Intermitent AHARS magnetometer issue

Any DA40 related topics

Moderators: Rick, Lance Murray

User avatar
BRS
4 Diamonds Member
4 Diamonds Member
FIRST NAME: Brock
Aircraft: OTHER
Registration: N8QQ
Airport: W52

Posts: 313
Joined: Sun Mar 13, 2011 12:44 am
Has thanked: 31 times
Been thanked: 94 times

Intermitent AHARS magnetometer issue

Post by BRS »

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?

Image

https://www.dropbox.com/s/006izzvmwihew ... -fault.jpg
40.649 Sold (Still miss the DA40 from time to time)
Fly and EAB Sportsman
User avatar
Rick
5 Diamonds Member
5 Diamonds Member
FIRST NAME: Rick
Aircraft: DA40
Registration: N171PS
Airport: KROA

Posts: 1508
Joined: Tue Jul 06, 2010 10:09 pm
Has thanked: 101 times
Been thanked: 256 times

Re: Intermitent AHARS magnetometer issue

Post by Rick »

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...
2007 DA40 XL - Roanoke, VA (KROA)
User avatar
BRS
4 Diamonds Member
4 Diamonds Member
FIRST NAME: Brock
Aircraft: OTHER
Registration: N8QQ
Airport: W52

Posts: 313
Joined: Sun Mar 13, 2011 12:44 am
Has thanked: 31 times
Been thanked: 94 times

Re: Intermitent AHARS magnetometer issue

Post by BRS »

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.
40.649 Sold (Still miss the DA40 from time to time)
Fly and EAB Sportsman
User avatar
OriensFlight
3 Diamonds Member
3 Diamonds Member
FIRST NAME: Hans
Aircraft: DA40
Registration: N556LU
Airport: KSTS

Posts: 64
Joined: Thu Mar 15, 2018 2:59 pm
Has thanked: 55 times
Been thanked: 33 times

Re: Intermitent AHARS magnetometer issue

Post by OriensFlight »

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.
Hans
N556LU / 40.763 - 2007 DA40 XL G1000 w/WAAS, SVT, TAS & ADS-B @ RAM Aviation in Santa Rosa, California
User avatar
Davestation
4 Diamonds Member
4 Diamonds Member
FIRST NAME: David
Aircraft: D-JET
Registration: NDJET
Airport: KFTW

Posts: 205
Joined: Tue Mar 12, 2019 7:49 pm
Has thanked: 80 times
Been thanked: 70 times

Re: Intermitent AHARS magnetometer issue

Post by Davestation »

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.
User avatar
Karl
4 Diamonds Member
4 Diamonds Member
FIRST NAME: Karl
Aircraft: DA40

Posts: 234
Joined: Wed Aug 04, 2010 3:58 am
Has thanked: 45 times
Been thanked: 56 times

Re: Intermitent AHARS magnetometer issue

Post by Karl »

AHRS.JPG
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?

Image

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.
User avatar
BRS
4 Diamonds Member
4 Diamonds Member
FIRST NAME: Brock
Aircraft: OTHER
Registration: N8QQ
Airport: W52

Posts: 313
Joined: Sun Mar 13, 2011 12:44 am
Has thanked: 31 times
Been thanked: 94 times

Re: Intermitent AHARS magnetometer issue

Post by BRS »

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.
40.649 Sold (Still miss the DA40 from time to time)
Fly and EAB Sportsman
User avatar
Karl
4 Diamonds Member
4 Diamonds Member
FIRST NAME: Karl
Aircraft: DA40

Posts: 234
Joined: Wed Aug 04, 2010 3:58 am
Has thanked: 45 times
Been thanked: 56 times

Re: Intermitent AHARS magnetometer issue

Post by Karl »

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.
User avatar
Donut
1 Diamond Member
1 Diamond Member
FIRST NAME: Nathan
Aircraft: DA40
Registration: N789VV
Airport: KDAB

Posts: 3
Joined: Wed Nov 13, 2019 4:18 am
Has thanked: 1 time

Re: Intermitent AHARS magnetometer issue

Post by Donut »

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.
User avatar
OriensFlight
3 Diamonds Member
3 Diamonds Member
FIRST NAME: Hans
Aircraft: DA40
Registration: N556LU
Airport: KSTS

Posts: 64
Joined: Thu Mar 15, 2018 2:59 pm
Has thanked: 55 times
Been thanked: 33 times

Re: Intermitent AHARS magnetometer issue

Post by OriensFlight »

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.
Hans
N556LU / 40.763 - 2007 DA40 XL G1000 w/WAAS, SVT, TAS & ADS-B @ RAM Aviation in Santa Rosa, California
Post Reply