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Airworthiness Advisory Circulars - Part 6-74 - Removal of Inoperative Equipment

Part 6 - General advice

AAC 6-74

Removal of Inoperative Equipment

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There seems to be a misunderstanding that inoperative equipment included in an aircraft's approved minimum equipment list (MEL), or approved as permissible unserviceabilities under CAR 37, can be removed for repair while the aircraft continues in operation.

However, MEL or CAR 37 approvals do not automatically allow operations with equipment removed. Removals of equipment from an aircraft are modifications and hence must be carried out in accordance with CAR 42U. The regulation applies to all equipment related to the airworthiness of the aircraft, including optional equipment not required by the type design standards or operational rules. This requirement is necessary for safe operations of the aircraft, as improper removals may have adverse effects on the aircraft weight and balance or operations of other critical aircraft systems.

Therefore, unless the design of a removal is specified in the aircraft's approved maintenance data, it must be approved by a CAR 35 authorised person. Approved maintenance data is defined in CAR 2A and includes the manufacturer's maintenance manual, the master minimum equipment list for the aircraft type, and instructions issued by the CAR 35 authorised person who approved the design and installation of an optional equipment.

Once the design of the removal has been approved, an operator can include the procedures for removing the equipment in the maintenance (M) procedures for the aircraft's MEL.