, and acceptance or rejection of the RII (§§ 121.369(b)(5) and 135.427(b)(5)). You should have those procedures, standards, and limits necessary for the accomplishment of your required inspections. You must also have those procedures, standards, and limits necessary for the acceptance or rejection of each of your RIIs. As you will not find RIIs or procedures, standards, and limits for RIIs in an Original Equipment Manufacturer (OEM) manual, you will have to develop these and put them in your manual. Your manual must specify the method of performing required inspections (§§ 121.369(b)(3) and 135.427(b)(3)).
e. Proce dure s. Your manual must include procedures to ensure that you perform and complete all required inspections (§§ 121.369(b)(6) and 135.427(b)(6)) before you release the aircraft to service (§§ 121.369(b)(9) and 135.427(b)(9)).
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CHAPTER 8. MAINTENANCE RECORDKEEPING SYSTEM
8-1. REASONS FOR MAKING AND KEEPING MAINTENANCE RECORDS. Your primary reason to make and retain air carrier maintenance records is to show that the U.S. standard airworthiness certificate on your aircraft is effective and that your aircraft is Airworthy. A U.S. standard airworthiness certificate is effective only as long as the maintenance and alterations are performed according to the requirements of the FAA’s regulations. If your required aircraft maintenance records are incomplete or inaccurate, it can render your aircraft’s U.S. standard airworthiness certificate ineffective. Maintenance actions, in almost all cases, become intangible or abstract after the fact. Therefore, in order for you to make a maintenance action tangible, you must make a record of that maintenance action. Additionally, making a record of certain summary informatio n supports identificatio n of the current inspectio n and airworthiness status of your aircraft.
8-2. PART 43 REQUIREMENTS. You can find the basic requirement to make a maintenance record in 14 CFR part 43, § 43.9(a); however, § 43.9(b) indicates that the governing requirements for you, an air carrier, are found in 14 CFR part 121 or 135. That is another way of saying that the recordkeeping requirements of § 43.9(a) do not apply to you. However, the requireme nt s of § 43.9(b) are consistent with the air carrier maintenance recordkeeping requireme nt s of part 121, §§ 121.369(c) and 121.380(a) and (c), or part 135, §§ 135.427(c) and
135.439.
8-3. WORK PERFORMED BY A PART 145 CERTIFICATED REPAIR STATION (CRS).
a. Retaining Records. Title 14 CFR part 145, § 145.219 sets forth requirements for a CRS to retain certain records of maintenance that it performs. It also requires the repair station to make those records available to the FAA. However, these §§ 43.9(a) and 145.219 requirements do not apply when the repair station is accomplis hing any work on your aircraft.
b. Copies of Records. The wording of the § 145.205 regulations, as well as 14 CFR part 119, § 119.1(c), and §§ 121.1(b), and 135.1(a)(2), compel a part 145 CRS to follow the procedures and requirements of your maintenance program and applicable sections of your maintenance manual when accomplishing any maintenance or alterations on your aircraft.
Consequently, a CRS must use the performance standards of part 121 or 135, including the recordkeeping requirements, instead of following the provisions in part 145 and the repair station’s Repair Station Manual (RSM). This is consistent with the requirements of the Paperwork Reduction Act, which does not permit the government to require two separate but identical sets of records. The responsibility for retaining records in accordance with the retention requirements of §§ 121.380(c) and 135.439(b) rests with you, the air carrier, not the repair station. However, if a part 145 repair station wants to retain a copy of those records generated by working on your aircraft, our regulatio ns do not preclude them from doing so. Asking the part 145 repair station to keep your records for you is consistent with regulatio ns, although you are responsible for retaining them and making them available to the FAA. This is consistent with the requirements of § 119.59(c).
