A/p wandering

Theboys

Theboys

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Theboys
I wondered if anyone has any experience with a kfc150 autopilot wandering in nav mode. It's like it's searching for course back and forth. Works fine on heading mode. Was thinking maybe problem with Hsi?
 
start with all the connections. Find every connection related to the autopilot that you can, disconnect, clean with contact cleaner, then a shot of corrosion-X and plug back in. Don't forget the one on the DG and the ones for each servo.

Look for anything related to the autopilot that is a ground to chassis and make sure it is clean and tight.

you say nav mode, do you mean VOR, gps, ILS, all of the above ? Try to narrow it down to fewer modes. Is it rock solid in heading mode ? If you need to get a technician to help these are the things that will steer him/her in the right direction

good luck, it can be frustrating but check everything you can yourself before paying $$$ for it.
 
It never hurts to call Autopilots Central in Tulsa - they're helpful folks even over the phone.
 
I have had 'wandering' autopilots over the years.
In every single case it was an injection of AMU's that cured it.
 
Depends on the specifics of the plane, but the nav signal itself can have variations/scalloping at the aircraft - the dampening factor in the AP can cause some variation in course. But yes, easy enough to get checked out.
 
Any time I have had a "wondering" AP is was due to settings being off. I think it is called "Gain" or "Sensativity". Try breaking out the manual or calling the company. They will usually have a fix in the settings mode that is easy to do.

Good luck! Let us know what works!
 
It stays pretty steady in heading mode but wanders in gps. Everything else including approach mode and glide slope work fine. Especially notice over 200 kts.
 
Set the GPS to the more sensitive setting. Mine has 5, 1 and .3miles per tick. Helps to set it on .3.
 
Add roll steering and you'll be much happier. I don't see anything in the panel pics to indicate it would have it.

Suspect that will cost a hand full of AMU(s) but worth doing while you're getting that new audio panel :)

Without roll steering, honestly, you're better off to just leave it in HDG mode and command the headings you need to maintain your GPS course. I never bother with trying to have an autopilot fly a GPS nav course without it.
 
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To get to the setting above, Use the big knob to the right until you get to AUX. Then the little knob to move to the 3rd page. Then select CDI / Alarms. The setting will look like this:

bFUMoQ4.png


YMMV, but the above should get you close to finding it.
 
I had a plane with a Blue Mountain EFIS in it. It would start "wagging" back and forth 20 miles from the destination. I used it to wake me up. :D


;)
 
jesse said:
Without roll steering, honestly, you're better off to just leave it in HDG mode and command the headings you need to maintain your GPS course. I never bother with trying to have an autopilot fly a GPS nav course without it.
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I agree that roll steering is better, but I've probably flown 1,000 hours with Century IIIs in different planes that track a GPS/NAV course just fine with no GPSS steering.

Jeff's first step of finding and cleaning all connections is likely a good idea. Also check the pins to see if any of the female sides are too big. Vibration can cause that over time. I had that happen on my AI which was causing a wandering back and forth in any mode, the AP just didn't get a good roll signal.

If this plane is new to you, don't be surprised if the AP takes some work to make right. I like the KFC 150, though, so I would try to make it work vs considering a new AP. Even my Century III I've settled on keeping. At some point I need to figure out the altitude hold issues I'm having.
 
Ted DuPuis said:
I agree that roll steering is better, but I've probably flown 1,000 hours with Century IIIs in different planes that track a GPS/NAV course just fine with no GPSS steering.
Click to expand...

Sure I'm not saying it can't be done, I'm saying that he's coming from a plane that was GPSS equipped so this isn't going to do what he was used to. The real utility without roll steering is pretty limited. Given how simple it is to just set a heading it's not a bad option.

If you're flying an RNAV approach you pretty much have to use it in heading mode at least half the time without GPSS, unless of course you want to blow through courses and have limited success in recapturing them.
 
Depends on preference, and absolutely correct that if you're used to GPSS, non GPSS won't feel the same in all phases of flight. But in cruise, I prefer letting the AP at least keep track of the nav. That way when I get distracted playing on my iPad at least I'm on course. :D
 
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