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Trim wheel issue


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Looking for some input.  I have a trim issue that I thought was in the u-joints that were totally slopped out.  Had my mechanic swap them out and it is better but still not smooth.  I disconnect the linkage and the trim wheel moves from lock to lock with gentle friction and seems fine.  I am guessing the problem is in the tail screw.  Are those rebuildable or are they throw away when bad?  Also how does one remove the rear assembly with out total disassembly of tail.  my AP is talking about removing the tail.  I don't see why that is needed but I might be wrong.  Wouldn't be the first time.

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I can't absolutely speak to the necessity of removing the tail, but on Mooneys as far as I understand, removing it is not as big a deal as one might assume.  A search of Mooneyspace may get you some ideas.  Here's a thread to get you going: 

 

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1 minute ago, Vance Harral said:

It's not necessary to remove the tail, the thread cctsuff lined to above has details.  You can rebuild it yourself using parts from LASAR, but frankly it's easier and less anxiety to just send the whole thing to LASAR and let them do it for you.

I can rebuild it faster than packing it.

 

1 hour ago, Dream to fly said:

Looking for some input.  I have a trim issue that I thought was in the u-joints that were totally slopped out.  Had my mechanic swap them out and it is better but still not smooth.  I disconnect the linkage and the trim wheel moves from lock to lock with gentle friction and seems fine.  I am guessing the problem is in the tail screw.  Are those rebuildable or are they throw away when bad?  Also how does one remove the rear assembly with out total disassembly of tail.  my AP is talking about removing the tail.  I don't see why that is needed but I might be wrong.  Wouldn't be the first time.

There are many threads about this. There are very detailed threads about removing it, disassembling it, cleaning it, re-greasing it.

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Just now, N201MKTurbo said:

There are very detailed threads about removing it, disassembling it, cleaning it, re-greasing it.

That's the easy part, and yes it hardly takes any time at all.

The catch is the shims that must be inserted on reassembly to make the whole assembly tight enough, but not too tight.  LASAR will send you a bunch of shims to select from, but it's a guess at best, and there may be some back-and-forth exchange to get the right size.  More importantly, if you haven't done it before (raises hand), you don't really know exactly what you're looking for in terms of fit.  In the threads mentioned above, there are stories of people who discovered only on reassembly that they selected shims that felt right before installation, but wound up binding the trim mechanism on installation.

I have no doubt N201MKTurbo knows all this and can do the job professionally, but I didn't have enough faith in myself or my local shop to get it just right on the first try.

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One other common thing to look for...

The trim tube can rub on several bulkheads it passes through.  There is an sb for this.  It will cause friction and actually start cutting through the tube.  Theres a limit in the sb for cut depth before needing a new (expensive) tube.  There are sacrificial (phenolic) blocks that hold the tube just above the hole through each bulkhead and the sb mentions some tape that can be applied to the tube.

Its probably the thing the other guys are saying, I’d just make sure it’s not the tube rubbing because that can definitely happen too.

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You didn’t really describe the problem, so it is hard to help. When you rotate the trim wheel is there sort of a periodic chatter or shudder as you rotate the wheel? Does it happen in the air or just on the ground? Does it happen more in one direction than the other? Do you have an autopilot with a trim servo?

On the ground, moving the trim will cause the controls to move forward and back due to the trim assist bungees. Mooneys often have some friction in the control shaft bearing where it goes through panel causing stickiness or hesitancy for small movements. This can be transmitted to the trim system. Try holding the yoke so it cannot move while rotating the trim and see the effect on the trim system.

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Joe,

Looks like you got all the details available for that gear box...   Go MS!

Be on the lookout for old grease...  the old grease turns to rocks and makes things difficult to move...

Sometimes it is the grease on the Jack screw...  but the grease inside the gear box might be original...

+1 for keeping track of the shims...

PP thoughts only, not a mechanic...

Best regards,

-a-

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