What is the flexibility allowed to the person or organisation responsible for the aircraft continuing airworthiness when it comes to the planning of Aircraft Maintenance Programme (AMP) scheduled maintenance tasks with intervals expressed in calendar time?
1. Purpose of the document
The Agency was requested by the industry for additional guidance on the application of the airworthiness rules in respect to certain specific issues particularly affected by the current COVID-19 crisis. One of those topics concerns the obligations of the person or organisation responsible for continuing airworthiness of aircraft when it comes to the accomplishment of Aircraft Maintenance Programme tasks with intervals expressed in calendar times. Accordingly, the Agency prepared this additional, temporary, guidance, which complements the existing AMC/GM to Commission Regulation (EU) No 1321/2014.
The guidance provided in this document is primarily intended for ‘Part-M’ aircraft, but can be used also as regards ‘Part-ML’ aircraft, except that in case of ‘Part-ML’ aircraft, the competent authority does not need to be involved if an AMP task is to be postponed, as this is done under the responsibility of the aircraft owner or the organisation responsible for the aircraft continuing airworthiness. This person or organisation may also decide, if necessary to revise the AMP, which will not involve the competent authority.
2. Description of the issue
During the COVID-19 crisis, a large number of aircraft is being parked / stored at different and partially remote locations. This guidance document was prepared based on an assumption that these aircraft have been subject to parking/storage procedures defined by the Type Certificate (TC) Holder (those parking and storage procedures are usually contained in a chapter of the Aircraft Maintenance Manual (AMM e.g. Chapter 10). If the existing AMM does not contain parking/storage procedures, the TC Holder should be contacted.
Note: It is not necessary to revise the AMP to include the parking/storage tasks to be followed.
During the COVID-19 crisis, the parked/stored aircraft are not operated and consequently the AMP scheduled maintenance tasks based on ‘Flight hours’ and ‘Flight cycles’ are not impacted. On the other hand the AMP scheduled maintenance tasks based on intervals (and threshold, if applicable) expressed in calendar times need to be considered. Indeed, some of the calendar time based scheduled maintenance tasks will become due during parking/storage period.
In the normal practice, following the principles of AMC M.A.301(c) and point 4 of Appendix I to AMC M.A.302 and AMC M.B.301(b), if a scheduled maintenance task cannot be performed within the interval approved in the AMP, its postponement may be allowed in accordance with pre-defined ‘permitted variation’ agreed with the CA in the AMP.
3. Considerations in the frame of COVID-19 crisis
3.1 Postponement until the end of parking/storage period
In the current situation, it may not be always feasible, to perform the calendar scheduled maintenance tasks of the AMP in due time, or within the permitted variation specified in the AMP.
In such cases, it is acceptable for EASA to plan the accomplishment of these tasks (even if they have become due multiple times during the parking/storage period) at the next suitable opportunity (e.g. next weekly check of storage/parking procedure), or at the end of the storage/parking period, but in any case before the next flight, as part of the work package necessary for the de-preserving/de-storage of the aircraft.
Note: Certain AMP scheduled maintenance tasks may be assessed as unnecessary because they are covered by equivalent tasks in the parking/storage procedures put in place.
3.2 Postponement beyond return to service
If exceptionally, a calendar task needs to be postponed until after the return to service and beyond the AMP permitted variation, the aircraft owner or CAMO/CAO should receive advice from the TCH or the Design Approval holder (DAH) on such postponement and on the subsequent due date after the accomplishment.
The applicant should then submit such postponement, together with the proposed technical justification, including if appropriate, a risk assessment, for approval by the CA.
The CA should consider the following conditions, mitigating actions or any other elements which the CA deems necessary, when allowing a postponement of a due calendar task after return to service:
- An approved maintenance organisation has applied the appropriate parking/storage procedures during the full period.
- The owner/CAMO/CAO has monitored what AMP tasks are due (M.A.708(b)(4), CAMO.A.315(b)(5) and CAO.A.075(b)(7)).
- This does not apply to mandatory continuing airworthiness instructions (MCAI) such as AD or ALS tasks.
- The environmental conditions where the aircraft was parked/stored have been taken into consideration. Certain calendar tasks may be more relevant to a particular storage environment, e.g. wet, salty conditions propagate corrosion.
In addition, the importance of the AMP task (e.g. based on MRB task type/source/category, reliability-alert task), the performance of the CAMO/CAO quality system, and if applicable the review of the risk assessment performed by the applicant, should also be considered.
Based on the above elements, it may be possible to allow an exceptional (one-off) postponement, not exceeding the following:
(i) AMP task interval of 1 year or less: up to 3 months
(ii) AMP task interval of more than 1 year, but not exceeding 2 years: up to 4 months
(iii) AMP task interval of more than 2 year, but not exceeding 3 years: up to 5 months
(iv) AMP task interval of more than 3 years: up to 6 months.
Such postponement should be calculated from the original AMP task due date, unless otherwise agreed with the competent authority.
The subsequent due date should also be part of the CA approval.
The Aircraft continuing airworthiness record system, and if applicable, the aircraft technical log system should properly record such agreement and the effective accomplishment date.
Depending on the length of the COVID-19 crisis and the future annual utilisation of the aircraft, the CA may also require to the owner/CAMO/CAO an ad-hoc review of the AMP pursuant to M.A.302(h).