D180 precesion on taxi

[floydwilkes]

I have a D180 D10A and HS34 with a Garmin 430.
After software update, last year (The one with GPS groundspeed if airspeed fails, V5.1 I think) the D180 will preces in pitch and roll while taxiing. After takeoff approx 5 minutes, it appears to work correctly.
I sent the unit back to you last November. You returned it said nothing was wrong and updated software.
I had my plane apart for upgrade and did not fly again until last week.
Same problem with D180!!!
Here are my thoughts, The D180 will starup fine and will sit stationary and work fine.
Is it possible that the Garmin 430 selftest sending a Groundspeed of 150 knots is messing with the pitch and roll of the D180 as the screwup occures after the 430 starts? The D180 does give the message about GPS assist and a groundspeed of 150 knots during and shortly after the 430 starts. I have the Dynons on for engine start but turn the Garmin on after start.

Today i sat in the hangar engine not running. After the 430 selftest, the D180 did the precession thing.
The 10A works fine all the time.

Floyd Wilkes

 

[dynonsupport]

There are some situations (like when you're on the ground) when use of GPS assist isn't annunciated, but it is in fact being used. This is done to prevent nuisance messages while you're taxiing around. However, if the GPS is outputting an "erroneously" high airspeed, like it sounds like it does when its in boot/test mode, that high GPS speed will help compute an incorrect attitude solution. Note that if you have IAS, it wins, so you have to have zero airspeed and a bad GPS speed (a double failure, essentially) to end up in this scenario. If you simply click past the test screen you should see the normal attitude results you're expecting. Let us know if that doesn't solve it.

 

[lindsayj]

I'm seeing this same sort of anomaly on my D10A when I pay attention. I agree it has something to do with the Garmin Test screen and its 150 KT input. I think it really gets confused if you happen to be taxiing with the test screen on. When you leave the screen while moving, pitch and bank wobble slowly for 10 or 15 seconds I think. I'll pay closer attention and see if I can add anything...Jack L.

 

[floydwilkes]

I am sure that the problem is the Garmin boot/test but I am confused as to why the problem appears on the D180 but not the D10A that are connected by the data bus.
I would think it to be a simple software fix that if airspeed is zero and GPS goes to exactly 150, disreguard the GPS input.

Floyd Wilkes

 

[skysailor]

Does the D10A firmware version you are using have GPS Assist?

 

[floydwilkes]

Both units have the current firmware 5.3.
I have not noticed the GPS assist message on the D10A.

Floyd Wilkes

 

[dynonsupport]

As mentioned previously, the GPS Assist message is surpressed at certain times to remove GPS assist nuicance alarms when you're on the ground.