|Mar 23, 2014, 09:24 PM|
Elevator trim changes every flight
I have a PA Katana that flies fine except for the fact that I have to either add or take away elevator trim every time I fly it. Sometimes in the middle of a flight.
I thought it was excessive play in the elevator linkage but I changed all the linkage and added ball links.
I checked the CG between flights to make sure that the battery is in the same place. The elevator servo seems to center, at least on the bench.
Tried everything. Any suggestions?
Thanks in advance.
|Mar 23, 2014, 10:05 PM|
I just had a servo that was doing that and after I checked everything with no results, I finally changed the servo and that fixed it.
|Mar 24, 2014, 01:12 AM|
Other than a dud servo, check that the servo isn't moving in the servo cutout in the fuse, and that there is no cracking in the wood in the servo hole area.
|Mar 24, 2014, 07:00 AM|
Just to make sure:
Go to full deflection, then 'ease' the stick back toward center, and see if it stays deflected some in that direction.
(Don't let the stick bang back to center. Ease it there.)
Then full deflection the other way, and ease back to center again, and see if it stays deflected some in that direction as well.
If it's really coming all the way back to center after each of those, then that's an odd one.
Possibly a dirty/bad/loose pot, either in the servo, or in your gimbal. Or some floating bit of debris, perhaps.
It's also 'possible' though unlikely, that there's some sort of thermal drift happening.
Honestly, I'd just fit a different servo first, and go from there.
Have you given the control horn in the elevator a good wiggle, to make sure it's still secure?
Loose/cracked wood in the elevator, or the joiner between the halves?
Solar flares, sunspots, zombie invasion? I dunno. Just brainstorming
Edited to add:
|Mar 24, 2014, 12:03 PM|
I'll second the suggestion the check the control horn. I had the same issue as you, tried everything, and eventually traced it back to a loose control horn. It's worth checking.
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