Auto pilot

[Top Heavy]

I have a KC 150  auto pilot with altitude pre select in my 92' Mooney Bravo. Frequently, during preflight when I hit the trim test switch, it will not "test out". I do know that the disconnect yoke switch has been a source of this problem for others? Eventually, after repetitive attempts  during flight( including pulling the circuit breaker for the auto pilot), it will work.

I welcome any thoughts as to how to reconcile this intermittent problem 

  

 

 

 

[flyboy0681]

This happens to me a few times a year with the KAP 150 so I'll be watching the responses.

[carusoam]

Have you hit the obvious points?

1) cleaning contact points.

2) contacting AP Central.

Best regards,

-a-

[Alan Fox]

Just make sure that you know where the trim disconnect is , If it runs away , you may be strong enough to hold it for maybe ten minutes.....If it is frayed wires coming off of the yokeshaft , it is possible for it to runaway......best to pull the breaker until you diagnose it...

[Awful_Charlie]

I understand it is normally the trim servo that causes the KAP150 to fail the self test. I also hear that the yoke disconnect switch if sometimes the cause of the problem, and 1) they are expensive, and 2) not really rated for the current they have to handle, consequently I'll normally use the button on the unit to disconnect

[flyboy0681]

I understand it is normally the trim servo that causes the KAP150 to fail the self test. I also hear that the yoke disconnect switch if sometimes the cause of the problem, and 1) they are expensive, and 2) not really rated for the current they have to handle, consequently I'll normally use the button on the unit to disconnect

If his issue is the same as mine, pressing the Test button results in nothing. No failures, no beeping - nothing.

[Danb]

Take Alan seriously, I had runaway trim on a few occasions with my Kap 150, once at night in IFR..plane was only 9 months old, they never found the problem.

[flyboy0681]

Take Alan seriously, I had runaway trim on a few occasions with my Kap 150, once at night in IFR..plane was only 9 months old, they never found the problem.

I wrote about my harrowing experience here two years ago. Turned out to be the thumb switch was sticking in the nose down position.

[Tony Armour]

On November 1, 2015 at 6:28:37 PM, Top Heavy said:

I have a KC 150  auto pilot with altitude pre select in my 92' Mooney Bravo. Frequently, during preflight when I hit the trim test switch, it will not "test out". I do know that the disconnect yoke switch has been a source of this problem for others? Eventually, after repetitive attempts  during flight( including pulling the circuit breaker for the auto pilot), it will work.

I welcome any thoughts as to how to reconcile this intermittent problem 

  

 

 

 

Before doing your test, just barely/gently try to move the trim wheel. If it doesn't move easily like it should don't move it and see if it fails the test. If it fails, then move the trim wheel manually and try the test again. I forget everything about how it works but there is a part that works via magnet and sometimes the arm doesn't let go. A possible fix may be as simple as a piece of electrical tape to calm down the magnetic part. That's the best way I can explain it but if that test works the same for you, I can find out more. Mine gave fits for a few flights and I figured out the trim wheel work/not work deal. When the trim wheel was "stuck" I would manually move it and the autopilot would test fine. We never did the tape because it just quit...not working :-) and has been fine since. 

[mike_elliott]

On ‎11‎/‎1‎/‎2015‎ ‎6‎:‎28‎:‎37‎, Top Heavy said:

I have a KC 150  auto pilot with altitude pre select in my 92' Mooney Bravo. Frequently, during preflight when I hit the trim test switch, it will not "test out". I do know that the disconnect yoke switch has been a source of this problem for others? Eventually, after repetitive attempts  during flight( including pulling the circuit breaker for the auto pilot), it will work.

I welcome any thoughts as to how to reconcile this intermittent problem 

  

 

 

 

Check that your yoke trim switch is not sticking on and causing it to error out. This very expensive POS switch can cause this.

[flyboy0681]

2 hours ago, mike_elliott said:

Check that your yoke trim switch is not sticking on and causing it to error out. This very expensive POS switch can cause this.

Expensive yes (mine was $1,300, installed), but it was the original one which lasted for nearly 30 years.