6-1 CHAPTER 6. MAINTENANCE SCHEDULE CHANGES—INTERNAL APPROVAL
AND IMPLEMENTATION
6.1 Approval Process. In addition to the appropriate substantiation data, the operator’s maintenance schedule adjustment process should define internal approval and implementation procedures. An approval plan should be comprised of procedures initiated by the competent review and disposition of a recommendation by the designated decision authority. The party responsible for the implementation of the change should be identified and defined. The operator should also develop methods to:
• Resolve nonconcurrence.
• Ensure closure of all proposals.
• Archive the disposition of a recommendation.
6.1.1 Revisions Without Direct FAA Involvement. Unless otherwise restricted (such as airworthiness limitations (AL), Certification Maintenance Requirements (CMR), electronic wiring interconnection system (EWIS), or Airworthiness Directives (AD)), you may make revisions to the maintenance schedule without direct FAA involvement.
However, you should coordinate significant revisions with the PMI prior to publishing your revision. Prior coordination with the PMI is recommended for all maintenance schedule revisions. You should be prepared to provide documentation to the FAA demonstrating that the process used to determine maintenance schedule revisions was accomplished in accordance with your standards for determining time limitations.
Note: Your entire process is subject to continual FAA oversight to verify you are executing your process in accordance with your program, and that your data-based decisions are in the interest of safety and program objectives.
Therefore, your program should include sufficient documentation and recordkeeping requirements.
6.2 Implementation. Your process should result in a comprehensive plan for implementing changes to the maintenance schedule. The plan should include procedures for notifying FAA representatives assigned to the air carrier that maintenance schedule changes are planned or have been made. The implementation plan should be documented and be included with other information considered during the change approval process. In most cases, any change to the maintenance schedule will require significant coordination with maintenance support organizations such as resource allocation, logistics, and planning groups, especially when the interval for an entire packaged check is revised.
6.2.1 Escalated Intervals and Task Deletions. These changes will normally become effective immediately upon attaining internal approval per the operator’s defined task amendment process. The implementation of individually escalated task intervals is relatively straightforward.
Note: Special considerations must be given to time/date check tasks that evaluate remaining life-limits. An in-service, life-limited item near its life-limit that passes
6-2 the task’s evaluation criteria at the original interval may end up exceeding its life-limit before the task is performed at the escalated interval. Prior to implementing the escalation, you must ensure there is sufficient time remaining on life-limited items at the new interval. A life-limited item may not remain in-service past the limit at which it becomes due.
6.2.2 De-Escalated Intervals. Based on the urgency of the reliability concern, the operator should determine when and how to implement the reduced interval. Options could range from:
• Waiting until the next scheduled completion of the task at the original interval,
• A phased-in schedule based on risk or other measure of exposure or desired outcome, or
• Immediate implementation of the reduced interval.
6.2.3 New Tasks. Similarly, the timing for implementation of new tasks should be based on the risk of the concern.
6.2.4 Followup. During implementation, the operator’s reliability program should continue to monitor the effectiveness of the overall maintenance schedule. Based on risk, an operator may need to follow up and report on specific changes or phases of implementation to confirm that the change does not adversely impact the affected system, and that the change is achieving the desired results.
7-1 CHAPTER 7. REPORTING AND DISPLAY FORMAT
7.1 General. All programs will require a means of displaying and reporting summaries of the collected data, analyses performed, and the status of internally approved recommendations.
7.1.1 Reporting. Reliability program reporting should:
1. Reflect the operator’s operational philosophy and economic goals regarding aircraft performance.
2. Develop one or more means of displaying and reporting collected data, including data displays summarizing the activity since the last reporting period.
3. Cover all aircraft systems controlled by the program in sufficient detail to enable recipients of the information to monitor the effectiveness of the maintenance schedule, including changes in maintenance and inspection intervals, and tasks.
4. Include enough data to accurately portray the carrier’s particular operation(s).
5. Be frequent enough to identify degrading trends before significant operational impact occurs.
6. Identify areas that have not achieved the established performance standards.
7. List continuing unfavorable performance or deficiencies carried forward from previous reports, and details of the progress of corrective actions taken.
8. Highlight implemented or planned recommendations.
9. Monitor the effectiveness of revisions to the maintenance schedule.
7.1.2 Methods and Frequency. Reliability reporting methods and frequency of reporting may vary by operator and will be dependent upon the complexity of operations.
