D10A Pitch Jumping

[Tsm22]

I have a D10A with latest software, it has a GPS feed but no NAV etc…
When checking various avionics in the hangar I have found that the ‘GPS Assist’ sometimes flashes up and then the pitch will shot up 20-30 degrees. I’m not yet flying the aircraft so not sure if this will happen in flight. Seems a bit weird.

I know that there is some coupling of GPS/pitot/gyros, could a dodgy GPS signal in the hangar be causing this? If the unit thinks it is moving but speed = 0 thus looks at GPS data?

Should I turn the GPS source off and check there isn’t some other internal issue?

Thanks in advance. Tim

 

[Rhino]

The GPS isn't really coupled to the pitot or gyros. The EFIS is. When the EFIS senses zero airspeed, it assumes a failure of the pitot/static system or gyros and fails over to the GPS for attitude information as a backup. Any GPS reception inside a hangar can be spotty at best, so it probably just isn't producing good attitude data there, particularly when not moving. I wouldn't worry about it unless it happens outside.

 

[Tsm22]

Thanks for the suggestion.

 

[Dynon]

You'll see GPS assist when the EFIS doesn't have airspeed but DOES think it is moving via GPS. You can get erroneous non-zero speed when in a hangar and you're peeking in and out of a lock . So that's expected.