In rec.aviation.owning Bob Chilcoat wrote:
snip
: Another possible failure mode is for the screw to strip so badly that some
: or all antiservo function of the tab is lost. This could result in extreme
: difficulty in controlling pitch. Anyone have thoughts on how bad this might
: be? I have trouble imagining the screw stripping rapidly to the point that
: the screw could slide freely up and down inside the drum, but it might be
: possible. How can we find out how bad this would be? Is the antiservo
: function essential for flight control, or is it just to improve the "feel"
: of the controls?

I would think the worst-case scenario would be to have the anti-servo tab
floating, which would happen if the thing stripped completely. I also
think that this is the most likely scenario! When the remaining acme threads
on the jackscrew/trim drum get too thin to support the forces involved,
the whole mess will probably stip out all together. If you're lucky, it will
jam at some indeterminate point - if not, it'll float.

By the way, this is usually caused by grit or sand getting into the grease,
and wearing out the load-bearing surfaces. I'll probably take mine apart
and clean the grease out at annual.

As far as continuing to fly it, for the straight-wing version, Piper says
the maximum free play at the tab trailing edge is 0.150 inches (page 2A12
in service manual). If your free play is smaller than this, it's probably
OK to fly it someplace to get it fixed. I wouldn't wait 9 months, though,
I would fix it right away. I don't like to worry about the flight controls.

--
Aaron Coolidge (N9376J)