7.1.3 Display. Operators may choose to incorporate all elements into a single report, or incorporate individual elements into multiple forms and forums, including electronic data displays, structured reports, and/or presentations.
7.1.4 Delivery. Your report distribution and timeline of delivery should be specified in your program, and should be provided to senior management representatives of the maintenance organization and your FAA office with oversight responsibility.
8-1 CHAPTER 8. ADMINISTRATIVE
8.1 Regulatory References. Refer to the following 14 CFR parts:
• Part 5.
• Part 91.
• Part 119.
• Part 121.
• Part 135.
8.2 Guidance References (current editions). Refer to the following ACs and orders:
1. AC 00-46, Aviation Safety Reporting Program.
2. AC 00-58, Voluntary Disclosure Reporting Program.
3. AC 20-136, Aircraft Electrical and Electronic System Lightning Protection.
4. AC 20-158, The Certification of Aircraft Electrical and Electronic Systems for Operation in the High-Intensity Radiated Fields (HIRF) Environment.
5. AC 25-19, Certification Maintenance Requirements.
6. AC 25-27, Development of Transport Category Airplane Electrical Wiring Interconnection Systems Instructions for Continued Airworthiness Using and Enhanced Zonal Analysis Procedure.
7. AC 26-1, Part 26, Continued Airworthiness and Safety Improvements.
8. AC 120-16, Air Carrier Maintenance Programs.
9. AC 120-42, Extended Operations (ETOPS and Polar Operations).
10. AC 120-59, Internal Evaluation Programs.
11. AC 120-66, Aviation Safety Action Program.
12. AC 120-72, Maintenance Human Factors Training.
13. AC 120-77, Performance Rules: Provisions Contained in an Operator Manual Under § 43.13(c).
14. AC 120-79, Developing and Implementing an Air Carrier Continuing Analysis and Surveillance System.
15. AC 120-92, Safety Management Systems for Aviation Service Providers.
16. AC 120-93, Damage Tolerance Inspections for Repairs and Alterations.
17. AC 120-94, Aircraft Electrical Wiring Interconnection Systems Training Program.
18. AC 120-97, Incorporation of Fuel Tank System Instructions for Continued Airworthiness into Operator Maintenance and/or Inspection Programs.
8-2
19. AC 120-98, Operator Information for Incorporating Fuel Tank Flammability Reduction Requirements into a Maintenance and/or Inspection Program.
20. AC 120-102, Incorporation of Electrical Wiring Interconnection Systems Instructions for Continued Airworthiness into an Operator’s Maintenance Program.
21. AC 120-113, Best Practices for Engine Time-In-Service Interval Extensions.
22. AC 121-22, Maintenance Review Boards, Maintenance Type Boards, and Original Equipment Manufacturer/Type Certificate Holder Recommended Maintenance Procedures.
23. AC 135-42, Extended Operations (ETOPS) and Operations in the North Polar Area.
24. FAA Order 8040.4, Safety Risk Management Policy.
25. FAA Order 8900.1, Volume 20, Chapter 5, Section 3, Reliability Programs:
Assessment, Acceptance, Authorization, and Surveillance.
8.3 Other Source References. Refer to A4A MSG-3, Operator/Manufacturer Scheduled Maintenance Development, current edition, available from:
Airlines for America (A4A) 1275 Pennsylvania Ave NW, Suite 1300 Washington, DC 20004 202-626-4000 https://www.airlines.org
8.4 AC Feedback Form. For your convenience, the AC Feedback Form is the last page of this AC. Note any deficiencies found, clarifications needed, or suggested improvements regarding the contents of this AC on the Feedback Form.
Appendix A APPENDIX A. TASK/INTERVAL ADJUSTMENTS-TOP-LEVEL CHART Task/Interval Note 1 Is the task based on certification or other regulatory requirement?
Note 2 Is a revision within End -NO the authority of the Reliability Program?
MSI:
Systems Note 4 Operator Programs:
FEC 5/8 FEC 6/7/9 Zonal/EZAP Structure: L/HIRF Appearance/ Regulatory Authority Note 3 Cleanliness/ or Source Requirement Administrative Tasks Appendix B Appendix C Appendix E Appendix F Appendix G Appendix H Appendix I Notes:
1. Supplemental Type Certificate (STC)-derived instructions for continued airworthiness (ICA) should not be treated any differently than any other task unless the STC holder's ICA documents provide specific instructions for interval management. It is a best practice for operators to coordinate with STC holders by providing product performance feedback during analysis initiatives associated with these designs.
