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Removing Piper Electric Trim (PET-1) motor

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Aug 21, 2010
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The PET-1 in my '73 -180 was inop when I bought the plane. I know fixing this gizmo can eat up a bunch of $$ in a hurry and it's not required if the manual trim wheel works fine (which mine does, of course). However, it bugs me to have something in the plane not working properly, so I'm going to try to take a look at it when the plane goes in for annual next week.

I know the yoke switch is bad (it has physically fallen apart). I have a replacement switch in hand and have inspected the wiring under the panel. I am confident I can replace that switch (under my A&P's supervision) with no problem. It's possible that once I replace the switch, the motor will start working like it's supposed to, and the heavenly host will break out in a big "hallelujah" and the skies won't be cloudy all day.

But what I'm expecting is that I'll replace the switch, and there'll still be no response from the trim motor when I turn everything on and try to actuate it...'cause ain't nuthin' ever easy.

So my next step will be to do a continuity check and make sure power's getting back to the motor. If it is, then the next step will probably be to pull the motor from behind the rear bulkhead and put in on a bench and see if there's anything my A&P can do to it. i've read the bajillion posts from POS, and I know there are places (Muncie Aviation, et. al.) I could mail it off to for possible overhaul, but before I do that I might want to try to pop it open and look for user serviceable parts inside.

I've got the Piper Pitch Trim service manual (p/n 753-771). It is not as explicit as I'd like it to be on how to remove the motor. Mine is mounted to the floor of the fuselage (not the roof like older planes), and it's not immediately clear to me sticking my head and shoulders through the bulkhead opening exactly which bolts to loosen to get the unit out of the plane. The service manual simply says, "Remove four mounting bolts securing the servo assembly to the mounting brackets," but part of the assembly seems to back up underneath the baggage compartment floor, and I'm not sure how I'd get to any bolts back there...if I did manage to get them out, I'm not sure how I'd get those fasteners back in!

Is there a trick to the removal? Am I missing the obvious and it's so straightforward that I'm just an abject idiot for not seeing it? (Since no one else asked this question in the bajillion POS postings, I'm guessing "idiot" is the answer.)

Any advice from someone who's done this before?

Thanks,
Jim
 

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