The A, C & D Of Passenger Plane Maintenance - Simple Flying


Have you ever wondered how often aircraft receive checks and maintenance and how this is structured? With so many aircraft in service, tight schedules, and lots to look at, this is a well planned and formalized process. This article takes a look at the main – so-called A, C, and D – checks that all aircraft regularly undergo.

Qantas A380 LAX
Qantas A380 maintenance hangar. Photo: Qantas

Maintaining their fleets

All aircraft, after they enter service, follow a continuous and rigorous program of inspection and maintenance. This is defined by the appropriate regulatory authority (FAA in the US, EASA in Europe, for example) for each aircraft operator. And these authorities can fine airlines for errors and omissions.

The timings and details may vary slightly, but a general principle followed by all operators is to break the maintenance into different types – usually lighter ‘A checks’ that occur regularly, and more heavy ‘C’ and ‘D’ checks less regularly.

As well as these formalized inspections and maintenance, aircraft, of course, receive constant ongoing line maintenance. Things like tires, brakes, fluid levels, and any other issues flagged by pilots (or onboard systems) are checked on the ground between flights.

British Airways aircraft inspection
On the ground aircraft inspection. Photo: British Airways

The A checks – regular, light maintenance

The A checks are lighter checks that take place around every 400 to 600 flight hours (or every 200 to 300 flights), varying between aircraft types and age.