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Old April 21st 08, 05:50 PM posted to rec.aviation.owning
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Default Piper single axis autocontrol question.

I don't know the pipers well enough to comment specifically,
but this surely shouldn't be happening. it's a safety of flight
issue.

The cable should be constrained so it can't slip on the capstain.
Sometimes this is done with a bead staked on the cable in the
middle of the capstain... it drops down into a small hole in the
capstain. There might be other mechanisms to do this, but there
will be some way to do this.

If the travel isn't well centered, something may collide near the
end in one direction or the other. There usually isn't a lot of
excess travel available; that is they only use enough wraps to
get the job done in the first place.

You may want to loosen the bridle cable clamps and reposition
them slightly so that travel to each end is the same.

The cables should have some tension in them; if they are loose,
the autopilot may oscillate.

bh



On Apr 19, 5:50*pm, "Mike Noel" wrote:
My '74 archer developed an intermittent problem where the aileron would have
a 'soft stop' at one end of the control throw. *I thought a mechanic might
have left a rag or some such under the floor that moved around and sometimes
prevented full control deflection, so I removed the floorboard under the
back seats. *I found instead that the aileron servo pulley had several wraps
of cable and what appears to be a pin stake to keep the cable against the
pulley, presumably to prevent the cable from sliding on the pulley. *At one
end of throw the pin stops the cable from unwrapping from the pulley and the
cable bends down, giving the feel of a soft stop.

Anyone familiar with the mechanics of this arrangement? *My best guess is
that the cable is actually sliding around the pulley slightly when I help
the autopilot in rough air and sometimes the pin is in a position to allow a
natural hard stop and at other times it stops the aileron short of full
throw.

--
Best Regards,
Mike

http://photoshow.comcast.net/mikenoel