Trim wheel stuck in a down position

[lithium366]

I had this happen several times during maintenance: I put the trim wheel all the way down and then it is stuck in this position not turning anywhere until someone goes and turn the rod in a battery access panel. Then it loudly clicks and start working again. Kinda scary if I am not careful and turn it all the way down in flight

[lithium366]

To clarify: I don’t have an electric trim, only manual

[ShuRugal]

Apply less force to the trim wheel when moving it. Most likely cause of this is that you are running the block which pulls the indicator cable into the end of its travel hard enough to jam the threads.

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[Guest]

I doubt you’d ever need to run the trim wheel fully nose down in flight, so it’s unlikely to jamb.  However jamming in full nose up is a possibility, there are several bulletins on this subject.

Clarence

[N201MKTurbo]

There is a service instruction about this. 
 

http://www.mooney201.de/files/sim20-88.pdf

[carusoam]

Mechanical things with screw shaped shafts have a tendency to jam at the ends…

Really a problem for electrically powered trim… where the electric motor can bump the end pretty hard without the operator knowing the end was getting closer, compared to hand driven systems…

See if you can determine the cause of the jam…. To make sure that it is only occurring because it reached the end….

If you have ever locked one nut on a bolt using a second nut…. Aka buddy nut… you can see how hard this can be to undo from the cockpit end…

Run away trim systems can be extra hazardous…  they can generate near a hundred pounds (?) of force on the yoke… which can be hard for some people to provide for a period of time long enough to be on the ground…

As far as trimming full downwards in flight… I have never been there… I may have experimented with the flight envelopes with my M20C…. But, full down trim and really high descent rates, and Vne are probably going to keep you from going that far down on the trim setting in flight… on purpose.

Check to be sure…

PP thoughts only, not a mechanic or CFI…

Best regards,

-a-

[amillet]

Haven’t done it in the Mooney but my wife has jammed the travel trailer electric jack a couple of times. The first time required disassembly, a vice and breaker bar on a socket to break it loose. 

[SheryLoewen]

Mooney has a kit for this problem It adds some idler bearings so the end travel doesn't jam.

[carusoam]

@lithium366 Ilya, see the note from Shery above…

Best regards,

-a-

[PT20J]

The SI is for Js and later. I’m not familiar with earlier model trim systems. I know that some were so loose that they had friction devices added to the trim wheel. With later models people usually complain the trim is too stiff. Has anyone installed the step nut stops on earlier models?

Skip

[ArtVandelay]

There is a service instruction about this. 
 
http://www.mooney201.de/files/sim20-88.pdf

The J version of the SI kit is something like 2 AMUs….too expensive for me, I just need to be careful, only has happened once.

[N201MKTurbo]

6 hours ago, ArtVandelay said:

The J version of the SI kit is something like 2 AMUs….too expensive for me, I just need to be careful, only has happened once.

If you put a thin washer at each end of the indicator, it will do the same thing for $0.50

[PT20J]

19 minutes ago, N201MKTurbo said:

If you put a thin washer at each end of the indicator, it will do the same thing for $0.50

The original stops formed jam nuts. The stepped stops prevent the nuts from tightening against each other and jamming. Where do the washers go, and how does this solve the jamming? 

[N201MKTurbo]

The problem is the stops on the indicator jack screw shaft get jammed against the aluminum end plates with the bearings. I had this problem with my old F. I took it apart and got some 0.010” shim washers from McMaster and put them on the shaft at each end. They are floating, but usually stick to the end plates. They give a better bearing surface than the aluminum on aluminum interface. After I put them in there, it never got stuck again.

[kortopates]

The J version of the SI kit is something like 2 AMUs….too expensive for me, I just need to be careful, only has happened once.

someone led you astray. i don’t recall exactly how much, as it was a few years ago, but the kit was only a few hundred for the hardware. it’s not that time consuming either during an annual.


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[ArtVandelay]

someone led you astray. i don’t recall exactly how much, as it was a few years ago, but the kit was only a few hundred for the hardware. it’s not that time consuming either during an annual.


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The J kit includes a new trim screw, IIRC that’s +1AMU alone. I called Laser.

[ArtVandelay]

The problem is the stops on the indicator jack screw shaft get jammed against the aluminum end plates with the bearings. I had this problem with my old F. I took it apart and got some 0.010” shim washers from McMaster and put them on the shaft at each end. They are floating, but usually stick to the end plates. They give a better bearing surface than the aluminum on aluminum interface. After I put them in there, it never got stuck again.

You wouldn’t happen to have any pictures?