Attitude Indicator: Left Wing Low

[bud9971]

Today I flew my 250 hour RV-6A with a newly installed D-10A with and EDC-10A. The D-10A replaced an electric Atitude Indicator.

One of the reasons I replaced the electric AI is because it would erroneously indicate a nose high bank in straight & level flight following a standard rate turn. Even after multiple checkouts by the manufacturer.

Interestingly, the D-10A indicates a left wing low (left bank, about 3-5 degrees) during straight and level flight, even though the ball is centered and visually the wings are parallel to the horizon. Taxiing, though, it indicates wings level.

Additionally, the magnetic compass (EDC-10) reads correctly on the ground after calibration, but in the air is off about 30 degrees East of North.

I am concerned that my problem may be caused somehow by ignition noise (one mag and one P-mag w/auto plugs and wires) since it only manifests itself when the engine is at flying power settings.

I am curious if others have seen this problem and found a solution.

Thanks,
Ben Beaird

 

[Etienne]

I found that calibrating the EDC with the engine off or at idle didn't work... Once I did the full compass swing with the engine at about 1400rpm it was much more accurate.

 

[dynonsupport]

Ben - The wing-low reading may require a trip back here to investigate. Is it the same over different power settings?

As for the calibration, you might try updating to version 4.0, which allows calibration with some additional date inputted (the "total intensity" as well as the inclination that you already use). Also, for North America, your programmed inclination should be between roughly 50 and 70 degrees in your EFIS.

Is your EDC-D10A near any other electronics, current-carrying wires, or ferrous metal (steel)? Magnetic interference can be a concern in some installations.

 

[bud9971]

After my original post I did some additional flight testing:

I disconnected the D-10A from all aircraft power sources and flew with it powered only by the internal battery. The results were good. Attitude indication was normal and heading was acccurate & consistent.

I then installed a switch that would allow me to power the D-10A from any of 3 sources: the avionics bus (it's normal source of power and the one that gave the initial problem), directly from the aircraft battery, and the internal battery. I flew again and had good results on all 3 power sources!

The cause of my original problem is unknown. I'm perplexed but I'm convinced that the D-10A and EDC-10A are operating well. They're good instuments. I think the source of the problem lies in my installation; ignition noise, electrical noise, RF, etc.

I'll do additional testing and report back.

Thanks for the comments and suggestions.

Ben Beaird
RV-6A