Elevator Trim position sensor

[warrenehc]

Hello,

I just had avionics work done and my elevator trim position sensor is not normal.

When going the full range of the trim it only goes done to the top of the TO setting and all the way to the full up position.

Where is the sensor located to adjust back to show full trim travel 

Edited April 22 by warrenehc

[N201MKTurbo]

1 hour ago, warrenehc said:

Hello,

I just had avionics work done and my elevator trim position sensor is not normal.

When going the full range of the trim it only goes done to the top of the TO setting and all the way to the full up position.

Where is the sensor located to adjust back to show full trim travel 

I assume they were working on the trim servo. They probably disconnected the trim torque tube and didn’t put it back together the same as they took it apart. 

[warrenehc]

6 hours ago, N201MKTurbo said:

I assume they were working on the trim servo. They probably disconnected the trim torque tube and didn’t put it back together the same as they took it apart. 

Thanks Rich.

To be more specific, I feel that I am running the trim through its full range. 10-15 full rolls of the trim. When rolling full up and full down the elevator appears to be moving its full range from the outside while watching it move.

The panel was replaced in the upgrade. Do you think by chance just the trim indicator cable is not working properly. Indicators were located in the same position as original panel.

[N201MKTurbo]

Do you have mechanical or electronic trim indicators?

[warrenehc]

1 hour ago, N201MKTurbo said:

Do you have mechanical or electronic trim indicators?

Electronic. 1990 M20M

[N201MKTurbo]

9 minutes ago, warrenehc said:

Electronic. 1990 M20M

Sorry, my advice was considering the mechanical indicators. I’m not familiar with the electronic displays. 

[warrenehc]

9 minutes ago, N201MKTurbo said:

Sorry, my advice was considering the mechanical indicators. I’m not familiar with the electronic displays. 

Not a problem. Thank you for reaching out.

[IvanP]

The electronic indictors have a small potentiometer that can be adjusted to show the correct travel. Check page 27-40-02 of the IPC.

This assembly is in the tail of the plane so if only avionics were worked on it should not have been be disturbed, but it may be worth checking. It is also possible that the indicator itself is malfunctioning. The indicator is one box for both trim and flap indication. Check the plug on the back if it is secured. When you are running through the trim range, does the indicator stop changing while the trim is still running?  

[Rick Junkin]

On 4/21/2025 at 10:20 PM, warrenehc said:

Hello,

I just had avionics work done and my elevator trim position sensor is not normal.

When going the full range of the trim it only goes done to the top of the TO setting and all the way to the full up position.

Where is the sensor located to adjust back to show full trim travel 

@warrenehc The procedure for adjusting the electronic trim indicator is in the M20M service & maintenance manual. It's a somewhat laborious and iterative process best done with two people. You'll need to drop the belly panel to get to the trim potentiometer for the "down" adjustment, and pull the indicator out of the panel and open it up for the "up" adjustment. Here's a screenshot of the pages from the SMM with the instructions on how to go about it. The info specific to the trim indicator are on the second page, paragraph #2.