KAP150 Autopilot/servo repair

[Jake@BevanAviation]

@bcbender10 Sounds like the voltage regulator in the trim servo has failed.  When this happens you will have no MET (manual electric trim) and the flight computer will not pass PFT.  I would suggest doing the normal power and ground checks on the servo connector and if that checks good have the trim servo bench checked.

Also, if you get no flashes of the trim annunciation during PFT that is a good indication the voltage regulator has failed. During PFT there should be 4 flashes of the trim annunciation if the systems passes you should get a flashing AP light for approximately 12-13 times.  Anything else would indicate some kind of failure detected.

One last thing, if the flight computer was manufactured within 1993-1998 those units are known to have capacitor leakage issues that will cause some weird issues.  The -15 units can only be serviced at certain shops (Mid-Continent, Duncan, Honeywell) the older -2 (14V) and -3 (28V) units can be serviced in the field if the shops have the necessary equipment and MM documentation.

KFC 150 M20jk 14-28v.pdf

Edited March 7, 2022 by Jake@BevanAviation