Hi Robert,

 

My understanding from talking with the RAC guys, who make the trim components I installed in my Legacy, is that stuck (runaway) trim is unlikely.  (Actually, they said it was impossible, but I find it hard to use that word.)

 

The trim servo must receive power to operate.  A runaway can only occur if either the trim switch or the trim relay is stuck in the "on" position.  If that happens, moving the trim switch to the opposite position should almost certainly cause the switch or relay to open, clearing the problem.  (Wiring faults could also cause runaway trim, but I was careful to protect the wiring when I installed it and therefore do not consider this cause to be a realistic possibility during the time I own my Legacy.) 

 

I've given this some thought and have decided that runaway trim is possible, but unlikely.  I've decided that the additional parts count and complexity to reduce the chance of an already unlikely runaway trim isn't justified.  I've practiced this and believe I can control the airplane with full trim if I slow it down, although my arm would get tired after a while.

 

Best,

Dennis Johnson

Legacy, 140 hours