Airworthiness, Maintenance and Continuing Airworthiness
Certificates and continuing airworthiness
A Certificate of Registration identifies the aircraft; a Certificate of Airworthiness (C of A) certifies that the aircraft conforms to its type design and is in a condition for safe operation. Know the type certificate, supplemental type certificate, modification approval and the role of the design and production organisations. Continuing airworthiness is managed through the approved maintenance programme, airworthiness directives (ADs), service bulletins (advisory unless mandated), and the maintenance release.
Maintenance control
Know the CRS (certificate of release to service) and who may issue it; the approved organisation concept; the maintenance schedule; and the aircraft logbook entries. Know that an AD is mandatory and must be complied with within the stated period; the C of A remains valid only if the aircraft is maintained per the approved programme and all ADs are complied with. Know the minimum equipment list (MEL) and its relationship to the master minimum equipment list (MMEL).
Traps and worked example
Traps: treating a service bulletin as mandatory (only an AD is); assuming an MEL can be created by the operator freely (it derives from the MMEL and requires approval); and confusing the C of A validity with the ARC or maintenance release.
Rule of thumb: AD = mandatory; SB = advisory unless the AD says otherwise; MEL = approved deviation from the type design for dispatch, never for flight safety items.
Worked example: "An aircraft has an unserviceable item not in the MEL. May it be dispatched?" No - if the item is not covered by the approved MEL, the aircraft is not airworthy for that flight and must not be dispatched until rectified.