2. Examples include: Airworthiness Directive (AD), Certification Maintenance Requirements (CMR), airworthiness limitation item (ALI), airworthiness limitation (AL) tasks, fuel tank safety (FTS) tasks, Failure Effect Category (FEC) 5 or 8 tasks "tagged" as precluding a CMR, etc.
3. Operators should not rely exclusively on type certificate holder (TCH) assignment of FEC codes. An understanding of the functions under analysis and associated consequences of functional failure is beneficial.
4. Maintenance Significant Items (MSI).
A-1
Appendix B APPENDIX B. FAILURE EFFECT CATEGORY (FEC) 5/8 TASKS Note 1. Operators may not delete FEC 5 or 8 tasks. An operator's FEC 5/8TASK1 authority to optimize FEC 5 and 8 tasks is restricted to interval changes only. Analysis of FEC 5/8 tasks should be performed by experienced Verify correct FEC code assignment (MRBR). Contact TCH if FEC personnel meeting the competency code is considered minimum per 2.1.4. incorrect.
Review TCH ICA rules. Do not countermand TCH ICA rules (if applicable). 2 Ensure data selection criteria conforms with guidance in this AC (or as accepted by carrier's CMO).
Consider alternative Is task still is task a lube Appendix task procedures, #No applicable and ·No -Yes→ task de letion, aircraft effective? or filter task?
modification, or consult TCH.
Note 2. FEC 5/8 tasks "tagged" or otherwise identified as satisfying a CCMR: TCHs should have Perform analysis of procedures in place to ensure these tasks are not appropriate data: Scheduled Define and susceptible to escalation beyond the SSA interval maintenance defects resulting implement that would otherwise be required by the CMR. from FEC 8 tasks should be Operators desiring to optimize intervals of these carefully analyzed, since sampling tasks must coordinate with the TCH to ensure the CCMR interval established by the SSA during may not reflect hidden failures in-service operational data program for the task. s certification will not be exceeded. Refer to associated with these tasks. 4 AC 25-19 Is it feasible Does the analysis Note 3. Relative to the targeted substantiate a revised No, or to apply a revised interval to a fleet failure mode and original intent. task interval and Inconclusive sub-set for remain effective?
Referto MSG-3 section 2-3-7.1 sampling?
(Table 2-3-7.1, Criteria for Task Selection) for applicability and safety effectiveness guidance. No Coordinate with the TCH when data from the MSG-3 task analysis is necessary to perform the evaluation. Revise the task interval.
Note 4. Consider communication with TCH to ensure fail-safe design limit is not exceeded.
Schedule a follow-on analysis to validate the task remained effective Retain identity and significance of safety-related tasks such as CMRs, after implementation.
ALIS, AL, FEC 5, and FEC 8.
Note 5. A typical sampling program consists of End a specified number of aircraft, an implementation plan, acceptable performance standards or criteria, performance monitoring and reporting procedures, and a timeline.
B-1
Appendix C APPENDIX C. FAILURE EFFECT CATEGORY (FEC) 6/7/9 TASKS FEC 6/7/9 Task Verify correct FEC code assignment (MRBR). → Contact TCH if FEC code is considered incorrect.
Note 1. Relative to the targeted failure mode and original intent.
Refer to MSG-3 section 2-3-7.1 Is task a Lube —Yes—→ Appendix D or Filter task?
(Table 2-3-7.1, Criteria for Task Selection) for applicability and safety effectiveness guidance.
Coordinate with the TCH when data from the MSG-3 task analysis is Ensure data selection criteria conforms with guidance in necessary to perform the evaluation. this AC (or as accepted by carrier's CMO).
Note 3. A typical sampling program consists of a specified number of Consider alternative Is task still task procedures, •No- applicable and aircraft, an implementation plan, task deletion, aircraft effective? ! acceptable performance standards or modification, or consult TCH. criteria, performance monitoring and reporting procedures, and a timeline.
Define and implement Perform analysis of appropriate data. sampling program for the task. 3 Does the Is it feasible analysis Note 2. Based on current to apply a revised substantiate a No, or performance standards revised task interval Inconclusive interval to a fleet system. and remain sub-set for effective? 2 sampling?
No, or Yes Inconclusive Is the Revise task anticipated scope, type, Yes impact to operational and/or interval. pertormance acceptable?
