Ramifications of Cherokee Trim Jackcrew Failure

If the stabilator on the Aztec is the same as that on the Cherokee, the
antiservo tab isn't the sole thing driving the stabilator, although it looks
like it. If you take the top half of the tail cone off, you can see a large
tubular rod extending forward into the tail from the main pivot for the
stabilator. I'm told that this has a counterweight on the end inside the
tail, and that the main control (don't know if it's a rod or cables) from
the yokes attach to this. The only cables going to the trim jackscrew are
the ones from the trim control between the seats. If the trim jackscrew
stripped out, you would not lose the ability to move the stabilator with the
yoke, but you might lose all antiservo action of the tab, depending on the
failure mode. This may or may not be a complete disaster. The reason there
is antiservo action is so that the forces on the stabilator don't result in
positive feedback as you move the stabilator away from the neutral position.
Since the center of pressure moves with AOA, without the antiservo action
the normal aerodynamic action would be to push the stabilator farther from
neutral the farther you move it, the opposite of what you want. At least
that's the way I understand it. Can you fly with it like that? Don't know.
Don't want to find out.

We're rapidly reaching the conclusion that we should get it sooner rather
than later.

--
Bob (Chief Pilot, White Knuckle Airways)

I don't have to like Bush and Cheney (Or Kerry, for that matter) to love
America

"pacplyer" wrote in message
om...
Bob, I'm kinda worried about this. On my snub-nose Aztec the
stabilator has a similar "antiservo" surface that "drives" the entire
stabilator. By pulling on the yoke you are first moving that tab
which in result "flys" the entire tail to a new pitch command
position. Loss of control of that tab suface (i.e. trim jackscrew
unexpectedly strips) at least on my bird, will not just loose trim,
but could, if it shears past the limit, loose all longitudinal pitch
control.