Compass ground calibration

[AlanR]

Hi,
I had both my whisky compass and my Skyviews calibrated today by a professional avionics company.
Using the Dynon SV wizard was straightforward enough but I now have between +1 and +3degrees error showing on the SV's in all cardinal points compared to the whisky compass which was calibrated +1/-1 degrees to the compass master used. The guy who did the calibration could only suggest I try and reorientate the ADHARS 2degrees, which will be a very fiddly job and I am concerned that I might make things worse.
So..
1. Is +1 to+3 degrees an acceptable result from the wizard when doing a ground calibration?
2. Will an in-flight calibration improve this?
3. Am I just expecting too much and this is perfectly acceptable so leave well alone?

Any other thoughts appreciated.

Alan.

 

[KRviator]

Personally, I would accept 3* if it is going to be a bear of a job working with your ADAHRS mount to realign it. Australia's Civil Aviation Safety Authority says you should not exceed 2* for a remote indicating compass that's stabilised, 5* for an remote unstabilised or a direct reading compass used as a primary, and 10* for a standby compass.

Dynon will advise if an in-flight Mag Cal will help things, but I wouldn't think it would make it any worse.

 

[jakej]

Generally, all things being equal, an inflight cal will improve things.

FWIW I aim for the mounting of ADAHRS (or Magnetometer wit legacy units) to be within .1 of a degree laterally & horizontally - not saying this is essential but I've never had a cal issue using this method 

 

[Dynon]

An in-flight cal should help. Other factors could include interference from nearby power or ferrous metal (relative to the ADARHS or magnetometer), or perhaps a calibration location or orientation that wasn't ideal (though your shop environment and pro help should have mitigated the chances of that).

 

[Garrett]

I think your splitting hairs it is hard to hand fly a couple of degree's.

 

[AlanR]

Thanks guys for the input. I think I will try the in-flight calc and then accept whatever I get. 
I accept hand flying to a couple of degrees doesn't matter but I also have autopilot to consider and in addition it will also affect the winds aloft indication I think shown on the SV.

 

[Dandmdan]

I have done the ground portion of the compass calibration on our airport compass rose and the Skyview is showing this as completed under setup. However I still am receiving the Compass Calibration Needed message. Is this because I have not done the inflight calibration or is something else going on. By the way I also have the Standby Network Error but I believe this may be the Vans wire harness issue. Thanks

 

[Dynon]

The compass calibration needed message should only fire if there isn't a calibration stored at all, so something isn't adding up here. After you completed your ground calibration, did you reach the calibration successful/completed completed page? (I forget the exact language)? Can you take a settings backup and send it to support at dynonavionics dot com with a link to this thread?

The standby network error message wouldn't affect your compass calibration issues, BUT, it means that you have a wiring issue in one of your SkyView Network harnesses that needs to be addressed (most often a broken connection in one of the SkyView Network data wires).

 

[Dandmdan]

I believe I did reach calibration successful, however I plan to recalibrate the compass as I need to do additional taxi testing anyway. (May not be right away as temps are in the 20's here in upstate NY) If I have the Compass Calibration Needed message after recalibrating how do I take a backup setting?
Also is the best way to track the Backup Network Error by going through the network status page - Setup - EMS?
Thanks

 

[Raymo]

I skipped the ground calibration and did it in the air on my 3rd flight. Also did the AOA calibration afterward.

 

[ned]

I skipped the ground calibration and did it in the air on my 3rd flight. Also did the AOA calibration afterward.

How did you eliminate the compass calibration alarm?

 

[Raymo]

I skipped the ground calibration and did it in the air on my 3rd flight. Also did the AOA calibration afterward.

How did you eliminate the compass calibration alarm?

The warning went away after performing the in-flight calibration. I do not recall hearing an alarm but had a high fuel warning while in flight that I could barely hear. Once back on the ground, I adjusted the volume in setup from 65 to 85 so I could hear them in flight.

 

[Dynon]

Dan - Yes, just do a settings export under the load file menu to save all of your settings/calibrations to a USB stick.

As for the Backup Network Error: Yes, use the SETUP MENU > SYSTEM SETUP > SKYVIEW NETWORK SETUP > NETWORK STATUS to see what module(s) and wires (it identifies the pins) are having issues. There's also a section in the installation manual (page 21-7 in the current one) that speaks to how to use this page as a diagnostics tool.

 

[Pilotlight11]

I'm getting to this thread late, but tried to do a re-calibration today and had no luck. I drew a 10' compass rose on our asphalt and laid out the 4 cardinal points.

However, the calibration screen kept telling me I already had data stored. Yes I had calibrated it before, but I know there is something wrong when I get the following on the display:

GPS TRACK MAG Heading
006 320
092 181
184 224
267 266


What do I need to do for it to start over and accept a new calibration? I remember the first time it took some time to accept each setting and then at the end you had to push "save". "save" does not even show up and when I push each of the four direction buttons it goes blank (or blinks) and then comes back on.

I have done some work under the hood, but did not move the
ADAHRS.

Thanks

 

[Raymo]

Do an in-air calibration with someone riding along to keep their eyes outside and fly while you go through the steps.

 

[Dynon]

Bob - Once you're in the compass calibration menu, pressing DEFAULT resets the calibration if there is one stored. Starting a new calibration by pressing the NORTH, SOUTH, EAST, WEST buttons - and waiting while it collects data for each direction - should still work though even if you don't do that. Once you push one of those four directional buttons to take data, you should see a line on the bottom right side of the instruction/status page on the right indicating that the process is collecting data for that direction. That takes 15-30 seconds per direction, and you should see a percentage counter increase from 1-100% while it does that.

If the location that you happen to be calibrating has magnetic interference and isn't known to be a magnetically "clean" location, that can affect performance. Where is the ADAHRS installed in the aircraft? Has it previously had a "good" calibration that has been better than what you're seeing here?