KAP 150 no Alt hold - post-annual

[Oldguy]

First flight after annual in N5767Z today to check everything out. She came out of annual on January 5th, but we had winter last weekend and today was my first chance to fly. Started up on 1 blade and ran great. All ground checks appeared good. New ignition harness and cap had no problem, good roll and takeoff and nice climb on a 68 degree morning. Once up, I went to engage the A/P. Heading and Nav worked fine, but no Alt hold. Light would flash once when I pressed the button, but no actual hold.

Back on the ground, I taxied over to the hangar and did the following:

Avionics switch off.

Avionics switch on.

AP test. 5 beeps with flashing AP light and 7(8?) light flashes after the beeps. Same as always.

Repeat flight. Same results.

During annual, I had my pitot/static check done and they found and repaired a hole in the static line. Before I go to the avionics guy or my MX, I wanted to pick the MS brain trust. I have read there is a document somewhere to decode the number of beeps and flashes the KAP 150 produces on the AP test. Does anyone know where I could find it? I guess it could be the computer itself, but it would seem to be a coincidence it failed like this, wouldn't it?

My plan of attack is to get info from MS, try anything recommended, talk with the avionics guy and MX if not resolved and call Autopilots Central if there is still a problem after all MS and local assistance.

Thanks for any and all help offered.

[carusoam]

I did a lot of reading but came up empty on trying to find the decoder of the beeps and lights and test functions.

While on the ground.... Check the trim functions, manually from one end to the other.  See if it has any difficulty moving..?

PP idea only, not an electronics guy or mechanic...

Good luck,

-a-

Edited January 14, 2017 by carusoam

[Oldguy]

8 minutes ago, carusoam said:

I did a lot of reading but came up empty on trying to find the decoder of the beeps and lights and test functions.

While on the ground.... Check the trim functions, manually from one end to the other.  See if it has any difficulty moving..?

PP idea only, not an electronics guy or mechanic...

Good luck,

-a-

Anthony, I tried Googling to find it as well as a MS search. Found the installation manual, but nothing in there about them either.

Good idea on the trim. I will try it this afternoon when I am back out at the hangar (nice thing about living 5 minutes from the home drome).

Thanks.

[gsxrpilot]

From the Pilots Guide for the KAP System

The KAP 150 system incorporates a system self-test function which is activated by a test button on the KC 191...
1. All annunciator lights, the trim light and autopilot light will illuminate.
2. The trim light will flash 4 times.
3. The annunciator legends will go blank, an aural tone will be (approx. 6 times) and the "AP" light will flash (approx. 12-13 times) and go off. (If the AP light fails to flash you will be unable to engage the autopilot.)
4. The KC 191 display will go blank.
CAUTION: If the trim legend flashes or remains on at the end of the test it indicates there is a failure in the trim system and the autopilot will not engage.

[Oldguy]

Update: Went back Saturday afternoon and powered up the avionics without the engine running. Did the AP test as Paul notes above (normal part of my pre-flight) and then engaged the AP while on the ground. Heading bug commanded left and right turns and when I set Alt hold, trim continued to run. DUH - ASI showing severe nose up without vacuum! Shutdown all and restarted with stand-by vac running. All tested well including Alt hold. Got my MX, went for a 20 minute flight and the thing performed perfectly. WTF,O? (Pilot talk.) Made the Sunday run to Destin for breakfast and back and it never missed a lick.

At this point, I have no idea the cause of or the resolution to the problem. It will retain a high level of attentiveness until I re-establish my trust in it. Probably fly mostly VFR for a while and run it through some various approaches.

Anthony and Paul, thanks for the suggestions and input.