Rudder trim

[Patrick Horan]

Hey guys, when I started up the plane, I tested the rudder trim and I didn't get any indication it was moving. My mechanic came to look at it and he confirmed thst the rudder trim wasnt actually moving. He went to the after service bay and saw that the micro switch in the back was dirty and he cleaned it a bit. Now my rudder is working but the indicator still shows center (it doesn't move). I believe it has something to do with the pentometer but I'm not exactly sure or where that is

Edited May 20 by Patrick Horan

[PilotX]

 

27-40-02

[IvanP]

It is by the rudder trim motor in the rear bay - #6 on the diagram.

Part No. WA2G05GS-502UA

 

M20M-27-40-03.pdf

[Patrick Horan]

19 minutes ago, IvanP said:

It is by the rudder trim motor in the rear bay - #6 on the diagram.

Part No. WA2G05GS-502UA

 

M20M-27-40-03.pdf 102.22 kB · 0 downloads

Thank you

[Patrick Horan]

20 minutes ago, IvanP said:

It is by the rudder trim motor in the rear bay - #6 on the diagram.

Part No. WA2G05GS-502UA

 

M20M-27-40-03.pdf 102.22 kB · 0 downloads

If that part is bad, where would the best place to get it? Salvage?

[Rick Junkin]

1 hour ago, Patrick Horan said:

If that part is bad, where would the best place to get it? Salvage?

The alternate part, RV6NAYSD502A, is available from Mouser. I replaced my stab trim potentiometer last year and it's the same part. About $40 with shipping. Follow the wires from the potentiometer back to find the barrel connector and remove the whole assembly (potentiometer and wiring pigtail) from the airplane for an easy soldering job.

https://www.mouser.com/ProductDetail/882-RV6NAYSD502A

You might want to loosen the arm attached to the potentiometer and try to rotate the potentiometer by hand to make sure that's really the problem. You're getting an indication on the trim indicator, which means power is getting through the potentiometer, so it's possible it's either frozen or just not being turned by the arm.

 

[IvanP]

1 hour ago, Patrick Horan said:

If that part is bad, where would the best place to get it? Salvage?

It is Allen Bradley 5k ohm pot. I found one on E-bay last year when I needed replacement. I believe that the same pot is also used for flaps and trim indicators. I bet that Mouser or other electronic parts suppliers will have equivalent part if you cannot locate the original part. 

Also, I made an error in my original post - the part No is WA2G056S-502UA (i read G instead of 6 in the catalog - my eyes are not as good as they used to be). 

E-bay link: https://www.ebay.com/itm/153892538415?_skw=WA2G05GS502UA&itmmeta=01JVQJY1QJDS9WBMW5P4PFPK4N&hash=item23d4b5c82f:g:eL8AAOSw4A9ejyQe&itmprp=enc%3AAQAKAAAA0FkggFvd1GGDu0w3yXCmi1d3mW9PlXdF0higTxjaCdMxGMVyen0tCZte%2BOYWguMbGLEGhGE1tq0cxD69hu48XKx35mfIhr3qkr1v77%2FQlveLQLMqHzCpsxxvBtUrGk0b5bgthYECRUHImYVV%2Bwkx8gS5bQvRIvOOmD%2BduDeb8wIljgMhpeKGE%2FpGnFUsea%2B7%2BeDVl3gUl5cPWJD%2BGD6jxR8tK4RxZYp2SaIiuMp3Fw1yrz%2B%2FfMDVJQyJ1U3PdkWakdWUev1J4Z4Tcp3g4lTOBW0%3D|tkp%3ABk9SR_ib-PLdZQ 

[Patrick Horan]

Hey guys, I just checked the back. It looks like the potentiometer is disconnected from that Allen screw.  Also, the image is flipped

[N201MKTurbo]

Looks like an easy fix. Just make sure you get them synced. I would adjust the motor for neutral trim, then spin the pot so it indicates neutral trim and hook them back together.

[IvanP]

54 minutes ago, N201MKTurbo said:

Looks like an easy fix. Just make sure you get them synced. I would adjust the motor for neutral trim, then spin the pot so it indicates neutral trim and hook them back together.

Starting in full deflection to either side may be easier. I am not sure how easy it is to eyeball the "neutral" position of the trim mechanism. Two person job - one in cockpit and one under the plane. The picture makes it look like the pot shaft is not aligned well with the other piece. Did the screw just get lose or is the shaft broken? Maybe it is just the picture, but I would check the setup for excessive slop in it.    

[Patrick Horan]

35 minutes ago, IvanP said:

Starting in full deflection to either side may be easier. I am not sure how easy it is to eyeball the "neutral" position of the trim mechanism. Two person job - one in cockpit and one under the plane. The picture makes it look like the pot shaft is not aligned well with the other piece. Did the screw just get lose or is the shaft broken? Maybe it is just the picture, but I would check the setup for excessive slop in it.    

That's what I couldn't figure out. It looks like the pententiometer didn't want to go in any further. The shaft might have broken. But I really don't know

[Patrick Horan]

50 minutes ago, IvanP said:

Starting in full deflection to either side may be easier. I am not sure how easy it is to eyeball the "neutral" position of the trim mechanism. Two person job - one in cockpit and one under the plane. The picture makes it look like the pot shaft is not aligned well with the other piece. Did the screw just get lose or is the shaft broken? Maybe it is just the picture, but I would check the setup for excessive slop in it.    

Looking at the other ones for sale. The ones for sale all look like they have a longer shaft

[IvanP]

YEs, the shaft is about 1in long if I recall correctly, but that is not necessarily the problem. If you drop the belly pan, you will have better access to the mechanism to see if anything is misaligned or broken. It seems that there is some blue Locktite on the set screw. Try to move it and see if that is the issue or not. Try to run the trim both ways with the belly pan off and observe.

[Patrick Horan]

29 minutes ago, IvanP said:

YEs, the shaft is about 1in long if I recall correctly, but that is not necessarily the problem. If you drop the belly pan, you will have better access to the mechanism to see if anything is misaligned or broken. It seems that there is some blue Locktite on the set screw. Try to move it and see if that is the issue or not. Try to run the trim both ways with the belly pan off and observe.

I didn't realize the belly pan came come off that far.

[IvanP]

The belly pan ends at the bulkhead, but dropping it may give you a it better view of the mechanism. I had to do it to access the limit switches for rudder trim motor. As everything in Mooney, access is a b%$#@. 

[Patrick Horan]

3 hours ago, IvanP said:

The belly pan ends at the bulkhead, but dropping it may give you a it better view of the mechanism. I had to do it to access the limit switches for rudder trim motor. As everything in Mooney, access is a b%$#@. 

Thank you for the help!

[dkkim73]

17 hours ago, Patrick Horan said:

Hey guys, I just checked the back. It looks like the potentiometer is disconnected from that Allen screw.  Also, the image is flipped

It looks as though that brass colored screw is loose...? Ie rendering those parts father away from each other? 

[Patrick Horan]

21 hours ago, dkkim73 said:

It looks as though that brass colored screw is loose...? Ie rendering those parts father away from each other? 

Its was pretty tight when I tried to losen it, probably because of the lock tight. Ill look at it soon