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Compass calibration

DeltaVee47

Active Member
Hi all
I posted this question in another thread but I think it got lost.
Anyway, I have G3X touch system with GMU22 compass in the common setup from SteinAir. Everything is working except that I cannot calibrate the magnetometer. It passes the interference test but when I swing the plane I always get a fail message that says calibration score 9%. I have tried multiple locations on the airport including our compass rose, took out all the mounting hardware in case something was magnetize, consulted with Stein and G3Xpert at Garmin without success.
Any thoughts gratefully accepted
Cheers
Greg Beckner
N557GB, now 8 hours into flight test
 
Similar situation here. I received a bad GMU-22, it never would calibrate. SteinAir sent me a replacement and it calibrated first attempt.
 
Magnetometer

Hello everyone
This an update on my compass calibration problem, still not solved.
So far I have borrowed a friends working gmu22, direct wired the gmu22 to the gsu25, moved the gmu22 to the tailcone and tried multiple places to swing the compass including grass and always get the same message at the end. Calibration 9% failed.
The G3Xperts ( I’ve worked my way through 3 now) are willing to send me a replacement GSU25 to try but doesn’t think it will work. On the other hand he doesn’t have any other recommendations either.
I called Stein who has the right attitude but his guys are stumped too.
For Walt I’ve verified tubes forward, connectors down.
So if any of the amazing builders on this site have ideas I’m all ears. I’m about ready to give Dynon a call
Thanks in advance
Greg Beckner
N557GB now 27 hours into phase 1 and going to need a working panel pretty soon.
 
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Engine running or off? Off and manually swinging plane with a helper watching the screen for stop points will help hit the gates better. Also pull the breaker on everything else in the plane so it’s just the min required items. And on a pad with no rebar if you can find one? I suppose that’s the grass....
 
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Really stupid suggestion...............

Rotate the plane the other direction on the compass rose.

(Clockwise if you were going Counter-clockwise or vice-versa)


Who knows....... :confused:
 
Manual shows rotation to right; not sure it matters, but...

32.4.5.5
Calibration Procedure D: Magnetometer Calibration

NOTE
Calibration Procedure B must be successfully completed prior to Calibration
Procedure D.
NOTE
Calibration Procedure D must be carried out at a location that is determined to be free of
magnetic disturbances, such as a compass rose. Attempting to carry out this maneuver on
a typical ramp area will not yield a successful calibration. The accuracy of the ADAHRS
cannot be guaranteed if this calibration is not performed at a magnetically clean location.
Taxi the aircraft to a site that has been determined to be free of magnetic disturbances. Ensure that there
are no nearby magnetic materials on or near the perimeter of the site. If unavoidable, maneuver the aircraft
to keep the magnetometer from passing within twenty feet (6.1 meters) of such objects. Additionally
ensure that vehicles or other aircraft are an adequate distance [forty feet (12.2 meters)] away from the
aircraft under test.
At the site, align the aircraft to a heading of magnetic north (5?). It is best to offset the aircraft position to
the left (west) of the North/South axis to allow turning clockwise around the site as indicated in
Figure 32-5.
Figure 32-5 Aircraft Alignment
 
Greg, assuming you have not already done it, I would let Garmin send a new GMU-22 and even a GSU-25 if they are willing. I understand you tried a loaner GMU-22 but I would want a fresh start. Just my opinion. Sounds like Stein did your avionics which speaks for itself.

I can?t imagine it?s an installation error since you used the recommended location and there are several examples currently flying, including mine. I did my calibration on my driveway, engine off, about 25 feet away from my hangar. Actually I was surprised it passed on the first attempt and it has been checked repeatedly since then and it?s always dead-on. All that to say it seems like you have an equipment issue versus a procedural one.

My other suggestions would be to (1) get someone else to try it...AKA fresh set of eyes, or (2) do like Tom suggests and try his place as a proven location.

Hope you can get this resolved soon.
 
Update

Hi all
This an update on my compass calibration saga.
But first, thanks to all who have tried to help.
In addition to the things mentioned in my first post I have now swapped out a new GSU25-thanks Stein! However, no joy so the unit goes back to Stein on Monday. Then we ran a separate long harness from the GSU25 to the magnetometer and set it out on the wingtip. Still failed. Tried it on grass no luck.
New guys came over and ran through everything again but still failed.
I ran my pocket compass over every inch of the plane. Turns out that every powder coated piece that vans sends you is magnetized to some degree and especially the welds. I called Vans tech support. They said well yeah, so what? I explained my problem and the guy said if those parts are the problem it?s the first time in 10000 planes. In spite of things like the gear leg being magnetic I can?t get even a wiggle on the needle of a whiskey compass at the left wing shelf much less out on the wingtip.
I?m not expecting anyone to have a miraculous cure but I did want to follow up. If/when I figure it out I?ll get back with the news.
Thanks again
Greg Beckner-relearning the joys of old time vfr navigation.
N557GB
 
Make sure that your AHRS is properly configured

Make sure that you configure the AHRS properly on the setup page. Up/Down, facing fwd or back, etc. Then run the calibration on the compass and AHRS in the prescribed order per the installation manual in the G3X
 
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