KAP140 Autopilot problems

Matt Todd

Filing Flight Plan
May 6, 2021
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Matt T
I have a 2003 Cessna T182T (non-G1000) that has a KAP140 AP.

The ongoing problem I have is that after a period (time varies) in flight using the AP the aircraft will start to drift left of course regardless of whether it is in HDG or NAV mode. It won't respond to the HDG bug. I have to disengage and then re-engage the AP to get it to respond.

There are never any errors logged, no find anything when we test it.

I had the HSI checked, then we swapped it out and eventually replaced it with a Garmin GI275.
We swapped out the TC, still a problem.

On that back of that, we figured the problem must be in the AP computer, so we got an exchange unit. Still a problem!!

So 12 months and many thousands of dollars later I still don't have an AP I can rely on.

Has anyone else had a similar problem and/or any idea how to fix it?


Have you talked to Autopilots Central in Tulsa?
Thanks, I am based in New Zealand and have been working with one of the local but reputable avionics shops here, but we just seem to have hit a wall in terms of diagnosing the fault.
Have the servos been checked?
We replaced the pitch servo a few months ago, but we haven't looked at the roll servo. What would we test for to try and diagnose a fault.
Hi Matt,

Interested to know if roll servo maintenance was required and if it resolved the problem. I'm seeing the exact same problem recently in my 2003 182T.


Hi Jason,

They did check the roll-servo and in particular the clutch, but couldn't fin anything wrong with it.
Most recently the GI275 faulted (heading) and so it went back to the shop. They fixed the GI275 and reset all the nulls, My friend Rayden flew it home (just over 1 hour) and said there were no AP problems. I need to get a few flights logged before I would be comfortable to say we have resolved the fault. I am trying to do final consolidation for my instrument flight test which has made these problems doubly annoying.
So far we have swapped out the AI and TC, the refitted originals (as the fault was still present). Replaced the pitch servo (seperate fault). Swapped out the HSI then replaced it with the GI275, checked the roll servo. Redone the nulls on almost every occasion.

Hopefully it is sorted, but if I knew then what I know now I would have thought very seriously about replacing the KAP140 with Garmin GFC500.


Hi Matt,

Curious to see if the issue was resolved and what the fix was.. Having a similar issue with a 182T.