Sofema Aviation Services (SAS) considers the requirements related to Repair Evaluation Guidelines & Repair Assessment Programme in compliance with AMC4 CAMO.A.305(g) Personnel requirements (ED Decision 2020/002/R) – Related to AMC 20-20 ‘Continuing Structural Integrity Programme’.
Please Note – Sofema Aviation Services offers training in support of the understanding regarding the regulatory obligations available at this link
Historical Considerations
Early fatigue or fail-safe requirements did not necessarily provide for the timely inspection of critical structure so that damaged or failed components could be dependably identified and repaired or replaced before a hazardous condition developed.
Note – Application of later fatigue and damage tolerance requirements to repairs was not always fully implemented according to the relevant certification bases.
Repair Evaluation Guidelines – Purpose
Repair Evaluation Guidelines (REG) are intended to:
- Assure the continued structural integrity of all relevant repaired and adjacent structure, based on damage-tolerance principles, consistent with the safety level provided by the SSID or ALS as applied to the baseline structure.
- To achieve this, the REG should be developed by the TCH and implemented by the Operator to ensure that an evaluation is performed of all repairs to structure that is susceptible to fatigue cracking and could contribute to a catastrophic failure.
AAWG -Surveys
Even the best-maintained aircraft will accumulate structural repairs when being operated. The Airworthiness Assurance Working Group (AAWG) conducted two separate surveys of repairs placed on aircraft to collect data.
- The evaluation of these surveys revealed that 90% of all repairs found were on the fuselage, hence these are a priority and Repair Assessment Programmes (RAPs) have already been developed for the fuselage pressure shell of many large transport aeroplanes not originally certificated to damage-tolerance requirements.
- 40% of the repairs were classified as adequate and 60% of the repairs required consideration for possible additional supplemental inspection during service.
Note – following further studies by AAWG working groups it has been agreed that repairs to all structure susceptible to fatigue and whose failure could contribute to catastrophic failure will be considered.
(Ref. AAWG Report: Recommendations concerning ARAC taskings FR Doc.04-10816 Re: Aging Airplane safety final rule. 14 CFR 121.370a and 129.16.)
High Time & High Cycle Airframe Considerations
As aircraft operate into high cycles and high times the ageing repaired structure needs the same considerations as the original structure in respect of damage-tolerance.
- Existing repairs may not have been assessed for damage-tolerance and appropriate inspections or other actions implemented.
- Repairs are to be assessed, replaced if necessary or repeat inspections determined and carried out as supplemental inspections or within the baseline zonal inspection programme.
- A damage-tolerance based inspection programme for repairs will be required to detect damage which may develop in a repaired area before that damage degrades the load-carrying capability of the structure below the levels required by the applicable airworthiness standards.
Repair Evaluation Guidelines
The Repair Evaluation Guidelines (REG) should provide data to address repairs to all structure that is susceptible to fatigue cracking and could contribute to a catastrophic failure.
The REG may refer to:
- The Repair Assessment Programme (RAP),
- Other existing approved data such as SRM and SBs or
- Provide specific means for obtaining data for individual repairs.
SRM & SB Implications
- Documentation such as the Structural Repair Manual and service bulletins needs to be reviewed for compliance with damage-tolerance principles and be updated and promulgated consistent with the intent of the REGs.
- Where repair evaluation guidelines, repair assessment programmes or similar documents have been published by the TCH they should be incorporated into the aircraft’s maintenance programme according to Part-M requirements.
- This fatigue and damage-tolerance evaluation of repairs will establish an appropriate inspection programme or a replacement schedule if the necessary inspection programme is too demanding or not possible.
Please see the following related to Part CAMO Transition Support – https://sassofia.com/download-area/#part-camo-transition-support
For additional questions or to register for training please email team@sassofia.com
Tags:
(EC) Regulation 1178/2011, AMC 20-20, aviation, Continuing Structural Integrity Programme, Part CAMO, REG, Repair Assessment Programme, Repair Evaluation Guidelines, SAS blogs
