Grunf
As for what N380UA says on the fact that airlines send their engineering reps to control the design process - I can just very politely say, hardly.
It may be handled differently nowadays under the pretext of saving money but it wasn’t too long ago that that was standard practice. I have seen Swissair, Lufthansa, Alitalia, ANA, and a bunch of other airlines on site doing just that, construction supervision.