I was flipping channels a week or two when I came across a show on the Airbus. It must have been a year or two old as it was all praise on how well things were working out with parts being built all over Europe.
Anyway, this was on the very first one to be completed, and they were showing one of the last parts to be put on the plane. It was somewhere on top near the tail. I have no idea what it was for, but it looked like a small intrument package. There was a cable connection that had to be made once it was to be inserted.
To the embarrassment of the engineer/technician/factory worker, the connection was about two inches too short.
They could not install that last piece. It was not clear how they resolved that issue, but I was thinking to myself, I sometimes have problem when I build things myself, but if my bookcase falls apart no big whoops.
I would think these things would be engineered to the point where everything fit, the first time.