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?}
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.
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.