I have a relative who works on helicopters and at one point he was involved with the Chinook. IIRC (we were talking over a few bevvies) the ac has to have it's glass cockpit removed, an analogue one fitted and then be upgraded to glass again. He also mentioned that the contract to carry out this work was biased against early completion with more pay being given to workers who "stayed with the program" (a sort of retention bonus with unintended consequences).
Anyone care to comment or did I just misunderstand?