Par 403 Page 13 required inspections from the function of the other maintenance, preventive maintenance, and alteration activities. This organizational separation must be below the level of administrative control where overall responsibility for the required inspection functions as well as the other maintenance, preventive maintenance, and alteration functions is exercised. Consistent with paragraph 402(b) of this AC, your DOM exercises overall authority and responsibility over the required inspection functions, as well as the other maintenance (including inspection), preventive maintenance, and alteration functions. See Figure 4-1 for a representative organizational chart
Page 14 Par 403 FIGURE 4-1. TYPICAL ORGANIZATIONAL CHART SHOWING THE
ORGANIZATIONAL SEPARATION OF THE RII FUNCTION AND THE OTHER
MAINTENANCE, PREVENTIVE MAINTENANCE, AND ALTERATION FUNCTION
OVERALL AUTHORITY
AND RESPONSIBILTY
FOR BOTH RII AND
OTHER MAINTENANCE
AND ALTERATION
FUNCTIONS
PART 119 DIRECTOR
OF MAINTENANCE
DIRECT RESPONSIBILITY
FOR OTHER
MAINTENANCE AND
ALTERATION
FUNCTIONS
MANAGER OF
MAINTENANCE
DIRECT RESPONSIBILITY
FOR RII FUNCTIONS
PART 119 CHIEF
INSPECTOR
Par 500 Page 15 CHAPTER 5. ACCOMPLISHMENT AND APPROVAL OF MAINTENANCE AND
ALTERATIONS
500. ACCOMPLISHMENT OF MAINTENANCE.
a. As a maintenance entity, you are authorized under 14 CFR §§ 43.3(f), 43.7(e), 121.379, and 135.437 to perform maintenance on your own air carrier aircraft and to approve them for return to service without obtaining any other maintenance certification. In addition, §§ 121.379 and 135.437 provide clear authority for you, under your air carrier certificate, to perform maintenance on behalf of other air carriers who conduct operations under the same part as you do. You may also perform maintenance for an air carrier or other operator conducting operations under a different part than you are. However, this maintenance is not included in your air carrier maintenance authority; therefore, any maintenance that you perform under this circumstance must be separated and independent of your authority and certification as an air carrier.
b. Each individual who makes an airworthiness determination on your behalf must hold an appropriate airman’s certificate. Sections 121.378 and 135.435 require that any individual who you put directly in charge of performing maintenance hold an appropriate airman certificate, such as a mechanic certificate with ratings appropriate to the work being performed.
Section 121.371 requires that any individual that you authorize to perform RII for you hold an appropriate airman certificate. Section 121.709 requires that anyone who you authorize to issue an approval for return to service hold an appropriate airman’s certificate. Your DOM and chief inspector must hold an airman’s certificate with airframe and powerplant ratings. These certificate requirements are air carrier qualification requirements, not requirements for an airman certificate that are needed or exercised to do maintenance. All maintenance on your aircraft and approval for return to service is accomplished under your air carrier certificate by your maintenance organization or persons authorized by you, not by any individual or organization under their certificate. One exception to the individual airman certificate requirement occurs if you arrange for a certificated repair station located outside the United States to perform maintenance. At such repair stations, individuals directly in charge of performing maintenance or required inspections are not required to hold FAA airman certificates.
501. MAJOR REPAIRS AND ALTERATIONS. Under §§ 121.379(b) and 135.437(b), major repairs and alterations must be done in accordance with technical data approved by the FAA.
Appendix A to part 43 contains a list of repairs and alterations that are considered to be major.
However, you should note that the Civil Aeronautics Agency published a list of repairs and alterations to specific parts, as well as specific types of repairs that were considered major repairs during 1953. This major repair and alteration list was later adopted, unchanged, as part of appendix A of part 43. Exclusive reliance on the part 43, appendix A list of major repairs and alterations to make the major/minor classification will result in the classification of some minor repairs as major and classification of some major repairs as minor simply because the appendix A list has not been updated to include evolving airplane design and construction techniques such as composite structures and the high speed, high altitude pressurized jet transport that did not exist when the list was developed. You should have detailed major/minor classification procedures in your manual to evaluate each repair or alteration on a case-by-case basis using such factors as the certification basis of the aircraft, classification of the structure as primary,
Page 16 Par 501 secondary, or a primary structural element, or classification as a fail-safe, safe-life, or damagetolerant structure.
502. AIRWORTHINESS RELEASE FORM OR AIRCRAFT LOG ENTRY AND APPROVAL FOR RETURN TO SERVICE. After performing any maintenance on your airplane, you must approve it for return to service before you may operate it. As an air carrier, you must issue an approval for return to service under §§ 121.709 or 135.443 as appropriate.
You can read additional, more detailed information about approving your airplanes for return to service in chapter 8 of this AC.
