Airworthiness and Maintenance: Certificates, Defects and Release
The airworthiness chain
Airworthiness rests on three linked elements: the type certificate (design approved), the certificate of airworthiness (individual aircraft conforms and is maintained), and the maintenance organisation approval (who may do the work). Traps mix these up - for example, asking whether a type certificate permits flight; it does not.
Continuing airworthiness
Know the roles: the approved maintenance organisation performs work; the continuing airworthiness management organisation tracks and plans it; the certifying staff release the aircraft to service. A common question presents work done by an unapproved person - the answer is that the aircraft is not airworthy for release until approved work is certified.
Defects and MEL
A defect must be recorded and, if it affects airworthiness, rectified before flight unless deferred under the MEL or a permitted deferral. The commander has authority to refuse an aircraft, and must not accept an aircraft known to be unairworthy. Traps include treating a deferred defect as no defect - the MEL may impose operating conditions.
Maintenance releases and checks
Distinguish the daily or pre-flight inspection, periodic checks and the maintenance release. The release certifies that the work has been done; it does not certify that no defects exist beyond those recorded.
Worked example
After maintenance, the engineer signs the release but the defect log still shows an open item not covered by the MEL. The correct answer is that the aircraft is not airworthy because an unresolved defect outside the MEL prevents release. Rule of thumb: design approval, individual approval, work approval - all three must be in place.
Mass and balance
Loading must remain within the approved envelope for the whole flight, including fuel burn effects.