Had a talk with a retired KC-135 guy that flipped my thinking on troubleshooting

Last month I was working a bench in Tulsa and this old timer who used to fly on tankers stops by. He said they'd just swap boxes until the light went green, no diagnostics at all. It made me realize I spend way too much time chasing schematics when a simple swap might save me an hour or two. Has anyone else run into a situation where the 'right' way took longer than the hack way?

2 comments

2 Comments

the_jana1mo ago

My buddy who works avionics on C-17s told me they do the same thing sometimes. He said the manual says run 20 step fault isolation but the guys on the line just start swapping LRUs until the fault goes away. I get why they do it though when the jet needs to fly and you got limited time. Makes me wonder how often we overthink stuff that could be solved with a quick part swap.

ward.piper1mo ago

You're glossing over the fact that the manual's 20 step process exists for a reason (like catching intermittent faults that a quick swap won't fix). Swapping parts until it works is just playing whack-a-mole with the symptoms, not the root cause. I've seen crews shotgun three LRUs on a single fault, only to have it come back two flights later because the real issue was a chafed wire they never checked. The manual steps might be slow, but they save you from burning through expensive spares and chasing ghosts down the line.