Servo Motor for electric trim

[FBCK]

My auto pilot is 100% (KFC200, 1981 M20K), but my electic trim on the yoke is very slow or when turned on via the trim switch does not move, I believe the servo motor is dead or soon to be.  Does anybody have any experience with this and what should I expect.

[larryb]

How is the effort on manual trim wheel? I recently had an issue with stiff trim, the electric could hardly move it. In my case, the bearing was sticking. It is right behind the motor, which is in the tailcone aft of the battery. I have an 84 J. The mechanic used some tri-flow spray on it and it was fine.

 

Larry

 

[FBCK]

I had posted the problem back some time ago as well, when cold (-20c) the wheel was very stiff but in warm weather it is fine.  I did lube the hindge in the tail cone as it was very dry but it had little effect.

[John Pleisse]

That KFC 200 servo is about $1500 rebuilt/exch. It should operate freely at all times at about the same rate your flaps deploy and retract. Also, sometimes it could just be the chain or another periphial getting stuck, etc.

[FBCK]

Would you know who best to go to or to do the rebuild.

[John Pleisse]

Quote: FBCK

Would you know who best to go to or to do the rebuild.

[M20JFlyer]

Fellow Mooney Space pilots:

On March 2 of 2012 I started a thred on the King/Bendix/Honeywell Autopilot Servo Trim Motor Failure and repair.

At that time I was getting difficult NEWS to digest on the cost ($$$ mega bucks) to repair the Pittman Motor that drives the Servo.

If the AP in question is a King ..it is possible the TRIM SERVO motor was built by Pittman . I had my motor NOT THE SERVO electronics repaired and all is working fine  46 hours since motor repair.

If interested give me a PM to Plyons820@yahoo.com.

M20 J N9135W @ KAXH Houston TX  (

[FBCK]

I'm having an avionic shop take a look on Monday, so I will let you know what he finds and what he suggests.

[FBCK]

The avionics shop tells me it is the trim servo motor (part number 065-0029-28), they got it moving once but prehaps thats it.  So I'm on the hunt for a new one, there is a shop in town here that can rebiuld it, but I thought I would try from the group here for suggestions.

[jetdriven]

Call Autopilots Central in Tulsa, and ask if they can overhaul it for you.  Have your shop do the R&R. They can probably do it better than King if they have the capability.

[Zulee]

Sarasota avionics repaired the servo in my right wing, said dust from the brushes eventually build up and cause the motor to stick.

[flyboy0681]

Sarasota does a good job. The head unit from my KAP 150 went dark two weeks ago and they took care of the repairs for $325. The problem turned out to be a transistor.

[E Dieckman]

Amen to the bearing in the tail cone behind the electric trim motor. I have a 1981 M20k the electric trim was really hard to turn. I was thinking it was the jack screw also. After we disconnected the trim rod between the jack screw and the electric motor and disconnected between trim wheel and electric motor we found the bearing needed lube. Shot it with some LPV and it worked like new. I couldn’t believe it. 

[carusoam]

Welcome aboard E D.

Great pirep!

Awesome first post!

Best regards,

-a-

[PT20J]

On 1/2/2020 at 4:40 PM, E Dieckman said:

Amen to the bearing in the tail cone behind the electric trim motor. I have a 1981 M20k the electric trim was really hard to turn. I was thinking it was the jack screw also. After we disconnected the trim rod between the jack screw and the electric motor and disconnected between trim wheel and electric motor we found the bearing needed lube. Shot it with some LPV and it worked like new. I couldn’t believe it. 

The carrier bearing is called out in the service manual for yearly lube, but almost no one ever does it. The LPV will temporarily get things moving, but you really need to take it loose from the shaft clean it and lube it with grease per the service manual. It's fairly heavily loaded by the trim servo chain and needs grease.

Skip

[rcwagner]

I recently had an STEC 55X installed in my 1978 M20J.  The Western Aviation (Spokane) technician mistakenly removed my manual electric trim system even though I did not get the automatic trim option on the STEC.  I have all the parts, but am debating whether to reinstall the electric trim.  I am considering just using the manual trim wheel and keeping the aircraft simpler from a maintenance stand point.  Do most Mooney's have manual electric trim on the yoke?

[N201MKTurbo]

2 minutes ago, rcwagner said:

I recently had an STEC 55X installed in my 1978 M20J.  The Western Aviation (Spokane) technician mistakenly removed my manual electric trim system even though I did not get the automatic trim option on the STEC.  I have all the parts, but am debating whether to reinstall the electric trim.  I am considering just using the manual trim wheel and keeping the aircraft simpler from a maintenance stand point.  Do most Mooney's have manual electric trim on the yoke?

There is a problem that would need to be resolved. Your plane probably had a Century electric trim. The autopilot and trim disconnect operate through a common disconnect relay. It would take some custom wiring or a custom relay to get it work together. Being a safety critical item (runaway trim and all that) the field approval process might be onerous.

[rcwagner]

I was told by a Mooney Service Center that the manual electric trim and the original Century IIB single axis autopilot ran independently from one another.  I had a Century IIB single access autopilot in the plane before the STEC install.  If I recall correctly, the CIIB didn't have an autopilot disconnect, just an on-off switch.  The electric trim also had its own on-off switch.