If there was an engine problem, you call the engine shop. If there was a sheet metal problem, you call the sheet metal shop, etc., etc.
Oh boy, that kinda thing reminds me of when I worked as a specialized cabinet maker for the industrial display companies. We built huge displays for Industrial Trade Shows. We did all functions of the displays at the shop. Once the displays were complete and shipped off to the big exhibition centers we would then go there to supervise the assembly. We could touch nothing. We had to call a carpet layer to unroll the carpeting, call a carpenter to assemble the component cabinetry, call an electrician to plug in a lamp etc. If you needed an extension cord plugged in you had to call the electrician.
That's the short version 
In civilian life these groups are called "Union Engineers" 
Did you actually see the Spruce Goose? Howard Huges was quite a guy. Weird but special
