Intermitent AHARS magnetometer issue

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yl472401
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Re: Intermitent AHARS magnetometer issue

Post by yl472401 »

Quick update on my Diamond heading issue: the Roll mode won’t be able to active during the FD AP model with airplane strictly point to the direction that set up by the FD when AP is activated ( Altitude maintained, the roll mode won’t be able to maintain as FD indicated). But I’ve noticed that the airplane will do a slight CC turn under FD mode ( probably due to lost of HDG reference and lack of capability of roll adjustment to correct the yaw caused by the nose wheel?!).

The Lost HDG Symptom is repeatable: have heading indication while taxing on the ground, but will soon lose the HDG after the airplane is in the air for about a minute. The HDG will come back soon as the plane touch the ground and will get x’d out as soon as the airplane stopped moving.
The service center called Garmin and Garmin folks mentioned the recalibration is not needed when new unit is installed( Which contravenes with the Garmin Manuel ). Ordered a new GMU and hopefully will receive it soon and do a quick swap and hope it will solve the problem.

The grounding issue would be something to look at if the new GMU doesn’t solve the issue


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Rich
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Re: Intermitent AHARS magnetometer issue

Post by Rich »

Just a thought: Check ground connection between the right wingtip fairing and the wing, as well as within the wingtip itself.
2002 DA40-180: MT, PowerFlow, 530W/430W, KAP140, ext. baggage, 1090 ES out, 2646 MTOW, 40gal., Surefly, Flightstream 210, Orion 600 LED, XeVision, Aspen E5
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Re: Intermitent AHARS magnetometer issue

Post by yl472401 »

Rich wrote:Just a thought: Check ground connection between the right wingtip fairing and the wing, as well as within the wingtip itself.
Is this something I can do without going to the shop. Would like to have some detailed info :D
Thanks.


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Re: Intermitent AHARS magnetometer issue

Post by Rich »

yl472401 wrote:
Tue Aug 24, 2021 11:57 pm
Rich wrote:Just a thought: Check ground connection between the right wingtip fairing and the wing, as well as within the wingtip itself.
Is this something I can do without going to the shop. Would like to have some detailed info :D
Thanks.


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Crude checks but

First attach a DMM to measure resistance between the tiedown ring and the housing of the nav/collision light shell. It should be zero ohms and remain so when wiggling the wingtip. Then I'd loosen all the screws and retry. Then remove the wingtip and look for corrosion on the ground connection point (the inner edge of the wingtip wire tube) and its mate in the wing. There are also three small screws that anchor the grounding strap that tube connects to in the tip of the wing to the wing structure. Look for corrosion and measure resistance between those screws and the strap. If you still have the original strobes check the grounding between the ballast chassis and the strap. Also check the resistance between the static discharge wicks in the wingtip and the grounding tube.
2002 DA40-180: MT, PowerFlow, 530W/430W, KAP140, ext. baggage, 1090 ES out, 2646 MTOW, 40gal., Surefly, Flightstream 210, Orion 600 LED, XeVision, Aspen E5
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Re: Intermitent AHARS magnetometer issue

Post by yl472401 »

Rich wrote:
yl472401 wrote:
Tue Aug 24, 2021 11:57 pm
Rich wrote:Just a thought: Check ground connection between the right wingtip fairing and the wing, as well as within the wingtip itself.
Is this something I can do without going to the shop. Would like to have some detailed info :D
Thanks.


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Crude checks but

First attach a DMM to measure resistance between the tiedown ring and the housing of the nav/collision light shell. It should be zero ohms and remain so when wiggling the wingtip. Then I'd loosen all the screws and retry. Then remove the wingtip and look for corrosion on the ground connection point (the inner edge of the wingtip wire tube) and its mate in the wing. There are also three small screws that anchor the grounding strap that tube connects to in the tip of the wing to the wing structure. Look for corrosion and measure resistance between those screws and the strap. If you still have the original strobes check the grounding between the ballast chassis and the strap. Also check the resistance between the static discharge wicks in the wingtip and the grounding tube.
Thanks for the information!!!


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Re: Intermitent AHARS magnetometer issue

Post by Rich »

Also, while 91.209 requires the strobe lights be turned on when the aircraft is in operation, you might check to see whether having them (and position lights) off improves the situation.
2002 DA40-180: MT, PowerFlow, 530W/430W, KAP140, ext. baggage, 1090 ES out, 2646 MTOW, 40gal., Surefly, Flightstream 210, Orion 600 LED, XeVision, Aspen E5
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Re: Intermitent AHARS magnetometer issue

Post by yl472401 »

Quick update on the GMU and HDG issue with a new GMU44 installed.
With the new GMU44 swapped out, the heading on the MFD and traffic information regained, Autopilot function restored as it will take the airplane to the destination as it did before, which is a big relieve on the flight safety (before the GMU44 swapping, the AP can only do pitch and roll model during AP flight.
New problem, ARHS including turn coordinator got crossed out. New error message says: GRS1 software mismatch, communication halted; 2 traffic device failed; 3 A data path has failed
From the system boot section, system says GDL 90 fail
Any thoughts?
P.S. I tried to use the three SD cards that came with the aircraft to reload the configuration without success.
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Re: Intermitent AHARS magnetometer issue

Post by pietromarx »

This is strange and I would closely question your avionics shop as to whether they did a partial update or none at all when they did the software installation.

Your avionics shop needs to do a firmware update (or, less likely, an IGS map update) on the GRS. This is a part of the GIA-63 unit. All of the software on all of the boxes has to be coordinated. You cannot update one piece to a newer revision without running into interoperability issues.

This is why you're seeing a mismatch error on the GRS and then the fail message on the "GDL-90" (which is likely the GTX345 ADS-B unit aliased as the older GDL-90 unit for compatability) not working.

It shouldn't be a big deal. You can't do it unless you have access to Garmin's firmware download site.
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Re: Intermitent AHARS magnetometer issue

Post by yl472401 »

pietromarx wrote:This is strange and I would closely question your avionics shop as to whether they did a partial update or none at all when they did the software installation.

Your avionics shop needs to do a firmware update (or, less likely, an IGS map update) on the GRS. This is a part of the GIA-63 unit. All of the software on all of the boxes has to be coordinated. You cannot update one piece to a newer revision without running into interoperability issues.

This is why you're seeing a mismatch error on the GRS and then the fail message on the "GDL-90" (which is likely the GTX345 ADS-B unit aliased as the older GDL-90 unit for compatability) not working.

It shouldn't be a big deal. You can't do it unless you have access to Garmin's firmware download site.
Thanks for the info. I talked to the shop and another avionics shop. Seems like that’s the problem. Hope they can figure things out.
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