No Based on risk, schedule a follow-on analysis to validate the task remained effective after implementation.
End C-1
Appendix D APPENDIX D. LUBE/FILTER TASKS Note 1. Consideration volumes, rates of usage or deterioration, and the unit's ability to perform its intended function. Do not assume variables are constant. It is possible that at some Lube/Filter Tasks 1 point, rates may accelerate.
Verify correct FEC code assignment (MRBR). → • Contact TCH if FEC Note 2. Relative to the targeted code is considered failure mode and original intent. incorrect.
Refer to MSG-3 section 2-3-7.1 Ensure data selection criteria conforms with guidance in (Table 2-3-7.1, Criteria for Task this AC (or as accepted by carrier's CMO).
Selection) for applicability and safety effectiveness guidance.
from the MSG-3 task analysis is Coordinate with the TCH when data Is task still Consider alternative necessary to pertorm the evaluation. applicable and effective? 2 task deletion, aircraft task procedures, modification, or consult TCH Note 3. The selected interval should be based on the consumable's usage rate, the amount of consumable in the system (if applicable), and performance deterioration characteristics.
Typical operating environments and climatic conditions are to be considered when assessing the deterioration characteristics.
Consider primary and peripheral purpose of consumable materials (e.g., does it also provide a means of compliance with the operator's aircraft corrosion objectives).
Note 4. If alternative material (lubricants, filter elements, etc.) are considered to extend an interval, consider compatibility of alternative Perform analysis of appropriate data.
products with existing system features and design performance. Caution should be exercised for material compatibility (e.g., lithium grease and compatibility).
Does the analysis Revise task substantiate a scope, type, revised task interval and/or and remain Interval. 3 effective? 2 No Initiate change Does data in consumable *Yes- analysis support introduction material. of alternative consumable material? 4 No End D-1
Appendix E APPENDIX E. ZONAL/ENHANCED ZONAL ANALYSIS PROCEDURE (EZAP) Zonal/EZAP Tasks 1 Review TCH ICA rules. Do not countermand TCH ICA rules (if applicable). 2 Ensure data selection criteria conforms with guidance in this AC (or as accepted by carrier's CMO).
Consider alternative Is task still task procedures, -No- applicable and task deletion, aircraft effective?
modification, or consult TCH. Yes Consider density, type and function (constant and intermittent current loads) of wiring and interconnection systems in the zone under review.
Will interval or task Does the zone scope adjustment maintain contain L/HIRF -Yes- acceptable levels of accumulated and No protection? s potentially flammable contamination? 4 Analysis of L/HIRF and zonal routine task Ensure the analysis includes review of TCH cross findings should take into consideration reference appendices that correlate systems/structures maintaining L/HIRF protection. 6 tasks satisfied by zonal tasks (as applicable).
Perform analysis of appropriate data.
Will the interval and/or task scope adjustment maintain acceptable levels of L/HIRF protection? & Is the task used Does the analysis
•Yes- to take credit for DT *Yes- substantiate a revised for repairs or task interval and remain alterations? effective?
Review previous repair or No alteration records to identify repairs or alterations which may No require individual tracking based No on new interval.
If applicable, Revise task track repairs scope/type and alterations and/or separately interval.
End E-1
Appendix E E-2 Note 1.
- Consider aircraft structure, systems, and installations within the zone to ensure unintended degradation or loss of function will not occur.
- Traceability of revisions to approved electrical wiring interconnection system (EWIS) instructions for continued airworthiness (ICA) to include task, intervals, procedures, protections, and cautions must be maintained.
- As applicable, operators must apply any additional procedures or restrictions based on their compliance document requirements.
- Deletions and task changes (other than task intervals) of EWIS tasks must be approved by the Aircraft Certification Service office via the operator’s Principal Maintenance Inspector (PMI).
- Revisions to EWIS task intervals must be approved by the PMI. (Refer to 14 CFR § 121.1111(e).)
Note 2. Example:
Some zonal tasks may partially satisfy damage tolerance requirements which must be performed at originally-established limits after a certain fatigue threshold. Intervals may be escalated prior to that threshold, but must be adjusted to the original levels at the threshold.
Note 3.
- Relative to the targeted failure mode and original intent.
- Refer to Maintenance Steering Group – 3rd Task Force (MSG-3), volume 1, section 2-3-7.1 (Table 2-3-7.1, Criteria for Task Selection) for applicability and safety effectiveness guidance.
