this question of repairing planes is something I personally would also like to see happen in the future - here is one scenario:
Since I fly a 51 this'll be easy -
If I take a 1 ping rad hit

and nurse the plane back home - and get her to a hangar or a repair pad, then I should park the plane and start the wait for the repair. If we were alloted a certain amount of repair crew per field - I could either wait in a queue or lineup - and fly another plane other than the 51 til she is repaired, or come back after the alloted time to go again. whether or not i can exit the game is another matter for the wait - but this again is just ideas...
I don't know about time restrictions to replace parts but it seems reasonable that other than having to land missing a gear most parts could be repaired in a reasonable amount of time
If I take an oil hit and leak her dry - they can patch the hole and refill that puppy with Pennzoil
If I lose an aileron or rudder - they can attach a new one with some ease.
All in all - repairing airframes should be as or more common as getting your gv repaired out in the field???
Again these are just ideas