Thread: Autopilot question

Okay, here's a new one for you all... When flying back to Tulsa I had perfectly SMOOTH air most of the way. As you know, my AP isn't working, but I still had wing leveller mode and altitude hold mode. When I got up to altitude and levelled off, I noticed that the altitude would fluctuate about +- 50 ft. Also, when I would lightly touch the stick, I could feel the elevator servo moving back and forth ever so slightly to keep altitude.

I used a King/Honewwell KAP-140 AP in the Cessna and never noticed it. The altitude seemed to be dead on and only severe turbulence would let it fluctuate. I also realize the King is IFR and approach certified with a cost of 20 times more, but maybe I'm just expecting too much from the FD AP.

Is this normal? It just seems the servo has to do ALOT of work if it's constantly moving back and forth like that. I did have it in trim so there were no "up or down" lines moving on the AP.

Also, the wing leveler mode had to be flown in a 10-15 degree right mode just to keep going straight. Could this be caused by my weight in the left seat and the right seat being empty? Maybe I wasn't on level ground when I started up? I don't even know if you can access the wing leveler mode when the GPS/HDG modes are working, but was just curious...

Thanks

John

if your ap is flying in a bank then trim your rudder, isn't your slip / skid ball off when the ap fly's in a bank?

my ap has gain settings that i can use to adjust if it overshoots its target and keeps oscillating

No the ball was right down the middle/centered. I made sure of that with the trims. When the plane gets back, I'm going to definitely read the AP manual VERY CLOSELY so I can really fine tune it. Thanks,

John

ball centered, holding course in a bank. i'm pretty sure this is a demonstration of a slip / skid ball that is off. trim your rudder for level flight while holding course and you can see where you ball needs to be. is it adjustable?

the ap adjustments might be part of the installation procedure ?