Trim servo goes down, but not up

[GTWreck]

'87 Mooney 205 with KFC-150 Autopilot.  On a recent trip, when I got to the pattern at my destination, I noticed that I wasn't getting any up trim past a certain point.  On the ground, down trim worked just fine, but up wouldn't go much further than the bottom of the 'takeoff' area on the indicator.  Moving it manually past this point was not a problem.  I flew back home with it in this state and had the same thing occur in the pattern at my home field. 

The next day, I went to the hanger and found that the up trim did not move at all, but down still worked fine.  I could hear the motor turning, but it was not moving the sproket.

I removed the servo and sent to an avionics shop, which has said that the servo checks out fine, except that the motor "turns too fast". 

 

Any other ideas?  Could a fast motor be a culprit?

[OR75]

I am curious as to what you find out.

my electric trim seems to struggle depending on the position and direction. one thing I noticed is that the trim can also be difficult to turn manually. I am wondering if the torque tubes are aligned correctly.

pro you require more effort in one direction when you turn the trim wheel manually ?

[Cabanaboy]

That happened to me on final on Friday, electric trim did not want to move. Seemed to move okay on the ground, maybe a little slow.

[FBCK]

I had the same problem, the trim servo motor finally gave up and the manual trim required a lot of force to move when it was very cold outside (-15c).  Its currently getting a rebuild as I write this, I'm expecting $1500 or so, basically they replace everything but the casing I understand (KS272 on a KFC200).  After the trim motor was taken out the manual trim wheel was very easy to turn.  I will update this when the servo gets put back in, might be a couple of weeks.

[FBCK]

Just an update on my trim issue, had the trim servo motor removed and rebuilt, totall cost was $880 and now it works like it should.

[Seth]

I had a similar issue in my 1983 M20J Missile 300 during the prebuy.  I noticed that the electric elevator trim simply "skipped" or "skidded" around and was not "smooth."

It turned out that the the trim "clutch" had to be rebuilt/overhualed, and the cost was similar to what FBCK quoted.  So that amont was reduce from the offer price and it has worked flawlessly since the repair at the time of purchase.

Take care and good luck.

-Seth

[carusoam]

Good buying skills Seth!