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There are a number of threads on AHRS issues. However I didn't quite find anything really helpful.
Occasionally when I startup I don't have any magnetometer (no Compass) but it usually shows up upon taxi out. Then in flight I'll get the warning in the attached image. Is this a common failure mode or do I have dirty contacts someplace?



https://www.dropbox.com/s/006izzvmwihew ... -fault.jpg

Brock, I never saw that in-flight fault message, so you may have a different problem, but your startup and taxi description is exactly what I was seeing. Have you tried the magnetometer recalibration yet? I went from HDG failures during taxi on more than half my flights, to zero failures after the recalibration. It's an easy first step...

Rick wrote: ↑Sat Dec 28, 2019 2:49 pm Brock, I never saw that in-flight fault message, so you may have a different problem, but your startup and taxi description is exactly what I was seeing. Have you tried the magnetometer recalibration yet? I went from HDG failures during taxi on more than half my flights, to zero failures after the recalibration. It's an easy first step...

Rick, I've not heard about the recalibration procedure. Where can I find more information about how to do that? Thanks for the tip.

Maintenance mode, GRS, GRS/GMU Calibration. Then there are two modes under Select Procedure. One of them is Pitch / Roll Offset, the other says Magnetometer, or something.

This is something I’ve left to my mechanic, because according to the instructions from Diamond Support you have to level the aircraft for pitch / roll first, which requires putting the aircraft on jacks. Also, if you do something wrong in the MX mode you can ground your plane.

That is curious, I don't recall ever seeing the CAS message either, just the red X over HDG. Recalibration is still worth a first shot, but it may be a non-standard issue. Doing the GMU calibration without doing the pitch/roll offsets won't hurt anything, those should only need to be done on very first installation of the GRS77. There's also an engine vibration test that you could run through while you're out there, but IMO this seems like something that snuck past beta testing without being proven as useful.

Two things I always go to first - connectors and software. Not just reloading the IGRF but the G1000 software for the AHRS and specifically the GMU calibration files.

BRS wrote: ↑Sat Dec 28, 2019 3:36 am There are a number of threads on AHRS issues. However I didn't quite find anything really helpful.
Occasionally when I startup I don't have any magnetometer (no Compass) but it usually shows up upon taxi out. Then in flight I'll get the warning in the attached image. Is this a common failure mode or do I have dirty contacts someplace?



https://www.dropbox.com/s/006izzvmwihew ... -fault.jpg

This is what the fault diagnosis chart says.
I would recommend more fault diagnosis and checking out less expensive options first though.

Thanks Karl.
Interesting how they immediately go to "replace". That's a big assumption (that nothing else is wrong). Also, there is not a consideration for 'intermittent'. I've been busy so I've not yet tried to do the alignment.

BRS wrote: ↑Mon Jan 06, 2020 3:43 pm Thanks Karl.
Interesting how they immediately go to "replace". That's a big assumption (that nothing else is wrong). Also, there is not a consideration for 'intermittent'. I've been busy so I've not yet tried to do the alignment.

Just for clarification, that is the fault diagnosis chart for G1000. It is G1000 only so it does not deal with any airframe parts. Maybe this is why it doesn't go into detailed fault diagnosis. I posted as it was the only place I saw fail warning.

The magnetometer can be affected by a few things.
Aileron balance weight used to be one of them, your aircraft probably has the SB done, but might be worth checking if it was missed.
Any change of strobe or wingtip lights could affect it, especially if you have used something other than the manufacturer.
The cal procedure can help identify if it is lights related by checking the Gauss readings with lights on and off.
Not Diamond but I did see one issue similar to yours where the problem was a bad/less than ideal earth from the tip lights.
I have seen a lot of corrosion and deterioration of the bonding system on some aircraft. It can get quite serious but still just pass the bonding test. What I mean by that is serious corrosion in hidden locations that are difficult to see but passes the bonding test. So if your engineer just tests and doesn't look closely it can be missed.
All worth considering before you splash out on replacing Garmin parts.

I had the same issue that you're reporting. After trying to troubleshoot the issue for a couple days my mechanic decided the best course of action was to just replace it with a refurbished model. I can't say for sure that it couldn't have been fixed but I trusted my mechanic's opinion here and I haven't had an issue since.

I've been investigating HDG indicator failures, and after a magnetometer replacement and several recalibrations, among other things, all the signs point to grounding problems. After discussions with my mechanic, Diamond Canada and Karl, my mechanic will be pulling the wing and work to get solid grounding readings. It's a required inspection on the 1,000 hr, and my aircraft is nearly there. Diamond Canada did mention some operators install extra grounding strips between the wing and the fuselage, so I might try that as well, since the wing to fuselage ground is merely an interference fit. I'll update the thread when I learn more.