KFC 150 will not engage

[AmigOne]

A friend from Argentina tells me that the KFC 150 a/p in his 1985 J model will not engage in flight and down there they can't figure out the problem. This condition just showed one day during a flight. The unit is getting power (lights on) but when he tries to engage the a/p the push button will not stay in. Has anybody with this model has experienced something similar and, if so, what was the problem?. Thanks

[Jack Burson]

I had the same problem with my KFC200 3 years ago. It was the toggle switch (not push button) to engage. The plastic part of the switch broke inside & wouldn't let the contacts meet.

I also recently had to replace a "worn out" electric trim switch on the yoke which would occasionally cause the autopilot to fail to engage. Exercising the trim switch a couple of times would alleviate the problem.

Note: Replacing the electric trim switch turned out to be difficult and expensive. It took my avionics guy about 20 phone calls to locate the right switch & when received, all the wires were different from the original. The switch was about $650 & labor almost that amount due to rewiring and testing to be sure the autopilot worked in all modes as the switch is an integral part of that system...

[gjkirsch]

Assuming the electric trim switch is not the issue, try moving the trim with the switch before the self check on the KFC150.  Also, try the manual trim wheel, if the jackscrew is overly tight, it could also be the problem.

[Mikey]

On September 2, 2013 at 2:21:21 PM, Jack Burson said:

I had the same problem with my KFC200 3 years ago. It was the toggle switch (not push button) to engage. The plastic part of the switch broke inside & wouldn't let the contacts meet.

 

I also recently had to replace a "worn out" electric trim switch on the yoke which would occasionally cause the autopilot to fail to engage. Exercising the trim switch a couple of times would alleviate the problem.

 

Note: Replacing the electric trim switch turned out to be difficult and expensive. It took my avionics guy about 20 phone calls to locate the right switch & when received, all the wires were different from the original. The switch was about $650 & labor almost that amount due to rewiring and testing to be sure the autopilot worked in all modes as the switch is an integral part of that system...

Hi Jack.

I have a KFC200 and the toggle switch to turn the autopilot ON doesn't engage all the time. It basically won't stay in the ON position. Sounds like you were having the same issue. Where did you end up getting the new switch? Thanks for the info.

[Jack Burson]

Mikey - Sorry I've not been checking this for a while.  I used Northwest Arkansas Avionics in Fort Smith, AR (KFSM).  I've had good service from them & recommend...