Some accidents and incidents occurred which have been linked to errors and misunderstandings with regard to the eligibility of components installed on the aircraft (Part Number, SB, AD, modification status, etc.).
M.A.301, in point 6., identifies the accomplishment of the modifications as one of the continuing airworthiness management tasks to be performed by the owner/operator. Proper control of such modifications is required to maintain the compliance status of the aircraft.
For large aircraft and those used in commercial air transport (CAT), Part-M Subpart-G requires for every aircraft managed, that the CAMO carries out a certain number of continuing airworthiness management tasks. However, in Subpart-G, M.A.708, M.A.704, and in the Appendix related to the Continuing Airworthiness Management Exposition (CAME), the requirement to manage the continuing airworthiness of the aircraft does not state clearly that there should be a continuous control of the configuration of the aircraft which has to be taken into account during the maintenance actions carried out on the aircraft.
Part-M Subpart-E requires in M.A.501(b) that ‘Prior to installation of a component on an aircraft the person or the approved maintenance organisation shall ensure that the particular component is eligible to be fitted when different modification and/or airworthiness directive configuration may be applicable’. Such responsibility is put on the maintenance organisation, while the control of the configuration of the aircraft is the responsibility of the operator/owner/CAMO.
A similar requirement is included in 145.A.42(b). This indicates that Part-M and Part-145 do not clearly allocate the responsibilities for these tasks between the CAMO and the maintenance organisation.
Moreover, the case of maintenance organisations for non-large aircraft not operated in CAT is also unclear, as M.A.608 in Subpart-F does not include any requirement for the control of components similar to what is defined in 145.A.42(b).
EASA is putting together a work group to analyze how to improve communication framework between part M and part 145. Clear goal is to reduce maintanance errors caused by uncertainty on the aircraft modification status.
Aviation Island, as CAMO services provider, will closely monitor evolution on this issue.