Had the best troubleshooting day of my career last Tuesday

I was working on a 737 that had an intermittent GPS dropout that had been ghosting the senior guys for weeks. Pulled the LRU, checked the coax, nada. Then I just sat there watching the rack for 20 minutes and noticed a tiny flicker on the power LED when the AC cycling kicked on. Traced it to a pin on the power supply connector that was slightly bent. Replaced the connector, 3 hours of testing, not a single dropout since. The lead tech bought me lunch and everything. Anyone else ever catch a weird intermittent by just staring at the box long enough?

2 comments

2 Comments

the_zara16d ago

Wait, AC cycling shouldn't flicker the power LED on a 737.

henry_kelly5415d ago

Has anyone else noticed how often we just assume complex systems have simple explanations? Like, the AC cycling thing being blamed for a power LED issue - it's the same logic people use when their car's check engine light comes on and they blame the gas cap. I've seen it with my own fleet of trucks, where a battery drain turned out to be a corroded wire, not the alternator. We always reach for the easy answer first, especially when it's something we half-remember from a YouTube tutorial. But real problems (like in planes or even just old houses) love to hide behind layers of symptoms that all look alike at first glance.