KFC-200 won't command flight controls

[anthonydesmet]

Hello Mooney folks,

Had a great flight this morning for business with auto pilot working fine.  Then came home tonight and tried to engage autopilot but I had no command to the flight controls and no altitude hold.  The magnetic autopilot switch would engage and I could slew the heading bug and watch the flight director cue move accordingly but the flight controls and yoke acted as if the autopilot were not engaged.  Pressing test I would get the 5 beeps for the trim and all associated lights on the display.  Ground test did not work also.  I have a call into autopilot central in Tulsa for tomorrow.  Thoughts?

[carusoam]

I My AP gets confused when my power trim is turned off... but there is no indication the trim has been off...

A nice way of saying...  check to see if the power trim is working.  Without it, the AP just looks at you funny.

Best regards,

-a-

[anthonydesmet]

Thanks Carusoam.  But yes, the electric trim was engaged and works fine.  When I disengaged the electric trim I would get the flashing red trim light and warning tone.  I was thinking that so I disengaged and reangaged to see if it was the reason you are saying. 

[Rmag]

7 hours ago, carusoam said:

I My AP gets confused when my power trim is turned off... but there is no indication the trim has been off...

A nice way of saying...  check to see if the power trim is working.  Without it, the AP just looks at you funny.

Best regards,

-a-

Done that before.  Quick stop at another airport where I shut down, quickly went through the startup procedure and took off.  Didn't try the autopilot but the electric trim wasn't working.  Had to spin the wheel to trim after gear and flaps were up.  I'm thinking, "great now my electric trim broke".  Then I looked at the little "Trim" switch...

[Oldguy]

Strange thing I had happen was the red disconnect button on my yoke came partially unscrewed. All test ran okay, but would not engage. I do not have a FD, so I am not sure if the symptoms would be the same. Might give the yoke control switch a good look to see if something is stuck/broken (CWS fully depressed?). It sounds as if the system is functionally capable, but the connect signal is not being received. Hopefully it is a quick and inexpensive fix.

Oh, wait, it is an autopilot problem. 

[anthonydesmet]

Quick follow up - I talked to the folks at mid continent and autopilot central and after some over the phone troubleshooting in the plane I need to send the autopilot computer that sits in the avionics bay to them to bench test.  They think it's either a distribution line on the circuit board that sends the signal to the pitch and roll trim servos.  Apparently there is just one line that sends this signal. If the bench test is good they think I may have a short in a wire harness.  In any case they seemed to have dealt with this before.  I am also sending the control module but they think it is functioning properly since the on switch magnetically holds and the module is sending all the right info to the displays. More to follow.

 

yoke CWS and TRIM switch are both good.

[carusoam]

Take a picture of the boxes on the shelf, if able...

There are things there that take years to know what they actually do.

one of the weird failures of an AP systems was a large capacitor in the panel mounted box...  Somebody shared the picture and details...

Best regards,

-a-

[flyboy0681]

17 minutes ago, anthonydesmet said:

Quick follow up - I talked to the folks at mid continent and autopilot central and after some over the phone troubleshooting in the plane I need to send the autopilot computer that sits in the avionics bay to them to bench test.  They think it's either a distribution line on the circuit board that sends the signal to the pitch and roll trim servos.  Apparently there is just one line that sends this signal. If the bench test is good they think I may have a short in a wire harness.  In any case they seemed to have dealt with this before.  I am also sending the control module but they think it is functioning properly since the on switch magnetically holds and the module is sending all the right info to the displays. More to follow.

 

yoke CWS and TRIM switch are both good.

So which one of the two are you going to send it to? I've used them both to service my KAP 150 and I can't recommend one over the other because they were both great to deal with.

[anthonydesmet]

Carusoam, will do when i get back out there tomorrow.  Google KC-295 autopilot computer and you will see it.  Basically a blue box with two square wire harness connectors and a single line in from your static system for the altitude hold.  

Flyboy, I am sending it to autopilot central. 

 

Personaly i I think I have a shortered wire and tomorrow I am going to pull some panels to take a look and see if anything is obvious before I pull the boxes.  That's why I didn't pull them today and I didn't have time to look behind panels. Reason being is that on takeoff at gear up I remember smelling something like a little burning but there was also some controlled burning a few miles from the airport. So I discounted it and also thinking that would have popped the cb. But looking back the smell seemed a little more intense than outside ground burning.  Plus it did cause me to glance at the cb panel but the smell was over before it started.  I could be talking myself into things but it doesn't cost anything to look.  Plus a nice Friday morning at the airport.....who wouldn't that.....

[milotron]

In the logs of my M20k ( 262 also ), the KFC 200 was doing something similar and turned out to be the conductors to the CWS ( control wheel steering ) pushbutton in the yoke. These wires would short/ground and prevent the AP from doing anything regardless of settings or commands.  They evidently couldn't find the issue so just disconnect the wires from the computer and the switch is now placarded as INOP. It looks like they replaced a number of parts and spent ALOT on labour to get to that conclusion...

It is on my list to re-wire it and bring it back to life.

iain

[thinwing]

Waiting for final report

[anthonydesmet]

Uhhg.

just heard back from autopilot central.  Had a few issues.  Here is the bench test results: 

PRELIMINARY INSPECTION: Bench tested; unit needs securing hardware; has old style filter capacitors; connectors have sticky

substance on them; pitch rate caps are faulty and need replaced; no other problems seen at this time.   Looking a little over 3AMU's to fix

[anthonydesmet]

On 8/21/2017 at 7:25 PM, anthonydesmet said:

Uhhg.

just heard back from autopilot central.  Had a few issues.  Here is the bench test results: 

PRELIMINARY INSPECTION: Bench tested; unit needs securing hardware; has old style filter capacitors; connectors have sticky

substance on them; pitch rate caps are faulty and need replaced; no other problems seen at this time.   Looking a little over 3AMU's to fix

Quick follow up - I finally got a chance to talk to the folks at autopilot central yesterday.  The above information addresses preventative maintenance that should be performed on my flight computer and module.  However after talking with Allen and Stan, it does not address my primary issue of the autopilot engaging the clutch to drive the servos.  After the discussion we are moving onto a faulty wire (oh joy).  The plus side of this is that I am going into annual tomorrow so the airplane will be torn down to parade rest and I will have access to behind the panels a lot easier.  They are also sending back my computer and module this week for the troubleshooting.  Personally I still feel there is something up with my CWS switch since the airplane acts as if that button is depressed when the autopilot is engaged.  I.e, all autopilot engaged indications are present accept the servo's driving the controls which is exactly what happens when the pilot depresses the CWS switch.  This also sounds like what militron had above plus would account for the short electrical smell I had before all this happened.

 

i am glad I did have the computer and module checked out also.  Helps isolate the problem.  I am also a big preventative maintenance guy so I have factored in the above cost into to my 2018 preventative maintenance plan for the year as a way to continue the good health of my autopilot once it is fixed.

the folks at Autopilot Central are outstanding to work with by the way and I highly recommend them.

 

more to follow........