AHRS Cross Check Error Turn Rate

[nigelspeedy]

I have a dual AHRS set up. On the ground (the aircraft has not yet flown) I get a AHRS Cross Check Error: Turn Rate. As the aircraft is not moving I cant see how the yaw rate or change in heading per unit time can be other than zero. When the two attitudes are displayed to check which one is in error they both look the same and correct. The AHRS are mounted on a stiff flat plate that is supported quite securely by the longerons on each side of the aircraft. Any suggestions much appreciated.
Cheers

 

[nigelspeedy]

Dynon,

Any ideas why I would get this error on the ground stationary? A possible solution?

Thanks

 

[Dynon]

When you do the compare, the thing you should look at is the turn rate bar, which the magenta bar that extends along the black background sandwiched between the round compass and it's numerical readout directly above. Does either of them show any magenta extending at rest? They shouldn't. If one does, that's the ADAHRS with an issue. If not, we may want to get a diagnostic log from you so that we can see what you're seeing.

 

[nigelspeedy]

Ok so I have looked at the turn rate bar. Neither of the AHRS show any magenta turn rate, i.e. they both indicate zero turn rate, so no discernible difference or obvious fault. Happy to send in a diagnostic file or screen shot.
One thing I was thinking may have contributed to this is that a year or so ago I hooked each AHRS up to a pitot static test rig to determine the instrument errors and cranked them up to 300 kts (in 10 kt increments) and 30,000' (in 1000' increments). I seem to recall that some time after this there was a discussion about this upsetting the calibration of the units. The aircraft has not yet flown. Any chance this is the cause? A possible solution?
Cheers

 

[Dynon]

That may indeed be the cause. However, knowing that you haven't flown, and that you did indeed do a pitot and static check without powering down - you should see the comparison error go away you actually fly. It usually takes an hour or less of flight to nullify what sounds like the touch of turn rate difference that the two ADAHRS are seeing.

 

[nigelspeedy]

Update now that I have flown the aircraft for 6 hours is that the error has not reappeared in flight, so case closed.
Regards
Nigel