Auto Pilot Failure - KFC 200 - Suggestions?

[Seth]

Hi MooneySpace-

I have had an autopilot failure in my 1983 Mooney M20J Missile 300.  It is the factory King KFC 200 autopilot.  I had it adjusted in 2011 when I purchased it has performed nearly flawlessly ever since - until yesterday.

I flew from GAI (Maryland just outside Washington, DC) to Peoria, IL - about a 3.5 hour flight.

When in the climb once clear of the SFRA and after picking up my IFR clearance, I set the autopilot and the plane immediately made a hard left turn and dropped the nose.  I disengaged the autopilot.  I figured I may have hit the backcourse button.  I hit Flight Director, then NAV, indicating I was coupled, I engaged the autopilot, and again, a few seconds later, hard left bank with a dropping nose.

I disconnected again.  I have hand flown acrross the entire United States and in all sorts of weather in my former 1967 M20F so I had no qualms hand flying, I just was not at the top of my game.  By two hours into the flight, my scan and skills were back where they should be.  I later made a flight into Chicago's airspace and landed at KPWK (Chicago Executive) to stay with my brother for the night.  I have meetings in Mequon, Wisconsin today, and then I take a few days off and visit Oshkosh.

Troubleshooting:  

It seems in any mode, when the flight director commands the autopilot to turn right, nothing happens.  When the autopilot commands the plane to turn left, it does, but since no right turn works, the plane continues to steepen it's left turn.  Even the straight and level just AP on function slowly starts drifting left and then banking a diving to the left as the left command is sent.  I'm not sure if the left command stays on or simply once selected, it can't go right, thus doesn't even level.  Even altitude hold mode only, since it uses the straight and level feature, slowly ends up processing to the left when a left correction is needed.  Not sure if it holds altitude in the left turn.

So:  Collective Wisdom:

1.  Is it a bad servo

2.  Is it a bad control board

3.  Where should I take it?  Local shop?  Autopilot's central in Texas?  The place in Tennessee that's similar?

4.  I'll be at Oshkosh - any suggestions?  Bendix / King booth?

Thanks!

-Seth

 

 

[aviatoreb]

Anyway you can hang on for like 6 months?  For the price it might cost you to repair that thing (same thing I have .... so I know...) you might be able to install one of the new generation of digital autopilots that are becoming available - GFC500?  Trio? TruTrek? Dynon?

[LANCECASPER]

Autopilots Central is in Tulsa Oklahoma, which Texans call North Texas.

Central Texas Avionics is Georgetown TX is also really good with King Autopilots.

[ArtVandelay]

I would try the simplest fix first, unplug the AP connectors and spray some electronic cleaner on it.

[Seth]

I just got a suggestion that Carpenter Avionics in Smyrna, TN is also really good and is much closer to me thatn AP Central in TX, but AP Central in TX without question is the place from what all the forum say.

Maybe I should hold off on the repair Erik!  A digital AP may make sense.  Then again, I'll still price out the repair.

-Seth

[Seth]

Just now, teejayevans said:

I would try the simplest fix first, unplug the AP connectors and spray some electronic cleaner on it.

I will try this.  When you say unplug the AP - where - the control unit in the panel? The unit in the avionics bay?  The servos?  All of them?

The AP test on the ground works fine - normal test at start up with no failure indicated.

-Seth

[aviatoreb]

9 minutes ago, Seth said:

Maybe I should hold off on the repair Erik!  A digital AP may make sense.  Then again, I'll still price out the repair.

The problem with autopilot repairs - is often you are not for sure which component is bad, so you send one part in, overhaul it, then when it returns and you still have the problem then you need to overhaul the next most likely part, and so on - all the while paying not just for overhauled parts but the labor for the r&r.  Ok - that is not so bad in that then you have a freshly overhauled system when you are done.  That's what I ended up doing with my then flaky KFC200 7.5 years ago when I got my airplane, and with the help of autopilot central (superb outfit) I ended up progressively overhauling just about the whole system.  But its worked well since, but yeah it was a significant cost to overhaul almost everything.

[PTK]

9 hours ago, Seth said:

Hi MooneySpace-

I have had an autopilot failure in my 1983 Mooney M20J Missile 300.  It is the factory King KFC 200 autopilot.  I had it adjusted in 2011 when I purchased it has performed nearly flawlessly ever since - until yesterday.

I flew from GAI (Maryland just outside Washington, DC) to Peoria, IL - about a 3.5 hour flight.

When in the climb once clear of the SFRA and after picking up my IFR clearance, I set the autopilot and the plane immediately made a hard left turn and dropped the nose.  I disengaged the autopilot.  I figured I may have hit the backcourse button.  I hit Flight Director, then NAV, indicating I was coupled, I engaged the autopilot, and again, a few seconds later, hard left bank with a dropping nose.

I disconnected again.  I have hand flown acrross the entire United States and in all sorts of weather in my former 1967 M20F so I had no qualms hand flying, I just was not at the top of my game.  By two hours into the flight, my scan and skills were back where they should be.  I later made a flight into Chicago's airspace and landed at KPWK (Chicago Executive) to stay with my brother for the night.  I have meetings in Mequon, Wisconsin today, and then I take a few days off and visit Oshkosh.

Troubleshooting:  

It seems in any mode, when the flight director commands the autopilot to turn right, nothing happens.  When the autopilot commands the plane to turn left, it does, but since no right turn works, the plane continues to steepen it's left turn.  Even the straight and level just AP on function slowly starts drifting left and then banking a diving to the left as the left command is sent.  I'm not sure if the left command stays on or simply once selected, it can't go right, thus doesn't even level.  Even altitude hold mode only, since it uses the straight and level feature, slowly ends up processing to the left when a left correction is needed.  Not sure if it holds altitude in the left turn.

