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Jackscrew


201Steve

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Howdy folks,

I have some issues with the trim system on my '77 J. The wheel gets very tight and hard to turn, right around the takeoff setting. I've been dealing with it for a little bit, but I know it's stressing the electric trim and it's a real nusance when trying to trim on the fly in the critical phases of flight. My Mooney mechanic traced it to the jack screw and the price for a new one is like $1,700. Any suggestions where I could perhaps source a used one? I've only had it for about 7 months so I'm not familiar with what outfits might be the Go-To on something like this. Thanks for any feedback!

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Before replacing it, just open it up and remove all of the old grease. It's probably hard and chunky. Refill with fresh grease. 

There should be a thread here somewhere about doing this, and maybe something on Maxwell's site, too. If your A&P is unsure, visit an MSC.

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There’s a guy on Mooneyspace with a used one, he goes by 201Steve!  All kidding aside as others have said it likely needs disassembly cleaning and some new grease.

Clarence

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My mechanic is a MSC and did re-grease it, said that he'd never really seen one act the way mine is. You can stick your hand in there and feel that the threads are almost "sharp" compared to a normally functioning one where the threads on the screw are more smooth feeling. 

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The thread you want to read is here:

My guess is that when your mechanic "re-greased" the jack screw, he just slopped some fresh on the jack screw shaft, through the opening in the empennage.  That's fine for regular maintenance, but once every 10 or 20 or 50 years, you've gotta pull that thing out, disassemble, and clean/re-grease it.  Among other things, it provides an opportunity to check the bearings which the shaft goes through.

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Just now, Vance Harral said:

The thread you want to read is here:

My guess is that when your mechanic "re-greased" the jack screw, he just slopped some fresh on the jack screw shaft, through the opening in the empennage.  That's fine for regular maintenance, but once every 10 or 20 or 50 years, you've gotta pull that thing out, disassemble, and clean/re-grease it.  Among other things, it provides an opportunity to check the bearings which the shaft goes through.

You beat me to it!

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