Jedi's problem wasn't that he knew how to use it but that he knew how to use it properly! He'd write what the defect was, because it simply was that the instrument failed. However this was the wrong way of course as he was meant to write, "instrument showing fluctuating indications"! (me thinks Jedi suffered a lot from doing things properly but the wrong way!) See in the second case 'someone' could simply write something along the lines of "Ground tested serviceable" and he'd probably find that things hadn't really improved all that much. The way Jedi and others would write it, the aircraft would sit on the ground until the instrument had been shipped from somewhere in Aust. and installed because there were none on the shelf. Some two weeks would pass. am i right jedi?
WOMBAT.