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  #1  
Old 11-08-2021, 05:03 AM
TJHeller TJHeller is offline
 
Join Date: May 2021
Location: Midland TX
Posts: 3
Default Elevator trim servo locked up?

My plane has been sitting for almost 2 months while an avionics upgrade was taking place. Upon arrival to pick it up it was discovered that the elevator trim wasnít functioning. Thereís power at the panel, switch, and motor, and it worked 2 months ago. An internet search revealed its not uncommon for servos to just freeze, and Iím thinking this is what happened. Anyone have similar experience?
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  #2  
Old 11-08-2021, 08:10 AM
lr172 lr172 is offline
 
Join Date: Oct 2013
Location: Schaumburg, IL
Posts: 7,754
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That ray allen servo/motor is used in a LOT of planes and doesn't seem like they fail or stick often. I would be looking at binding in either of the two cables or possibly the aluminum transfer components being stuck. They sit on the plate near the servo and they transfer the force from the servo to the two cables. Pull the Emp cover and get eyes on the components under the turtle deck.

Larry
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  #3  
Old 11-08-2021, 08:18 AM
Bgill Bgill is offline
 
Join Date: Sep 2017
Location: Douglas, GA
Posts: 119
Default

Never had an issue with the trim servo - itself. My RV14 had a nonfunctional trim one day and it turned out to be the micro molex plug supplied (since replaced). Like Walt indicated, I have had TT servo completely lock up and had to send back.
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RV-14A 140466 N384RV - Phase 1 Complete
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  #4  
Old 11-08-2021, 09:09 AM
Carl Froehlich's Avatar
Carl Froehlich Carl Froehlich is offline
 
Join Date: Dec 2007
Location: Dogwood Airpark (VA42)
Posts: 3,944
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Quote:
Originally Posted by Bgill View Post
Never had an issue with the trim servo - itself. My RV14 had a nonfunctional trim one day and it turned out to be the micro molex plug supplied (since replaced). Like Walt indicated, I have had TT servo completely lock up and had to send back.
Donít ever use the supplied micro molex plugs provided in the wiring kit.

Carl
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  #5  
Old 11-08-2021, 09:19 AM
BoydBirchler BoydBirchler is offline
 
Join Date: Jul 2020
Location: Indianapolis
Posts: 201
Default

We had an issue with the trim servo on my wife's plane. After many instances and hours of searching, it turned out to be a defective/intermittent micro switch in the stick's trim switch.
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  #6  
Old 11-08-2021, 09:36 AM
PilotjohnS PilotjohnS is offline
 
Join Date: Jan 2016
Location: Southwest, USA
Posts: 2,535
Default just me

Quote:
Originally Posted by BoydBirchler View Post
We had an issue with the trim servo on my wife's plane. After many instances and hours of searching, it turned out to be a defective/intermittent micro switch in the stick's trim switch.
Just for kicks, I originally planned to only have the pilot stick with trim buttons, but this thought crossed my mind that if a trim switch failed, i would be up a creek without a paddle. So i added trim buttons to the copilot's stick too.
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WARNING! Information presented in this post is my opinion. All users of info have sole responsibility for determining accuracy or suitability for their use.

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  #7  
Old 11-08-2021, 01:49 PM
BobTurner BobTurner is offline
 
Join Date: Dec 2011
Location: Livermore, CA
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Quote:
Originally Posted by PilotjohnS View Post
Just for kicks, I originally planned to only have the pilot stick with trim buttons, but this thought crossed my mind that if a trim switch failed, i would be up a creek without a paddle. So i added trim buttons to the copilot's stick too.
Hopefully you arranged the wiring so pushing trim up while the passenger is (inadvertently) pushing trim down wonít trip the CB or blow a fuse. Likewise, I have heard of serious trim excursions when the passenger rested a magazine against the trim button. Something to think about.
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  #8  
Old 11-08-2021, 01:53 PM
N427EF N427EF is offline
 
Join Date: Oct 2005
Posts: 1,697
Default TCW Technologies

https://www.tcwtech.com/product/safe...v=7516fd43adaa

This was my answer to the frequent reports of stuck trim motors.
It comes with a few additional features besides trim reverse etc.

A trim motor malfunction seems less of an issue in the spring biased aileron installation but a rather difficult problem to handle on the elevator.

A passenger trim disconnect switch is also a good idea, installed in my 10 as well
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  #9  
Old 11-08-2021, 01:58 PM
lr172 lr172 is offline
 
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Location: Schaumburg, IL
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Quote:
Originally Posted by BobTurner View Post
Hopefully you arranged the wiring so pushing trim up while the passenger is (inadvertently) pushing trim down won’t trip the CB or blow a fuse. Likewise, I have heard of serious trim excursions when the passenger rested a magazine against the trim button. Something to think about.
These were my concerns as well, so have no copilot stick trim. However, I also was worried about the stick button failing and the 10 is a bear without up trim on landing. So I put a small DPDT (Mom-off-Mom) switch on the panel as a backup. No real risk of a passenger activating it, though still can be used by someone flying right seat.

Larry
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Last edited by lr172 : 11-08-2021 at 02:01 PM.
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  #10  
Old 11-08-2021, 02:23 PM
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Mike S Mike S is offline
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Join Date: Sep 2005
Location: Dayton Airpark, NV A34
Posts: 16,558
Default Welcome to VAF

Jason, welcome to VAF.

Have you tried to apply power directly at the servo----a 9v battery will be enough to make the servo move if it will.
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VAF 909

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Flying as of 12/4/2010

Phase 1 done, 2/4/2011

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"Flying the airplane is more important than radioing your plight to a person on the ground incapable of understanding or doing anything about it."
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