Intermitent AHARS magnetometer issue

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vontresc
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Re: Intermitent AHARS magnetometer issue

Post by vontresc »

We had issues in ours as well. Don't think we ever saw the message though.

As was mentioned before, check for any ferrous metal near the magnetometer. Inspection screws should be brass near there. In our case it was related to having the Nav lights on. with the lights on we would have issues. Switching to LED bulbs solved our magnetometer issues.

we used the drop in replacements from aero-lites

https://www.aero-lites.com/
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yl472401
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Re: Intermitent AHARS magnetometer issue

Post by yl472401 »

It happens to my Da40 two days ago and simple power off-on won’t solve the problem. Symptom happened when I first punched in the destination airport and actives the AP while plane is still on the ground. The all of a sudden received the AP disable and HDG got x’ed out. Tried pulling the jumpers and won’t solve the problem. Noticed that while airplane is on the runway, it will give the correct heading, and MFD will give air traffic in the range(ADS-B) info. But as soon as the airplane is in the air, the HDG will get X’ed out and MFD will show failure on the screen with no traffic information displayed.
I looked at the Aux info and got GMU1 and GDL90 x’d out.
The symptom is repeatable so far.
Any thoughts ?

Bryan

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OriensFlight
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Re: Intermitent AHARS magnetometer issue

Post by OriensFlight »

Bryan, I'm sorry to hear about your issue. Losing the HDG on the PFD still gives me nightmares since I struggled with this problem for quite some time. In my case, a 2007 DA40-180 XL, we were able to resolve the issue by pulling the right wing and discovering that a previous mechanic (before I purchased the aircraft) had squeezed the round metal part that connects the wing's grounding into the fuselage, thereby creating intermittent contact and allowing buildup of contamination that disrupted the grounding.

So, my symptoms: HDG was fine on ground, but as soon as we climbed out the flexing of the wings caused the grounding problems. Important to note is that this was not a structural issue where the wing could have come off, it was just the grounding connection. Sadly, I went through an unnecessary Magnetometer replacement, several unsuccessful calibration procedures, many flights to my MX shop before we figured it out. It's possible that I'm the only Diamond owner who ever experienced this, but I am aware that some Diamond owners will add extra grounding straps at that fuselage/wing connection in order to improve the ground. Frankly, it seems to me like a poor design.

Note: When we talk about "pulling the wing" that usually involves disconnecting fuel-tanks and control rods, but if you have an experienced mechanic they may be able to simply separate the wing by a foot and check that grounding point.

Good luck. Let us know how it goes.
Hans
N556LU / 40.763 - 2007 DA40 XL G1000 w/WAAS, SVT, TAS & ADS-B @ RAM Aviation in Santa Rosa, California
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Re: Intermitent AHARS magnetometer issue

Post by OriensFlight »

Bryan, one follow-up, does the AP work in ROL mode? If yes, then this sounds similar to my issue.
Hans
N556LU / 40.763 - 2007 DA40 XL G1000 w/WAAS, SVT, TAS & ADS-B @ RAM Aviation in Santa Rosa, California
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yl472401
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Re: Intermitent AHARS magnetometer issue

Post by yl472401 »

Thanks buddy. I'll replay this info to my mechanics and have him look at it as soon as possible.
The symptom i have is very similar to what you have described especially the part that HDG works fine until after it takes off and flying in the air.

OriensFlight wrote:
Sun Aug 08, 2021 8:04 pm
Bryan, I'm sorry to hear about your issue. Losing the HDG on the PFD still gives me nightmares since I struggled with this problem for quite some time. In my case, a 2007 DA40-180 XL, we were able to resolve the issue by pulling the right wing and discovering that a previous mechanic (before I purchased the aircraft) had squeezed the round metal part that connects the wing's grounding into the fuselage, thereby creating intermittent contact and allowing buildup of contamination that disrupted the grounding.

So, my symptoms: HDG was fine on ground, but as soon as we climbed out the flexing of the wings caused the grounding problems. Important to note is that this was not a structural issue where the wing could have come off, it was just the grounding connection. Sadly, I went through an unnecessary Magnetometer replacement, several unsuccessful calibration procedures, many flights to my MX shop before we figured it out. It's possible that I'm the only Diamond owner who ever experienced this, but I am aware that some Diamond owners will add extra grounding straps at that fuselage/wing connection in order to improve the ground. Frankly, it seems to me like a poor design.

Note: When we talk about "pulling the wing" that usually involves disconnecting fuel-tanks and control rods, but if you have an experienced mechanic they may be able to simply separate the wing by a foot and check that grounding point.

Good luck. Let us know how it goes.
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Re: Intermitent AHARS magnetometer issue

Post by yl472401 »

The AP won't kick in when the HDG got crossed out. But when the HDG does display some heading reading, AP function fine and passes the Heading bug check during per-flight.


OriensFlight wrote:
Sun Aug 08, 2021 8:05 pm
Bryan, one follow-up, does the AP work in ROL mode? If yes, then this sounds similar to my issue.
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Re: Intermitent AHARS magnetometer issue

Post by OriensFlight »

Interesting. In my case, it was still possible to engage the GFC700 AP in ROL mode. HDG or NAV mode obviously didn't work. btw, at 1,000 hrs you need a bonding/grounding check, so as others have mentioned it might be possible to determine an issue with grounding via that inspection. I would warn you, however, that in my case while the plane was on the ground, with wings unloaded, it always passed grounding limits test, that's why this issue was so frustratingly intermittent.
yl472401 wrote:
Sun Aug 08, 2021 8:18 pm
The AP won't kick in when the HDG got crossed out. But when the HDG does display some heading reading, AP function fine and passes the Heading bug check during per-flight.
Hans
N556LU / 40.763 - 2007 DA40 XL G1000 w/WAAS, SVT, TAS & ADS-B @ RAM Aviation in Santa Rosa, California
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yl472401
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Re: Intermitent AHARS magnetometer issue

Post by yl472401 »

I remembered for once I'm in the air, the airplane was able to maintain altitude with the AP, but going straight forward without HDG change.

OriensFlight wrote:
Mon Aug 09, 2021 12:12 am
Interesting. In my case, it was still possible to engage the GFC700 AP in ROL mode. HDG or NAV mode obviously didn't work. btw, at 1,000 hrs you need a bonding/grounding check, so as others have mentioned it might be possible to determine an issue with grounding via that inspection. I would warn you, however, that in my case while the plane was on the ground, with wings unloaded, it always passed grounding limits test, that's why this issue was so frustratingly intermittent.
yl472401 wrote:
Sun Aug 08, 2021 8:18 pm
The AP won't kick in when the HDG got crossed out. But when the HDG does display some heading reading, AP function fine and passes the Heading bug check during per-flight.
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yl472401
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Re: Intermitent AHARS magnetometer issue

Post by yl472401 »

Looks like the three securing screw for the inspection panel and the securing screw for the wire were made of ferrous metal. I'll check today to confirm.
vontresc wrote:
Fri Jan 17, 2020 2:41 pm
We had issues in ours as well. Don't think we ever saw the message though.

As was mentioned before, check for any ferrous metal near the magnetometer. Inspection screws should be brass near there. In our case it was related to having the Nav lights on. with the lights on we would have issues. Switching to LED bulbs solved our magnetometer issues.

we used the drop in replacements from aero-lites

https://www.aero-lites.com/
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vontresc
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Re: Intermitent AHARS magnetometer issue

Post by vontresc »

Glad you figured it out.
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