503. SCOPE OF MAINTENANCE. You must provide instructions in your maintenance program and maintenance manual for maintenance and alterations encompassing the four areas of “what to do,” “when to do it,” how to do it,” and “was it done properly” in at least three major areas: scheduled maintenance, unscheduled maintenance, and specific maintenance requirements for major components of the aircraft.
a. Scheduled Maintenance. Scheduled maintenance consists of all the individual maintenance tasks performed according to the maintenance time limitations (maintenance schedule). Your scheduled maintenance activities should include procedural instructions for the maintenance tasks and requirements to record the results of the inspections, checks, tests, and other maintenance.
b. Unscheduled Maintenance.
(1) Unscheduled maintenance includes procedures, instructions, and standards for maintenance that occurs on an unscheduled or unforeseen basis. A need for unscheduled maintenance may result from scheduled maintenance tasks, pilot reports, or unforeseen events, such as high-load events, hard or overweight landings, tail strikes, ground damage, lightning strikes, or an engine over-temperature. In your maintenance manual, you should include instructions and standards for the accomplishment and recording of unscheduled maintenance and detailed procedures for recording all types of unscheduled maintenance.
(2) You should include a comprehensive process in the unscheduled maintenance portion of your manual that addresses those rare, very high-load events that occur to aircraft.
These very high load events may result in structural damage, but unless you have comprehensive procedures to identify and evaluate such damage, you may not identify this damage before you approve your aircraft for return to service. Your manual should include very high load event special inspection procedures that address at least these four objectives:
(a) Identify that a very high load event has/has not occurred,
(b) Assure that indications of structural damage are found in an initial inspection,
(c) Involve the OEM if necessary, and
(d) Provide a process for additional inspections that would identify all of the structural damage.
Par 503 Page 17 (and 18)
c. Specific Maintenance Requirements for Major Aircraft Components.
(1) Engine Maintenance Program. Your engine maintenance program should cover the maintenance of installed engines and off-wing engines for each engine model you operate. If your aircraft has auxiliary power units (APU), you may want to include APU maintenance as part of your engine maintenance program. Usually, the installed engine or APU requirements will be contained in the maintenance time limitations. In addition to procedural information, the off-wing program described in your maintenance manual should provide shop scheduling information or intervals for cleaning, adjusting, inspecting, testing, and lubricating each part of the engine or APU requiring that maintenance. You should include in your maintenance manual the degree of inspection, the applicable wear tolerances, and the work required when the engine or APU is in the shop.
(2) Propeller Maintenance Program. If applicable, your propeller maintenance program should cover the maintenance of installed propellers and off-wing propellers for each model you operate. Usually, the installed propeller system scheduled maintenance requirements will be contained in the maintenance time limitations. In addition to procedural information, the off-wing program described in your manual should provide shop scheduling information or intervals for cleaning, inspecting, adjusting, testing, and lubricating each part of the propeller system requiring that maintenance. You should include in your maintenance manual the degree of inspection, the applicable wear tolerances, and the work required at these periods. Some modern propellers are constructed of composite materials and, therefore, may require unique tools, repair procedures, and specialized training for your maintenance personnel.
504. PARTS AND APPLIANCES MAINTENANCE PROGRAM. For the most part, this component of your maintenance program covers shop operations, which may include both scheduled and unscheduled tasks. You may conduct these shop operations at some location other than where you perform maintenance on your aircraft. Your parts and appliance maintenance program should cover both installed parts and appliances and off-wing maintenance for each part and appliance model that you operate. Usually, the installed part and appliance scheduled maintenance requirements will be contained in the maintenance time limitations. In addition to procedural information, the off-wing program described in your maintenance manual should provide shop scheduling information or intervals for cleaning, adjusting, inspecting, testing, and lubricating each component of the part and appliance requiring that maintenance. Include in your maintenance manual the degree of inspection, the applicable wear tolerances, and the work required when the part or appliance is in the shop.
Par 600 Page 19 CHAPTER 6. MAINTENANCE SCHEDULE
600. THE MAINTENANCE SCHEDULE. Sections 119.49 and 121.135(b) require you to have maintenance time limitations, also called a maintenance schedule. These same rules permit you to make standards for determining your maintenance time limitations. This language is the regulatory basis of FAA-approved reliability programs that were developed in the 1960s. The maintenance time limitations set out the what, how, and when of your scheduled maintenance effort. Although in the past the schedule included only basic overhaul limits and other general requirements, today it includes a specific list of each individual maintenance task and its associated time limit. 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.
601. THE FAA’s ROLE IN RELATION TO THE MAINTENANCE SCHEDULE. The FAA authorizes your maintenance schedule through your OpSpecs, and your CASS monitors that schedule to verify its effectiveness, i.e., producing the desired results. Your CASS will be your principal source of information that might indicate a needed change to your maintenance schedule. (CASS is described in chapter 11 of this AC and in much more detail in AC 120-79.)
The FAA expects you to correct any deficiencies in your maintenance schedule. Under §§ 121.373(b) and 135.431(b), if you do not make needed changes, the FAA can require you to change your maintenance schedule or any other element of your maintenance program found deficient.
602. MAINTENANCE SCHEDULE CONTENTS.
a. Your maintenance schedule should contain at least 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 item to be easily and accurately identified by the individual assigned to do the scheduled maintenance task.
