I was going to say why bother, my radio engineer just seems to borrow mine..
Depends how deep you go, some small screwdrivers etc for opening cases and removing avionics fronts, some small allenkeys or spline drives for refitting radio knobs, really long screwdriver or keys for pulling avionics boxes brass screwdriver for adjusting compasses, have seen brass house keys cut to fit. Torch...
After that if you are going to get into radio fits crimps... wire strippers etc
You are then starting to enter the expensive test set end of the game. A multimeter, though I have a digital fluke myself, our engineer seems to prefer a analogue needle version as he says it is faster reacting.
Not a radio engineer, but your best bet is to ask the licenced guy you are going to work with, he should be able to tell you what you will need.