Just realized I fixed a weird autopilot fault by checking the harness routing

Working on a Citation in Wichita, the autopilot kept dropping out during climb tests. I traced it for hours before noticing the main avionics harness was rubbing against a hydraulic line bracket, wearing through the shielding. Re-routed it with some extra chafe guard and the fault cleared right up. Anyone else had a gremlin turn out to be simple chafing?

2 comments

2 Comments

perez.thea13d ago

Honestly, I used to get so mad chasing electrical issues, convinced it was a bad box or software. I'd skip right over checking the physical run of the wiring. A similar thing happened on a King Air where a trim issue was just a bundle sitting on a sharp edge. Now it's the first thing I look for, saves so much time. It's crazy how often the fix is just moving the wire a few inches away from something.

schmidt.karen13d ago

We had a Cessna 172 with a flickering landing light for months. The mechanic finally found the wire harness was rubbing against a control cable bracket. A couple zip ties to reroute it and the problem was gone for good.