LED, LCD and segment displays
Chosing the correct displaying material is very important. You do not want to end up with 7-segment displays that are so small that you can't solder them anymore, yet you do not want too big displays either. Not soldering wires to the displays but using a PCB is a very wise choise to make. Only problem is then .. there are different types of displays, different pin-layouts and different producers. So go find your correct PCB's ...
No really .. I hope that in time it will be possible to find all recourses here to find the correct PCB's here in no time.
An other sollution might be LCD's. I don't know for most types of airplanes but for sure the type I am building does not even use 7 segment displays. It uses white Negative backlit text LCD's.
Find everything in detail on their pages: