Warning: the 3 AM autopilot test in Mobile changed my preflight routine

I was doing a box check on a King Air outside Mobile last month and the whole pitch trim runaway test gave me a scare I haven't shaken. The annunciator lit up like a Christmas tree and the jackscrew actually cycled twice before I pulled the breaker, all while the pilot was shouting 'what did you touch?'. Has anyone else had a runaway trim simulator lie to you during a test, or is my test box just getting too old to trust?}

2 comments

2 Comments

nancy36d ago

That box is probably fine, but I learned years ago that test equipment can develop its own personality. My old handheld trim tester on a Piper Lance started giving false runaways every third or fourth check, and we finally traced it to a loose ground wire inside the unit. Took us two weeks and a very confused mechanic before we figured it out. Might be worth opening yours up and checking the connections before you blame the plane.

blair_dixon4d ago

Whoa, wait, the jackscrew actually cycled TWICE before you could get the breaker pulled? That's nuts, man. I've had test boxes act weird but not full on fake a run like it was trying to land the plane itself.