Balky aileron trim

[Paul Eastham]

Hi,
I have noticed that my aileron trim servo can move quite a bit (1/4"?) before the control horn starts moving. What seems to be happening is that the plate that the horn is mounted on (the one the sits flush against the seat pans) is bending inward and outward before the horn starts moving.

(The control horn is not yet hooked up to anything.)

It wouldn't be too hard to reinforce the plate, but thought I'd check to see if others have seen this before I go waste an afternoon on it...

Thanks - Paul

[Scott Will]

Paul,

Mine appears to do this too... I've asked about it in the past and it seems 'normal'. I've thought about looking into it - maybe after I'm flying. The angle at which the arm is located doesnt help either.

- Scott

[Davepar]

I've got the same thing on mine. I'm hoping a) with the seat cover in place the plate will deflect outward (upward) less and b) the plastic block will loosen up over time. I've noticed that those plastic blocks are slightly compressible. I might try loosening the screws holding it in place.

[dan]

As lame as I once thought the aileron trim design was (talking RV-7/-9[A] here), and as much "flex" the thing can have, I gotta say it works absolutely FINE. Carry on...

[lucky333]

I'm just putting my trim in now so this is of interest. It sounds like there is a lot of friction and/or some misalignment in your trims.

For the record, my actuator horn spins easily in the plastic block but its not wobbly. I noticed that the hole in the servo arm was undersize so I reamed it to fit the clevis pin. To locate the servo after bolting in the actuator horn assy, I first ran it fully in and out to find the center of its travel and marked it on the moving shaft. Then I hooked it up to the actuator horn assy (F-6124 et al) with the clevis pins, washers and other junk. I located the servo loosly on the seat rib web fore and aft and clamped it lightly in a position that located the actuator horn in the middle of travel when the servo arm was at its midpoint. Finally, I ran the servo in and out using a power supply and let find its way and align itself, helping it move as necessary for minimum mechanical binding. I tightened the clamp and tested the alignment and did not find any binding or bending. The clevis arms and pins are loose over the whole travel of the servo.

Its still clamped as I write but I figure it will run true when I drill it in. I hate to disagree with Dan (1K hours on his and I'm still bending tubing) but I think if you have that much bending, its an indication of mechanical unhappiness and you should investigate and clean it up as able.

Hope this helps.
John