A-B-C-D check Maint inspections

[ChuckPerry]

Speaking only of the A320,and speaking only for our phased maintenance program at United,  the normal C check interval for an A320 is eighteen months. In most airlines, where C's are done as complete, five or so day checks, the first one is a 1C or C1 (depending on the airline, same thing), second is 2C or C2, etc. A C4 (also C8, C12, C16, etc) check is a "mini-D" - it has more structural inspections. A C check can be thought of as mostly a mechanical check. You're looking at the operation of components, wear, etc, and not really at the frames, stringers, ribs, etc.

The interval for a D check is seven years for the first one, then five years after that. Also, when a D check in completed this 'resets' the time cycle for C, B, and A checks for that aircraft.. something that doesn't seem to happen in Airwaysim???   

Also for some of our newer aircraft (B777, B787) the D check's have been eliminated entirely...

[LemonButt]

All checks reset the lesser checks, so if you do a D it also counts as an A, B, and C.

IRL the time period is based on flight hours versus time, but AWS uses a fixed time period for simplicity.