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Steve Brown
10-20-2007, 09:22 AM
During my last before-takeoff check I noticed the Altrak was not working. To check, I engage it, then gently move the stick for/aft a little to be sure I can override the hold. This time there was no resistance.
The brass screw on the servo arm was sheared. I'm assuming it is designed to do so in case of servo runaway.
Background:
Our last flight/s were to CO from CA. One the way to CO we noticed some squeaking sounds coming from the rear. I assumed were able to hear the canopy squeaking or something because the engine was at low power levels at high altitude (15,500).
Same thing happened on the way home, at first. Then I never noticed it anymore, but the altitude hold virtually quit working.
The light would flash when it got out of altitude range, but would not bring it back in.

So, today I'm planning to remove the Altrak box and the servo motor to send them back to Trutrak for repair. Probably only one has a problem, but I'm not sure which.

Any additional insight would be appreciated.

DarylT
10-20-2007, 09:35 AM
From the sound of it there was binding in the rigging in the rear somewhere. That would cause the servo screw to shear. From everything I have read about Trutrak Steve I would think you could check for the source of the binding. Once resolved I think you could just replace the shear screw.

http://www.trutrakflightsystems.com/docs.htm

I just looked at their site to see if this was something you could replace yourself but I don't see anything about the screw except that it is a shear screw for this purpose.

Steve Brown
10-20-2007, 09:50 AM
Thanks Daryl,

I have searched Trutrak's documentation and have yet to find the shear screw even mentioned. Where did you find that?????