KAP 140 GPS tracking failure

[hookem80]

My 2004 G1000 DA40 has developed a strange problem with the KAP 140; it will not hold NAV mode when the source is the GPS receiver. I have verified this both on a course direct to an airport and on a GPS approach. The NAV light or the APR light starts flashing after holding the course for some period of time. The airplane starts wandering off the GPS course after the flasing AP indication.

The problems started during a 2 hour X/C flight two days earlier. My G1000 HDG/DG went to RED X and failed for several minutes at 7500 ft, then a few min later the AP kicked off and gave me six dashes. I pulled the AP breaker and then reset the AP, after the self test the 6 dashes came back and the AP would not engage. After about 5 minutes the dashes went away and the AP worked reliably for the remander of the trip approx 20 minutes ( and the G1000 HDG or DG came back and stayed on)

Two days later, I test flew the airplane and verified that the AP will reliably track, HDG, VORs and LOC/ILS without failing. The KAP 140 passed the power on self test approx 7 times yesterday during the course of flying the airplane. The HDG/DG stayed on for the entire 1.5 hours of flight time. The only trouble noted was the AP - GPS tracking failure.

Anyone have ideas as to the cause of the failure mode we are experiencing?

Trey
N22QQ
KFTW/ KGDJ

[Rich]

Sort of, several years ago. I would try pulling the KFC140 (the actual box) and reseating. That cured it for me when it occurred.