REFLECTOR: Uncommanded pitch trim up

[John Dibble via Reflector]

2 1/2 years ago I reported experiencing uncommanded pitch trim up. I 
suspected that the solid state relay was the source of the problem as I 
had other problems with it in the past.  I wired the trim buttons direct 
to the trim motor and had no problems for 200 hours. Today the problem 
happened again, so it looks like the problem is either in the stick 
(where the trim buttons are) or the trim motor. Here are the details.

It only happens when I'm in the pattern.  IIRC it begins when I'm abeam 
the numbers where I do my GUMP. I have a thermistor on the IVO prop and 
I hold the toggle to fine pitch until I see the current increase to 15 
amps, indicating it's at the end of the travel.  The problem usually 
goes away after I turn to final.  Having learned from car window control 
battles with my kids, I know that if both the up and down buttons are 
pushed at the same time, that nothing happens.  So I held the trim down 
button to stop it from further trimming up.  Once the stick began moving 
forward, I knew the problem was gone.  Any ideas what the problem is?

John

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