Electric Trim Adjustment

Shempinator III

Hi everyone,

The electric trim in my PA28R-201T functions but half the time it slips. The spindle turns but the clutch will grab and slip off and on. I tightened the nut to the pecs @ .002 clearance. I'm not sure what more I can do to fix this.

Thanks for any help.

Todd

griff390

https://piperowner.org/talk/discussion/157068/electric-trim-adjustment

Todd:

Some things to check;

1. The clutch is a friction type. Check that the clutch is not worn out.
2. Over time the groove in the pulleys wear. As they wear, the groove deepens, and can pinch the cable.
3. Check that all the pulleys associated with the trim system are turning freely and not locked up. A locked pulley can cause #2 above.
4. Clean and lube the jack screw connected to the stabilator trim tab.

In my experience, #4 is generally the most common culprit.

It's easy to confirm that you've fixed the issue. On the ground, you should be able to manually spin your trim wheel with little resistance. If it's tough for you, it's going to be tough for the trim motor, because the electric trim motor must overcome the same resistance you are feeling.

empannin

Agree with Jim on this and also agree #4 is the first place I would check. Be careful on the lubrication applied. Needs to be low resistance including at cold temps. The material in the service manual does not exist any more...

Also make sure the clutch is contamination free

Tokirbymd

My old six was like this- took a lot of looking and comparing to my A&Ps lance but eventually figured out the trim idler pulley was wrapped in the wrong direction. Once we rerouted was perfect so I would look at that carefully just in case.

Shempinator III

Thank you for all the advice. I will let everyone know my findings. Any suggestions on a Brand of lubrication?

Thanks

Shempinator III

Also, the trim is a little stiff when turning manually. I am not sure if it is too stiff as I haven't been able to compare with a normally functioning one.

Seneca38173

Todd,

Piper recommends Aeroshell 7 in the factory course for the pitch trim jack screw, which is a synthetic upgrade to the original MS number. Some A&Ps also use Aeroshell 5, which is not recommended due to reduced temperature range.

Before you remove the tail covers to clean and lube the screw, you might try manually rolling the trim wheel full forward and full backward 3-4 times. It's probably about 10 full flicks of the wrist each way. This may redistribute the grease, and you'll know it's happening as the "back and forths," gradually become smoother and show less binding.

The other "easy check," is the cable tension. Unless the cable is adjusted pretty close to 10 lbs of tension, the capstan in the electric trim servo will be unable to develop the traction necessary to drive the jack screw without slipping. There is(are) turnbuckle(s) in the tail that allow tension adjustment. They are supposed to be checked and adjusted every annual, but it seems like this occurs infrequently, since the job can only be accomplished by an A&P who is young, skinny, flexible, and highly motivated. LOL

BTW, our recently retired president (Scott) wrote an excellent article a few years back about troubleshooting and lubricating the trim system. You'll find it in the Pipers Magazine, and it may have been delivered in two parts.

Good Luck,

Bob

Shempinator III

Thanks so much Bob, I'm looking forward to getting into this and a know many of my passengers are too if you know what I mean 🤣

Shempinator III

I found the article (Oct 2016) but am not sure how to open it. I get the cover up but am not sure how to access the article.

Thanks

Seneca38173

OMG, that was eight years ago. Time "flies!"

The POS site makes me re-enter my username password, but otherwise the article comes up fine. Scott made a lot of great points in that article.

Pipers Magazine October 2016 | Piper Owner Society

Shempinator III

Still can't get past the cover. I'll mess with it later.

Thanks Bob

P.S. I did find this in my search!

Pitch Trim Manual.pdf

Shempinator III

Good morning Bob, I am still having difficulties accessing the magazine. I called tech support and they weren't any help. After selecting the magazine and then it asked to log in again it takes me back to the main page and the process starts all over again.

Shempinator III

Scratch that last post. I am now successful on accessing the magazine. Thanks

Seneca38173

Right. I'm puzzled as to why once you're logged in to the forum, you can't go directly to the magazine without a second login. Seems like the context should be retained between the two domains. Maybe Mike can answer this?

jonesdi

I'm trying to recreate the issue over here, but haven't been successful. But, could you try logging into the website first at www.piperowner.org, then go over to the forum and see if you are logged in? Let us know if that works.

Shempinator III

My issue was my browser "Safari" was too old and wouldn't support the magazine link. I logged out and then reopened the Piper owner site with Google "Chrome" and it worked. And, I didn't have to log in twice.

krelsey

I had this same problem on my first Arrow. I was able to fix this issue by replacing the cork clutch gasket and then gapping to .002-.003". Also, if you decide to mist/fog ACF-50 in the back of the fuselage make sure to wrap a plastic gag around the system before spraying.

Shempinator III

Thanks for the input Krelsey.

Update:

I cleaned and lubed the screw in the rear of the aircraft. After that, no change.

I decided to check the solenoid slug that activates when the switch is hit. The slug drops down and engages the clutch. It didn't appear to drop much so while I had the switch on for up trim, I took a screw driver and pushed down on the top of the slug through a hole on the top of the trim box. The slug popped down as if it was stuck and the trim turned and worked like a champ.

I did this several times. Something is causing the slug to stick. So, I will remove the trim box and find out what the problem is. More later.

Thanks