Trim Wheel Moves Nose Nown In Flight

[lamont337]

Gents, I've searched and gone through a few old threads about trim being stuck or difficult to move but I have the opposite problem. After trimming for level flight I can occasionally watch the trim wheel rotate slowly to a nose down position. The picture below was revised in '66 but I have a '62. My trim assembly does NOT have the 4 nuts to loosen or the two vertical bolts that could be used to tighten the chain. The box is riveted together as one assembly with no obvious adjustment possible. The trim jack screw assembly in the tail was rebuilt by Lasar a few years ago and I'm not sure what else to check. Any advice is appreciated.

Here's one like mine on Ebay: https://www.ebay.com/i/142987801229?chn=ps&norover=1&mkevt=1&mkrid=711-117182-37290-0&mkcid=2&itemid=142987801229&targetid=888709244052&device=c&mktype=pla&googleloc=9016915&poi=&campaignid=9426322072&mkgroupid=92907997622&rlsatarget=pla-888709244052&abcId=1141016&merchantid=109942766&gclid=Cj0KCQjw-_j1BRDkARIsAJcfmTEaArjSv6EOodQCbl-G13VkGz34Dku7hXeMPnFWQPmZHvFCAUGYBEkaArSaEALw_wcB

And this one is more like the picture: https://www.ebay.com/i/274312169564?chn=ps&norover=1&mkevt=1&mkrid=711-117182-37290-0&mkcid=2&itemid=274312169564&targetid=882497019982&device=c&mktype=pla&googleloc=9016915&poi=&campaignid=9248481111&mkgroupid=93538209803&rlsatarget=pla-882497019982&abcId=1141156&merchantid=138359445&gclid=Cj0KCQjw-_j1BRDkARIsAJcfmTEsDtjP10Piip0c9IOwNxPT5QOUzX71MVk7ki4GE55FXUblIiAzW5UaAvwVEALw_wcB

[Guest]

The foot note on the left says to adjust the eccentric bushing to tighten the chain.

Clarence

[lamont337]

7 minutes ago, M20Doc said:

The foot note on the left says to adjust the eccentric bushing to tighten the chain.

Clarence

 

I did see that and should have mentioned it, but upon visual inspection the eccentric is riveted in place. No six screws around shaft. Suppose we could drill it out, rotate, drill a new hole and rivet again but it's gonna be really hard to get it in the right place on the first try. I'll try to get some pictures with the cover off when I'm at the airport tomorrow.

[N201MKTurbo]

The later models had a spring loaded friction device to keep it from doing that. Mine had the nut plate for it, but the bolt spring and friction pad were missing. I made a new one and the trim wheel behaves much better now. 

[takair]

You need anti-lube.  A slurry of peanut-butter, old grease and dust..  

[0TreeLemur]

6 hours ago, takair said:

You need anti-lube.  A slurry of peanut-butter, old grease and dust..  

Being oil based, peanut butter and old grease is the wrong base.  I'd use some  3M fabric adhesive as the base, with some tank sealant and very fine sand.   Apply quickly.

[N201MKTurbo]

6 hours ago, takair said:

You need anti-lube.  A slurry of peanut-butter, old grease and dust..  

That’s what I cleaned off my chain when I rebuilt my trim wheel. That’s when it started slipping nose down. You might have something there?

[David Lloyd]

Was why the dog kept licking the trim wheel.

[cctsurf]

I had a similar problem on my '62.  We added friction to the wheel and no longer have this problem.

[mike20papa]

My first try - after I had read up on all the maintenance material - would be to tighten the chain.