That electrical fault that took me 8 hours to find

I was working a stubborn intermittent short on a Cessna 172 last week. The circuit breaker kept popping only after 20 minutes of run time, so I spent the first 4 hours checking the usual suspects like the alternator and voltage regulator. Turned out it was a chafed wire behind the firewall that only made contact when the engine vibration hit a certain frequency. I finally found it by running the engine on the ground and using a thermal camera to spot the heat signature. Has anyone else had a fault like this that only shows up under specific conditions?

2 comments

2 Comments

calebw501mo agoTop Commenter

Whoa, thermal camera is genius. I need to borrow one for my own plane.

brookep621mo ago

Borrowed one from my buddy last month and found a hot wire behind the dash I never would have caught.