Note 4. This evaluation doesn’t necessarily include the concept of actually measuring contamination or accumulation rates. However, each task adjustment should be sufficiently substantiated, which includes whether the desired results will continue to be achieved at the revised interval. Refer to AC 25-27, AC 120-94, and AC 120-102 for additional information on contaminants.
Note 5. Lightning/High Intensity Radiated Fields (L/HIRF) protection may include:
- Wires, shields, connectors, bonding straps, raceways between connectors.
- L/HIRF protection within conduit or heat shrink or other covering.
- Non-metallic structure with conductive mesh and/or antistatic coatings.
Note 6. Consider:
- The environment and effects of corrosive produces, condensation, temperature, and vibration on the protection.
- Increased susceptibility to damage during maintenance or operations (e.g., where connectors could be stepped on, or effects of deicing fluid on a connectors during winter operations).
Note 7. Awareness of these relationships support a quality analysis. Zonal working groups may have modified zonal intervals to accommodate these interfaces.
Note 8.
- For example, findings associated with bonding straps, lightning wicks, tank plate wiring/connector bonding, etc.
- Ensure unintended consequences such as Environmental Deterioration (ED) or Accidental Damage are not introduced due to frequency of access/egress.
Appendix F APPENDIX F. STRUCTURE Note 1. General Information:
- The actuating portions of items such as landing gear, flight controls, doors, etc. are treated under systems analysis. Structures Tasks'
- Dynamic components such as hinge bearings are treated as system component.
- Attachment fittings of the actuators to the airframe are treated as a structure analysis. insure data selection criteria conforms with guidance ir
- Structure-to-structure attach points, not his AC (or as accepted by carrier's CMO).
otherwise associated with an aircraft system
(e.g., pylon attach fittings and diagonal braces) that feature bearings are be treated as structure. Ensure TCH ICA
- Special consideration should be given to Does the TCHICA document guidance analysis associated with attach points to instructions for structures document contain specific -Yes— → is followed structure since the structural analysis may not program adjustment? (e.g., MPD section provide full consideration for wear and 9), and...
deterioration. These analyses should be compared with the appropriate system analysis, as applicable. NO
- Wear is typically found in/at bushings, bearings, stops, latches, locks, tracks, guides, Ensure data selection criteria conforms with guidance in cams, rollers, cables, pulleys, or floors. Wear can this AC (or as accepted by carrier's CMO).
influence loads and strength, lead to inaccurate positioning and adverse free play or change resistance to environmental deterioration.
Wear can be systematic for parts intended to be Is task still Consider alternative task normally not come in contact or should not be in contact, or random for parts that should applicable and effective? : task de letion, aircraft procedures, subjected to relative motion.
modification, or consult TCH.
- Non-metallic structure is susceptible to damage and/or deterioration such as disbonding and delamination. These structures are not normally susceptible to Perform analysis of appropriate data.
degradation due to the environment
(e.g., corrosion). Special consideration should be given for non-metallic structure and any uniqueness associated with applicable damage sources.
Does the Appendix H. Follow End analysis Is the task AD requirements for No change to task substantiate a a corrosion Is the CPCP interval Yes type, scope, or revised task interval detection AD-mandated? adjustments.
interval. and remain task?
effective?
Note 2.
- Relative to the targeted failure mode and Ensure substantiating data original intent. "Is the task used to take accounts for
- Refer to MSG-3 section 2-3-7.1 credit for DT for repairs or (Table 2-3-7.1, Criteria for Task Selection) for aterations? previous findings and corrective applicability and safety effectiveness guidance. actions. *
- Coordinate with the TCH when data from the MSG-3 task analysis is necessary to perform Note 4. The program is expected to control the evaluation. corrosion to Level 1 or better. Initial programs assume an aircraft is operated in Note 3. Consider all damage sources: records to identify repairs or alferations Review previous repair or alterations a typical environment. If the analysis reflects a trend in corrosion defects that Environmental Deterioration (ED) (corrosion, which may require individual tracking exceed Level 1, the corrosion control stress corrosion, delamination, disbonding, based on new interval. program for the affected area should be etc.); Fatigue Damage (FD); Accidental reviewed by the operator with the Damage; and Wear Damage (WD). objective to ensure Level 1 or better.
Revise task scope/type and/or End accomplishment interval.
F-1