KAP 150 Autopilot Issue

[togapilot]

Good evening,

KAP 150 Autopilot; It will pass the self test both on the ground and airborne. It will consistently engage in AP, ALT, HDG and NAV modes while on the ground but it will not engage in HDG or NAV while airborne. I can use AP and ALT modes while airborne. Seems odd to me that it will engage in all modes on the ground but then loses HDG and NAV only when airborne.

Any of the KAP gurus on here that might have some advice or simple troubleshooting that I can do before engaging an avionics shop for their services. 

Thanks in advance,

Jason Calloway

[carusoam]

Welcome aboard Jason…

That sounds interesting… we have a couple of AP gurus around here…

Lets invite @Jake@BevanAviation to stop by (KAP150 misbehavior)

Best regards,

-a-

[Jake@BevanAviation]

If the system will not let you select a lateral mode of operation my guess is you are loosing the compass valid input to the flight computer.

Edited April 9, 2023 by Jake@BevanAviation

[togapilot]

Thank you for the quick response Jake@BevanAviation. Are you aware of any reason that it might get a compass valid flag while on the ground but not when airborne? Also, in doing some troubleshooting today I pulled the circuit breaker for the HSI (both HDG and NAV Flags showing on the HSI) and the AP world still pass the self test and engage while on the ground. Do you think this is normal behavior?

Jason

[Jake@BevanAviation]

Without the compass valid I believe it will pass pft, but when trying to select a lateral mode it will not allow it.  With the heading flag in view it should not allow any lateral modes.  If the system is engaged in a lateral control mode and you loose the compass valid the system should disengage. It will allow you to engage with FD and a vertical mode but you will not be able to select a lateral mode.

[togapilot]

Thanks again Jake. I'm pretty sure that I can get the AP to engage in HDG and NAV modes with both the HDG and NAV flags in view on the HSI. That being said, it will only do this one the ground, not when airborne. I'll check again tomorrow as I'll be going up for a short flight.