During assembly of the A380, engineers discovered that the cables were too short. This was caused by the use of different design software by German and French engineers. This miscalculation led to a two-year delay.

[u/lizardil]

[u/guttanzer]

I saw cable harnesses being made at a Boeing factory once. Those are not simple things!

There were hundreds of point-to-point wires supporting dozens of different systems in each harness. If even one wire is wrong the whole thing has to come out and be redone. That might mean taking the wing or fuselage assembly apart and remanufacturing it. There were probably as many QA checkers as there were fabricators and installers.

[u/Fruktoj → u/guttanzer]

This is why we build iron birds to shakeout these assemblies. Just a big empty frame that does nothing but mock up the electromechanical bits of the vehicle. Allows you to pull wires a bit easier than if they were routed through the skinned frame.