KAP140 Autopilot Pitch Fault

[Victor]

Charles,

Attached is the diagram for the cable. There is no command set, once you connect via terminal program it will display simple text user interface with all commands available.

v

Diagram

[Rick]

Attached is the Diagram for the cable. There is no command set, once you connect via terminal program it will display simple text user interface with all commands available.

The plug you will need is a Nexus U174/U - looks sort of like a stubby 1/4" audio plug with 4 connections...

[Steve]

My aircraft had recurring pitch trim failures when it was about 6 - 12 months old. Eventually, they replaced the computer with a refurbished one. Same problem reappeared about 3 months later! This time they replaced it with a new computer - no problems since then, 8 years, knock on wood.

Steve, when you say they replaced "the computer", what exactly do you mean - the KAP140 unit itself?

Yes, they replaced the KAP140 itself.

[Charles K]

Thanks !

Charles,

Attached is the diagram for the cable. There is no command set, once you connect via terminal program it will display simple text user interface with all commands available.

v

Diagram

[Lance Murray]

The KAP 140 gets it's altitude reference from the static fitting behind the Controller. It is not connected to the altitude encoder as far as I know.

[Victor]

Thats what I thought all along, but today while practicing partial panel with ADC and AHRS breakers pulled I have noticed KAP140 showing --- in place where altitude setting is displayed. So there must be some communication between G1000 and KAP140 in regards to altitude.

[Rick]

The KAP 140 gets it's altitude reference from the static fitting behind the Controller. It is not connected to the altitude encoder as far as I know.

Thats what I thought all along, but today while practicing partial panel with ADC and AHRS breakers pulled I have noticed KAP140 showing --- in place where altitude setting is displayed. So there must be some communication between G1000 and KAP140 in regards to altitude.

For sure there is a red static tube connected to the rear of the unit, but I don't know where it goes. It doesn't appear to be connected into the main static line. And the G1000 manual shows a connection between the KAP and the G1000, so it may get altitude info that way (also?), but I just don't know. I need to find my KAP docs, but I'm buried in computer failures this week and no time to look...

[Steve]

The autopilot has a Different static source than the pitot/static instruments. That is why the tubing is red. This was done to address the porpoising issue that some had. The autopilot controller also gets altitude data from the encoder (in steam gauge airframes) or from the G1000.

[Rick]

The autopilot has a Different static source than the pitot/static instruments. That is why the tubing is red. This was done to address the porpoising issue that some had. The autopilot controller also gets altitude data from the encoder (in steam gauge airframes) or from the G1000.

From the error message, then, it sounds like the problem may lie with the connection to the G1000. I'll check that, but then it may be a trip to the shop next...

Thanks for all the info and advice! I'll post the solution once I have one...

[Victor]

I found this statement in DA40 G1000 AFM supplement:

"No altitude information or altitude preselect settings are exchanged between the
autopilot and the G1000 system. Altitude and barometric setting entries must be
made separately on the G1000 and KAP 140 autopilot systems as appropriate"

so looks like they are not talking altitude at all...