Autopilot Debate

[N3322G]

Charles,

The Piper Inspection Form calls for
Fuselage Group Item #25 to inspect security of A/P bridle cable clamps
Operational Inspection #20 Check Operation of Pitch Trim if installed

so unless you asked Heritage to check tension, I wouldn't expect it to be done.

[Charles Schefer]

Thanks Pat. I'm sure you're right but I'll check anyway. A quick phone call is worth making before spending money...

- Charles

[N3322G]

Had a great Comanche maintenance session with the CTPT group at Clifton last week with 22 folks and 4 speakers. Cliff Wilewski of Heritage spoke on several topics, one was working with your shop. He commented that different shops have different styles, his is that he prefers email questions unless the plane is in the shop and there is an issue. That way he has a chance to look up any pertinent info or talk with his team before answering a question. Tim Talley, Clifton owner had the same remark and added that it means he doesn't have to take his hands off an airplane to answer the question. Sure made sense to me. thought I'd pass along one of the class tidbits.

Another tidbit was the inspection form i referenced. It is in the maintenance manual but they handed out a nice clean copy with more notes than I had previously seen. Always an education to browse it.

[Charles Schefer]

Thanks Pat it was actually Cliff Wilewski and his team at Heritage that did my Annual (among other things)... While the plane was there they more or less rebuilt the landing gear with a new Matt Kurke Dura Gear Motor and Transmission, new Webco Teflon Push-Pull conduits, new Matt Kurke gear wiring kits and micro switches, 1K Gear AD, 500hr Gear AD and other stuff. New STC Aux Fuel Pumps as well... Anyway I sent Cliff an email earlier today saying I am guessing they didn't record actual cable tensions during the annual but if by chance they did could he tell me what they were. He always responds in due course...

[N3322G]

Charles - too funny!
It is off thread but i have to tell you I was very impressed by Cliff, his enormous Comanche knowledge and his humility. In turn, Cliff was quite excited to actually meet Tim Talley of Clifton and vice versa. Like Comanche owners get excited to meet other Comanche owners - so do the mechanics maintaining the same type aircraft. I heard them comparing tools after the session - I know they will be talking again.

[Charles Schefer]

Pat - Also to funny but...

Cliff replied to my email this weekend and started off by saying that he had obtained new throttle rollers (for the micro switches - I'd been emailing with him on that too - think I'll still replace mine even though I think we've solved that for how) and as part of that Cliff said he'd been chatting with you on that topic. I told him you and I had been communicating as well on that and other topics... Funny

PS - back on thread - you are right... Cliff said they check the cables and only check tension if they suspect a problem. In the case of my plane they did not because cables were good.

[N8632Y]

Charles,
I originally had your autopilot. Loved it, but i did build my avionics up piece meal, without a big picture in mind. Of course things are changing so quick, so who could?
But, the little trim window, top left that you say when you are in altitude hold, and the plane is level, but the trim indicator is pitched down slightly? I believe that is correct, IIRC, the twinky in flight gets on step and actually does a slight nose down.
I also think that is why a speed mod, or kind of mod, is the 3 degree aileron deflection, to take it out of drag.
steve

[Charles Schefer]

Thanks Steve that is interesting - I hadn't heard of the aileron deflection adjustment before. I assume the deflection would be 3-deg up on each side? If deflecting down I would think that would remove safety by promoting the wing to stall first on the outer side of the wing not at the root.

On the autopilot - I believe the trim window (upper left of the AP unit) has nothing to do with the attitude of the aircraft. It has to do with the barometric pressure as sensed by the unit in comparison to the barometric pressure desired based on the altitude selector. As I understand it, all the trim window tells you is whether the autopilot believes it needs to initiate a climb or a descent from the current altitude (baro) to reach the pre-selected altitude (baro) on the altitude selector. This is based on barometric pressure not the pitch-up or down attitude of the aircraft in flight. So on mine, on the occasions where I can get it to hold altitude the trim is still saying that it wants to command a descent to reach the altitude I am already at when it should be level.

Anyway that's what I think based on my read of the book but I could be wrong - it wouldn't be the first time (just ask my wife )

- Charles