Inaccurate wind information and heading.

[waveflyer]

I have had odd occasions when I have suspected the wind information is not accurate but never been certain.
I have just installed the new software.
On my last flight, following the magenta line on autopilot  which was in almost still air and confirmed by weather reports and smoke from ground fires, I was getting readings showing as much as 50Kt crosswind and the heading of the aircraft was way outside the boxes (highway in the sky).
The aircraft appeared to be flying straight to the target and not with the offset shown on the screen.
At other stages in the flight the wind was showing "calm variable" or something similar and the aircraft was hitting the centre of the boxes.
Where do I start looking please?

 

[dlloyd]

Unless you have done the compass calibration, your wind calculations and headings will be off. Possibly way off.

 

[dynonsupport]

Given that you describe that it works sometimes, and not others, this sounds like your compass is accurate at times, and not at others.

Generally if this happens it's due to aircraft configuration, either mechanical or electrical. Your best bet is to park the plane on the ground, and move everything you move in flight. Flaps, ailerons, rudder, throttle, etc. Then turn switches on and off. Likely one of these will cause the heading to move, and if it does, you need to figure out why this is causing magnetic distortion near the ADAHRS (which has the compass sensor inside).

 

[dlloyd]

What Dynon says. I realized the slack shoulder harness cable in an empty passenger seat would be near enough the adahrs to cause a compass deflection versus a tight harness being worn.

 

[waveflyer]

Thanks for the ideas. The ADAHRS units are mounted in the back end just in front of the elevator.
I will try what you suggest. 

 

[waveflyer]

I have tried all of the controls and switches in different configurations and it has made no difference to the DYNON compass reading apart from the strobes that deflected the reading by one degree. So it appears there is no problem in that regard.
I then calibrated the compass on the ground, went flying, calibrated it in the air and got readings in the green over 100 on both units.
Tried a few runs with the AP and everything now appears to be as it should.
Thanks, as always, for your help and input.
One snag remains (I have two ADAHRS units).
As soon as I land a message comes up on the screen. EDIT The exact words "ADAHRS CROSS CHECK ERROR(S) HORIZON RECOVERING"
Two questions.
1. How do I fix that?
2. Does this message only appear when the aircraft detects you have landed so that you are not distracted in flight?
Just by way of explanation, I'm not a techy, I didn't build the aircraft and I am very grateful for the friendly input from this forum. I hope I don't wear out my welcome.

 

[Dynon]

You'll see that message whether you're in flight on not. You might pre-emptively pull up the comparison screen before you see the message so that you can better see what's going on. That's in IN-FLIGHT SETUP > ADAHRS SOURCE SELECTION > COMPARE (button on menu).

1) This message means that the ADAHRS are disagreeing in some way. So it might mean that we need to take a look at one of your ADAHRS, or it could be something else (pitot/static connectivity can cause issues that you won't notice normally if it's your other ADAHRS that's the cause)

2) No, it will fire in flight too. If you're IFR and you have disagreeing ADAHRS, you need to know that info at that moment.