Got a stubborn LRU to talk by swapping the test set's own comm card

Had a G500 AHRS unit failing self-test with a weird comm error. The manual said replace the LRU, but I pulled the comm card from our bench test set and put it in the unit. It passed. Turns out the test set's card had a better signal threshold. Anyone else found a bench setup that's more forgiving than the real aircraft bus?

3 comments

3 Comments

gray_hall46d ago

Man, I used to think a test set had to be perfect to catch real problems. Your story changes that. A slightly off spec bench setup can actually help you find the weak link... the thing that's barely passing in the real jet. Now I see a "forgiving" test rig as a useful tool, not a bad thing. It shows you what's really on the edge.

sandra_moore306d ago

Exactly, that's the point. A forgiving rig doesn't show you the weak link, it hides it. You want the bench to be tougher than the jet, so the part fails in the shop, not the air.

emma_jones6d agoTop Commenter

Yeah, and you can even dial in that "toughness" on purpose (like adding a bit of extra load) to find the real-world failure point before it's a problem.