Cherokee Electric Pitch Trim

[Jonathan Goodish]

I have a 1977 Archer II with factory-installed electric pitch trim. The
trim servo motor works in both directions, but it doesn't work well for
moving the cables. When the ambient temperature is warm, the electric
trim works acceptably but occasionally seems to "slip," and when it's
cold, I can forget about it. The manual trim wheel seems to have smooth
movement regardless of temperature, though it is a bit stiff in
extremely cold temperatures. When I run the electric trim, even in warm
temperatures, I can literally place my finger on the trim wheel and get
it to slip.

I do have the Piper maintenance manuals for the airplane, but it appears
that the maintenance manual for the electric trim system is not included
for the Archer II. I assume that either the servo clutch is bad or the
jack screw needs to be disassembled, cleaned, and reassembled due to too
much resistance (though the manual trim wheel is not hard to move).

Does anyone have a suggestion, or know where I can locate the
maintenance manual?



Thanks,
JKG

[Michelle P]

JKG,
The clutch needs work. Have the servo/clutch unit removed and sent out.
Michelle

Jonathan Goodish wrote:

>I have a 1977 Archer II with factory-installed electric pitch trim. The
>trim servo motor works in both directions, but it doesn't work well for
>moving the cables. When the ambient temperature is warm, the electric
>trim works acceptably but occasionally seems to "slip," and when it's
>cold, I can forget about it. The manual trim wheel seems to have smooth
>movement regardless of temperature, though it is a bit stiff in
>extremely cold temperatures. When I run the electric trim, even in warm
>temperatures, I can literally place my finger on the trim wheel and get
>it to slip.
>
>I do have the Piper maintenance manuals for the airplane, but it appears
>that the maintenance manual for the electric trim system is not included
>for the Archer II. I assume that either the servo clutch is bad or the
>jack screw needs to be disassembled, cleaned, and reassembled due to too
>much resistance (though the manual trim wheel is not hard to move).
>
>Does anyone have a suggestion, or know where I can locate the
>maintenance manual?
>
>
>
>Thanks,
>JKG
>
>

--

Michelle P ATP-ASEL, CP-AMEL, and AMT-A&P

"Elisabeth" a Maule M-7-235B (no two are alike)

Volunteer Pilot, Angel Flight Mid-Atlantic

Volunteer Builder, Habitat for Humanity

[Roy Page]

I bought a 77 Archer in July and had exactly the same problem.
Mine would only power trim in one direction and the trim wheel was stiff to
turn by hand..
Most likely it just needs a fine adjustment of the castle nut on top of the
friction drive clutch.
I worked the trim switch on the yoke while my A&P did small adjustments, one
flat of the nut at a time, until it was working great in both directions and
silky smooth when trimmed by hand. Put the cotter pin back in and job was
done in about 30 minutes.
Later I did clean and grease the jack screw at the tail because it was
pretty dry.
--
Roy
N5804F - PA28-181

"Jonathan Goodish" > wrote in message
...
>I have a 1977 Archer II with factory-installed electric pitch trim. The
> trim servo motor works in both directions, but it doesn't work well for
> moving the cables. When the ambient temperature is warm, the electric
> trim works acceptably but occasionally seems to "slip," and when it's
> cold, I can forget about it. The manual trim wheel seems to have smooth
> movement regardless of temperature, though it is a bit stiff in
> extremely cold temperatures. When I run the electric trim, even in warm
> temperatures, I can literally place my finger on the trim wheel and get
> it to slip.
>
> I do have the Piper maintenance manuals for the airplane, but it appears
> that the maintenance manual for the electric trim system is not included
> for the Archer II. I assume that either the servo clutch is bad or the
> jack screw needs to be disassembled, cleaned, and reassembled due to too
> much resistance (though the manual trim wheel is not hard to move).
>
> Does anyone have a suggestion, or know where I can locate the
> maintenance manual?
>
>
>
> Thanks,
> JKG

[[email protected]]

On Thu, 18 Nov 2004 01:08:53 GMT, Jonathan Goodish
> wrote:

>I do have the Piper maintenance manuals for the airplane, but it appears
>that the maintenance manual for the electric trim system is not included
>for the Archer II. I assume that either the servo clutch is bad or the
>jack screw needs to be disassembled, cleaned, and reassembled due to too
>much resistance (though the manual trim wheel is not hard to move).
>
>Does anyone have a suggestion, or know where I can locate the
>maintenance manual?

Assuming that the trim servo in question is not part of an installed
autopilot with pitch/trim authority, it is probably a PET-1 servo
(Piper Electric Trim).

Have you verified that the clutch is slipping, as opposed to the cable
slipping on the capstan? Both are typical problems.

The servo is simple and easy to repair, finding parts and a manual is
a lot more difficult than "fixing" it. This data is not in the
maintenance manual/IPC.

I know of several sources for this information, but unfortunately they
rely on repairing these units as a source of income.

TC

[Jonathan Goodish]

In article >,
wrote:
> Assuming that the trim servo in question is not part of an installed
> autopilot with pitch/trim authority, it is probably a PET-1 servo
> (Piper Electric Trim).

You are correct, it is the PET-1.



> Have you verified that the clutch is slipping, as opposed to the cable
> slipping on the capstan? Both are typical problems.

I have not. It is possible that the cable is slipping on the capstan.
Right now, the airplane is in the hangar of an on-field maintenance shop
because I'm having an avionics guy look at my strobe noise problem. I
thought it would be a good opportunity to have the local A&P address the
trim problem, which he's willing to do, but he has no experience with
this type of problem. The mechanic has located a source for the service
manual for the PET-1. I just hope that if he gets it, he will be able
to diagnose and repair appropriately.



JKG