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8-4. AIR CARRIER MAINTENANCE RECORDKEEPING.
a. Maintenance Records are Important For:
(1) The air carrier, in fulfilling its responsibility to determine, validate, and maintain the airworthiness status of its aircraft; and
(2) The FAA, for use during a continuing review of aircraft maintenance records as a direct means of determining the airworthiness and safety status of air carrier aircraft.
b. Review ing Maintenance Recor ds. Because reviewing maintenance records is often the only direct means of determining the accomplishment of required maintenance, Federal law treats the act of intentionally failing to make and keep, as well as the act of intentionally falsifying, mutilating, or altering air carrier aircraft records, as a criminal act subject to the imposit io n of substantia l fines and/or impriso nme nt.
8-5. MAKING AND KEEPING REQUIRED RECORDS.
a. Recor dkeeping System . FAA regulatio ns (§ 121.369(c) or § 135.427(c)) require you to have and use a recordkeeping system for the preservation and retrieval of all work performed on your aircraft. You must document your system in your maintenance manual. The primary objectives of these systems are the generation, storage, retention, and retrieval of accurate and complete air carrier aircraft maintenance records. As stated earlier, these records are primarily made to show that the U.S. standard airworthiness certificate of your air carrier aircraft is effective, and that your aircraft is Airworthy and capable of safe flight.
b. Record Locations. FAA regulatio ns (§ 119.59(b)(1)(ii)) also require you to make and keep a listing that identifies the location of each record, document, and report that you are required to make and keep, as well as a listing that identifies each person that is responsible for each of those records, documents, and reports.
c. Airworthine ss Dire ctive s (AD). FAA regulatio ns (§§ 121.380(a)(2)(vii) and
135.439(a)(2)(v)) also require you to keep a record of the current status of applicable ADs, includ ing the date and methods of compliance, and, if the AD involves recurring action, the time and date when the next action is required.
8-6. REQUIRED AIR CARRIER MAINTENANCE RECORDS. Current requirements found in §§ 121.380 and 135.439 call for two types of records: a list of current status infor mat io n, and air carrier airworthiness release form records.
8-7. WHEN TO MAKE RECORDS AVAILABLE TO THE FAA. Section 119.59(c) mandates that you must make your air carrier maintenance records available to us. We can require you to make your records available to us at any time.
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8-8. RESPONSIBILITY FOR MAKING RECORDS AVAILABLE TO THE FAA.
Under § 119.59(b)(1), you must make a list of persons in your organization that you have designated to be responsible for making each required maintenance record, document, or report available to the FAA upon request. You must make a list of the location of each record, document, or report. You must keep this list current and make it available to the FAA at your principal base of operations.
8-9. REQUIRED RECORDS. You are required to make and keep certain current status records. Current status recordkeeping requirements are listed in §§ 121.380 and 135.439 and explained as follows :
a. Total Time in Service. The total time in service of the airframe, each installed engine, and each installed propeller is a record that contains the time in service accrued since new or rebuilt, expressed in hours, landings, or cycles.
NOTE: It is important for you to know that “rebuilt” does not have the same meaning as “overhauled” (§ 43.2(b)).
b. Current Status of Each Life-Limited Part. The current status of each life-limited part of each airframe, engine, propeller, and appliance means a record that contains at least the following information:
(1) Time in service since new, expressed in the appropriate parameter (e.g., hours, cycles, calendar-time);
(2) The time in service remaining to the specified life limit expressed in the appropriate parameter (e.g., hours, cycles, calendar-time);
(3) The specified life limit expressed in the appropriate parameter (e.g., hours, cycles, calendar-time); and
(4) A record of any action that alters the part’s life limit or changes the parameter of the life limit.
NOTE: If you conduct operations under part 135, total time in service and the current status of life-limited parts also includes rotors.
c. Time Since Last Overhaul. The listing of the time since last overhaul means a record that contains at least the following information:
(1) An identification of the item that requires overhaul and its associated scheduled overhaul interval;
(2) The time in service since the last overhaul was accomplished;
(3) The time in service remaining until the next scheduled overhaul is due; and
(4) The time in service when the next scheduled overhaul is due.
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