GFC500 Uncommanded Go Around Mode Activated

[alextstone]

A few flights back, while the GFC500 autopilot was engaged in NAV / ALT Hold mode, it inexplicably entered GA mode.  I was flying a practice instrument approach at the time, in a descent on the GP...the fault caused the aircraft to climb straight and level in GA mode.  I took note of it but because I could not replicate it, I convinced myself that I must have bumped the GA button while making a small change in MP.  Yesterday, I was flying without the AP on and I happened to be looking at the ADI which in my plane is a GI275, and i witnessed the FD Command Bars suddenly display on the screen and the green "GA" annunciations for lateral and vertical AP states appear.  my hand was no where near the GA button.  I was in perfectly smooth air, no turbulence at all.  Even still, I disengaged the FD and  I tried to recreate the fault by bumping and wiggling the GA button.   I was unsuccessful.  Here's a photo taken after the second occurrence:

Has anyone else experienced this?  Any ideas as to root cause?  

 

Alex

'95 Bravo N1084U

[ArtVandelay]

The fault may not be the button, but the button wires even back at the GFC 507 controller. I would try to visually check the entire length of wires.

[7.Mooney.Driver.0]

We seen this before, this is due to improper wiring. Some installers are very very sloppy when it comes to crimping pins. Have a knowledgeable shop or installer verify the wiring at the GMC 500 connector and at the switch itself.




Sent from my iPhone using Tapatalk

[alextstone]

We seen this before, this is due to improper wiring. Some installers are very very sloppy when it comes to crimping pins. Have a knowledgeable shop or installer verify the wiring at the GMC 500 connector and at the switch itself.




Sent from my iPhone using Tapatalk

Thank you for the detailed info and for the photo!

Sent from my Pixel 7 Pro using Tapatalk

[PeteMc]

Just to toss this out there and there is another thread on this....

If the GFC500 looses GPS data, it will go into level flight mode (forget the actual term).  So it still could be a connector/pin issue, but loss of GPS signal may have been your issue.

 

[alextstone]

40 minutes ago, PeteMc said:

Just to toss this out there and there is another thread on this....

If the GFC500 looses GPS data, it will go into level flight mode (forget the actual term).  So it still could be a connector/pin issue, but loss of GPS signal may have been your issue.

 

Thanks but It did not go into PIT/ROL mode as would be the case with GPS outage...It went into GA mode but did not engage as the AP was not active at the time