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I was flying today and all was good till I was going to trim to land.  The trim wheel got super stiff to turn to pitch up.  Turns easier to pitch down.  Is there a friction lock I don't know about?   I have removed the belly pan and see nothing bent damaged or dirty to be causing this.  But I might not be looking at all the possibilities. 

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Has the jack screw been cleaned and lubed recently?  That is the most important place to look.

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Look in the tail, not in the belly. Check the jack screw. It can get pretty caked up with very dirty/stiff grease like shit.

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Jackscrew is is most likely, but to answer yout question there is a friction lock, it's #14, access is from in the cabin

 

image.jpeg.65cf1fb78a4ce57c27a78811f075a256.jpeg

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1 hour ago, gsxrpilot said:

Look in the tail, not in the belly. Check the jack screw. It can get pretty caked up with very dirty/stiff grease like shit.

I think it is the bearing that the tail tilts on.  The threads are clean.  and the u-joints are lubed and free.   twisting the tube by hands seems easy.  I found the friction lock and I backed it off no difference.  It almost seems like pitch up and it is binding.  I just don't see where.  Gonna have the wife turn the wheel while I look underneath and in the tail.  Kinda weird how it was fine then it wasn't.  That is what made me think I friction locked it but no luck.

Just got a crazy idea.  If I go into the battery area and separate the control rod at one of the accessible joints I could prove full movement of the tail and Isolate the controls  Do those roll pins remove easily?

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Yes, they are pretty easy to remove and would be a good way to isolate the problem.  You should be able to twist the tube using just your hand. 

The easiest joint would be in the tail just aft of the big access panel on the pilot's side.  You'll need 2 new small cotter pins to reattach it. 

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Just now, LANCECASPER said:

It wouldn't hurt to read these over: 

 

Thanks figures I was not using the right words in the search.....

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1) a stuck trim has ended the life of a once good Mooney. You have the thread there...

2) It is better to find out what is not working while still on the ground...

3) cleaning and lubing the parts of the control system is good.

4) disconnecting parts of the control system is Best done with a mechanic on your team.

5) there are a couple of known trim stickiness issues. One requires electric trim.  The other is old aged grease.  The system is so simple, chain, gear, u-joints, bearings, gearbox, threaded screw...

6) remember all the things that make need for trim changes... power setting and flap deployment. If the trim sticks in flight. It is going to make theses changes difficult.

7) going without trim can be like holding 50 pounds or so in each hand, while flying the plane... kind of tiring The you run out of muscle strength...

8) there is an old leather(?) friction lock up by the handwheel. At one end.  The gear box with the trim screw and bearings are at the back... thank RLC for supplying the drawings...

How is that for logic for not flying without the trim working properly?

Best regards,

-a-

 

Edited by carusoam

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I doubt that the movement of the tail is your issue, it swings through a very small arc on two chrome plated bushings.  

You could run the trim to the full up position then cut a piece of 2X4 to fit between the fuselage and the tail section. Remove the tail trim link allowing the tail to rest on the 2X4.  Now you can move the jack screw to see if it is binding.  Then your idea of separating the trim drive shaft will allow you to check the drive system and locate the fault.

I would disassemble the drive tubes from the forward trim gear box.  Once you isolate and repair the trouble you will need a travel board to rig the system.

Clarence

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The old stuff that looks like grease.  Is something that has hardened into a pasty glue.  Clean Chain and all the little U joints.   Lube the jack screw.  run up and down several times.   Check the holes where the driveline goes through the plane.  I even cleaned and lubed them. 

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Check the indicator cable. Mine was binding and causing the "sticky" problem.

Sent from my XT1585 using Tapatalk

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Had way too many honey dos to do today so I only verified the problem.  I separated the control rod in the battery section and the trim wheel turns freely.  The other side that goes to the tail is just about impossible to turn.  I removed the side inspection covers but there is boot or cone around the rod that looks like it was made before mountains were formed.  I'll have to figure out how to replace that and then get the jack screw out and cleaned.  What I can see is just hard crusty grease.  One would think there should be a grease fitting going to that gear set.  Tomorrow is another day.

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Rubber boots were made out of fabric back in the day...  sounds like some of the grease may be as old as your plane.

Somebody recently posted pictures of the screw and all the insides of the box it mounts in...

Cleaning out all the grease from the roller bearings(?) that are in there worked the necessary magic.

Best regards,

-a-

Edited by carusoam

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+2 on the idea of having the need for a travel board now and you will have to jack the airplane level to set it correctly when you get done cleaning it. Be careful of the very thin shims inside the housing that set the bearing end play, Make a drawing of how they go in. Once you get the stabilizer throw set you can check and reset the  bungee deflection of the elevators. All the correct throws are in the TCDS by serial number of the airplane. When you need to adjust the bungees you loosen the jamb nut on the forward end of the bungee (use a crows foot and an extension) and turn the rear part in or out to get the correct deflection. Both elevators should be done equal at the same time. Its not hard , it just takes the correct equipment and time.

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I had this same problem in my j. It was the pillow bearing under the trim servo in the tailcone. A shot of triflow cured it.

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Well previous repairs caused it.  An old piece of shop rag was caught in the treads.  My guess is the previous supper hero used a rag to cover the rubber boot that was deteriorating and when the boot failed the rag laid on the threads and got pulled in.  I've cleaned it and it works again at annual I will have to get the tail removed and the boot replaced.  For now I used a shock boot that is made of neoprene and split it and then re-sealed it to keep dirt out.  I still have drag on the system but it moves the full range again.  I'll have to address the rest of this in the fall/winter.

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