(2) How (Task). How to maintain the item; the scheduled maintenance task to be done.
A scheduled maintenance task is a maintenance action that you perform at regular, scheduled intervals so that you can ensure the item can continue to perform its intended function within its operating context, or so you can discover a hidden failure, or to ensure that a hidden function is available. You should not use terms such as hard time, on-condition, or condition monitored in your maintenance schedule. These terms represent obsolete 1960s methodology, are vague, and do not describe the maintenance task you are performing. If your maintenance schedule contains these terms, there is a risk that the scheduled maintenance you want and need may not be the maintenance that is being performed.
(3) When (Frequency). The time-in-service interval between the times when you accomplish a scheduled maintenance task. Your intervals are measured in time in service and may be measured by calendar time, operational hours, flight cycles, or any other appropriate parameter. In addition, for task management, inventory, and audit purposes, you should identify, on the maintenance schedule, the task or work card associated with each scheduled maintenance
Page 20 Par 602 task. This way, you can ensure that all of your scheduled maintenance tasks are being accomplished according to your schedule.
b. Your overall maintenance schedule objective is to correctly 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.
603. STANDARDS FOR DETERMINING MAINTENANCE TIME LIMITATIONS.
a. As we mentioned in paragraph 600 earlier, §§ 119.49 and 121.135 permit you to have standards for determining your maintenance time limitations. In the past, this language was used 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 continuous evolution of aviation, MSG–2 became obsolete in 1980 with the advent of ATA’s task-based Maintenance Steering Group – 3rd Task Force (MSG–3) decision logic. MSG–3 focused on aircraft systems and a loss of function rather than an individual 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, i.e., exceeded the UCL or the LCL. If the part did not respond, the air carrier was authorized to move the UCL or LCL to make the failure rate within the alert program limits.
b. 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 developed and published a report during 1978 under a U.S.
Department of Defense contract entitled “Reliability Centered Maintenance (RCM).” This very significant document was in stark contrast to the previous part failure rate focus. RCM focused on the loss of function of an aircraft system. RCM determined that everything doesn’t fail the same way; failures occur according to six different failure patterns. RCM also determined that everything doesn’t 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 function, as well as system functional 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.
c. 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 Air Transport Association’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
Par 603 Page 21 (and 22) 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 initiated. Using the MSG–3 process, initial task intervals are set on the basis of knowledge of the design, and the best judgment of the working group members. Under MSG–3, initial intervals are, essentially, a best guess. As a result, validation 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.
d. An inherent function of your CASS is to determine the effectiveness of your scheduled maintenance effort through operational data collection and analysis activity. You use this important function 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.
Par 700 Page 23 (and 24) CHAPTER 7. REQUIRED INSPECTION ITEMS
700. REQUIRED INSPECTION ITEMS.
a. Sections 121.369(b) and 135.427(b) require you to designate certain tasks as Required Inspection Items (RII). Your RIIs cover at least those maintenance tasks that, if not properly performed or if done with improper parts or materials, could result in a failure, malfunction, or defect that would endanger the continued safe flight and landing of your aircraft. In case maintenance tasks are performed for you by other persons, you may authorize them to accomplish your RII requirement. However, you must document the arrangement and control it through your maintenance manual. Consistent with the regulations, you remain primarily responsible for the performance of each RII accomplished by the other person.
b. RIIs relate directly to flight safety. Consider all your RIIs with the same safety of flight consideration and emphasis even if accomplishing an individual RII adversely impacts your flight schedule, or is related to a scheduled or an unscheduled task or arises at an awkward time or at an inconvenient location.
701. RII PROCEDURES, STANDARDS, AND LIMITS.
a. Your manual must include procedures for you to identify and authorize RII personnel, both within your organization and within other organizations that perform maintenance on your behalf (§§ 121.369(b)(3) and 135.427(b)(3)). Each individual that you grant an RII authorization to must hold an appropriate airman’s certificate. This is an air carrier qualification requirement;
the individual certificate is not exercised when accomplishing the RII. You must formally notify each of these individuals of their RII authorization as well as its scope (§§ 121.371(d) and
135.429(e)).
b. You should clearly identify your RII requirements on work forms, job cards, engineering orders, and the like, or by any other method consistent with your maintenance program. A primary concept of the RII function is that the person performing the item of work may not perform the required inspection on that item of work. Therefore, it is important that you identify RIIs whenever possible so that everyone knows that an RII is required.
c. You must 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 required inspection items. As you will not find required inspection items or procedures, standards, and limits for required inspection items in an OEM manual, you will have to develop these and put them in your manual.
d. You must have procedures in your manual to ensure that only a supervisor of an inspection unit or the person who has overall responsibility for both the RII function and other maintenance and alteration functions may countermand the decision of any RII inspector regarding an RII (§§ 121.369(b)(8) and 135.427(b)(8)). These requirements apply equally to an organization performing maintenance on your behalf, as well as your own maintenance organization. See Figure 4-1 for a representative organizational chart.