So:  Collective Wisdom:

1.  Is it a bad servo

2.  Is it a bad control board

3.  Where should I take it?  Local shop?  Autopilot's central in Texas?  The place in Tennessee that's similar?

4.  I'll be at Oshkosh - any suggestions?  Bendix / King booth?

Thanks!

-Seth

 

 

Seth, did you notice what the fd is doing when this happens? If the fd is commanding properly it may be a servo related issue.

Also don't underestimate a gyro issue. The KI256 may be acting up. An easy action would be to swap gyros and see if it solves the problem.

Before doing anything you may want to call Autopilot Central and speak with Alan or Steve, (918) 836-6418. They can steer you in the right direction and may even help you diagnose the issue.

The KFC200 is an analog system and should be easy to troubleshoot. 

[PMcClure]

My experience - sounds like a servo. But I suggest you call AP central and ask for help. They have been great to give free trouble shooting advice over the phone to me (PP) or my mechanic or avionics tech. Then they can recommend taking the mostly likely component that needs attention and send to them for inspection and repair if necessary. Paul 

[carqwik]

+1 on AP Central.  However, I might suggest carefully documenting all of the failure modes...and modes where the AP does work properly.  AP Centrally identified the problem in my KFC-150 based on a phone call....very impressive since two other shops couldn't get even close to diagnosing the problem (and after too many $$ spent chasing the issue which they couldn't resolve!!  12 years later and I'm still pissed that I didn't go to A/P Central first!).

. 

[aviatoreb]

One great thing about AP central is they are so experienced with these autopilots, KFC200 included, is they can often diagnose the problem over the phone based on what you describe to them is the problem.

[peevee]

4 minutes ago, aviatoreb said:

One great thing about AP central is they are so experienced with these autopilots, KFC200 included, is they can often diagnose the problem over the phone based on what you describe to them is the problem.

we had a not so great experience with them recently. You can send your AI and AP to bob bramble in FL and he'll troubleshoot it on his test bench. He doesn't charge for diagnostics.

[ArtVandelay]

I will try this.  When you say unplug the AP - where - the control unit in the panel? The unit in the avionics bay?  The servos?  All of them?
The AP test on the ground works fine - normal test at start up with no failure indicated.
-Seth

Attitude indicator connection, AP controller and servos .
When you do the ground test, did you try putting it in heading mode and check that it follows the bug left and right?
If it fails the heading test, then I would think its a servo problem, if it passes ground tests then I would think AI/controller. But I defer to real experts.

[CaptRJM]

Autopilots Central is the best place that I know of.  They rebuilt my controller a few years back and I have had no problems since.  But, it was around $4,500 since they replaced all the capacitors in the box.

You may have 2 problems,  nose drop is often a problem with the trim servo.  The hard turn could be a number of things.  I agree, call Autopilots Central and get their take on the problems.  If you end up having the 256 or the controller rebuilt or overhauled make sure you have a good avionics shop that can "marry" everything together.  This will insure optimum performance.

[carusoam]

Reviewing...

1) the box on the panel runs through the tests OK...

2) AP Central known for their work...

3) Bramble known for his BK gyro work...

4) BK servo for controlling altitude known for wearing... it works hard.

5) failure sounds like somebody grabbed the yoke and tried to make a turn...

Makes me want to look closer at the inputs from instruments... sounds like they may be misguiding or unguiding the AP.

Go to the BK site, see which BK instruments are connected to your BK AP...

Disconnect, clean, reconnect.

Checking in with Mr. Bramble could be a really good idea...

 

This is goofy PP thinking, dangerous to use for AP use in IMC...

Best regards,

-a-

[MooneyMike280]

This may or may not help.

Good luck with everything...

Mike

 

 

[Alfa407]

 

Hello good night, my kfc 200 does not engage the nav mode signal on the gps, and in flight sometimes it starts making ascents and descents, like a dolphin. Can someone tell me if it is the kc 295 computer or the pich serbo, thanks

[carusoam]

Good evening, Alfa...

Expect that the pitch Servo is the most likely wear item in the system...

There is probably a set of next steps to follow to test things related to wear... it might have a clutch in the Servo....

Often Jake  from Bevan Aviation gets mentioned for Servo maintenance...

@Jake@BevanAviation 
 

Maybe Jake can give some insight on the situation...

Best regards,

-a-

[GMBrown]

Seth:

Its been a while since your KFC 200 started acting up (5 years!), but I was wondering (and hoping) that things ended up well.  I didn't see a final resolution in the string above. Did you get the problem resolved?  I have a KFC 200 so I am interested in how/if things got resolved.  

Thanks

G

[Fly Boomer]

@Seth

[PT20J]

7 hours ago, GMBrown said:

Seth:

Its been a while since your KFC 200 started acting up (5 years!), but I was wondering (and hoping) that things ended up well.  I didn't see a final resolution in the string above. Did you get the problem resolved?  I have a KFC 200 so I am interested in how/if things got resolved.  

Thanks

G

A few places still work on those

Bevan

Mid-Continent

Executive Autopilots

Autopilots Central

[PeteMc]

8 hours ago, GMBrown said:

I have a KFC 200 so I am interested in how/if things got resolved. 

Where are you located?  In addition to the places @PT20J mentioned.  I believe LV Avionics at Allentown (KABE) works on them. 610-264-1430

I do know that he works on the Servos and often just cleaning and tweaking can make a BIG difference and extend their life.