D180 autopilot wallowing

[dothetime]

I have a 601XLB, d180 with a SV42 roll servo only.
When heading or tracking autopilot wallows, turning left and right trying to follow a heading or track.
Tried numerous settings, works best on max sensitivity (25)
Max torque 100%
shear screw ok, aileron cables as tight as possible, reenforcement plate under servo for stiffness. When on the ground, with autopilot on, in track or heading there is some play in the ailerons.
Don’t know what else to try.
open to suggestions.
Could it be the D180?
Dave
601XP

 

[DBRV10]

Have you pulled the arm or capstan disc off and physically inspected the shear screw. Just because you can see the head, and it seems to work on the ground does not mean it is not broken.

When they break there is often enough broken screw to still provide enough friction to make the ailerons move, but not enough to work under flight loads as the servo keeps rotating.

I have replaced a few on peoples planes with exactly the same claim you are making. So go check it fully. You might be surprised.

 

[dothetime]

Have you pulled the arm or capstan disc off and physically inspected the shear screw. Just because you can see the head, and it seems to work on the ground does not mean it is not broken.

When they break there is often enough broken screw to still provide enough friction to make the ailerons move, but not enough to work under flight loads as the servo keeps rotating.

I have replaced a few on peoples planes with exactly the same claim you are making. So go check it fully. You might be surprised.

Thanks for the response
I’ll check it again.