Lost my HSI (G1000) in IMC yesterday

[Tim]

I'm sorry, Tim - I wasn't trying to imply anything. I had just read the other thread about updating to V22, and had that in my mind (obviously something nobody would/could try on approach). It's too early in the morning for me to try to make humor. I withdraw my post!

No apology needed. I'm not very technical but trying to learn. That's why this board is so great

[Doug]

I had this happen in my DA42 and it was the Magnometer needed to be re-calibrated. It usually happened just as I was entering cloud. Have another 200hrs on it and it has not came back. Should take less than 1 hr to recalibrate.

[Tim]

Sounds like a good thing to try next time we're up at Classic Aviation.

[Rick]

Sounds like a good thing to try next time we're up at Classic Aviation.

Tim, I will make it happen this month, when they do the pitot-static check.

[Doug]

Sounds like a good thing to try next time we're up at Classic Aviation.

I may be able to locate the procedure for the recalibration, for reference only of course if you like. let me know your email.

[Tim]

Sure. Many thanks, Doug. I'll pass on to Rick who'll likely be the one at Classic in a couple of weeks getting the IFR check done as well.

tim at burlings dot org.

Thanks
Tim

[Rick]

Sounds like a good thing to try next time we're up at Classic Aviation.

I may be able to locate the procedure for the recalibration, for reference only of course if you like. let me know your email.

Thanks, Doug. I've got a copy, too - I was looking at it yesterday, and it doesn't look too difficult. Our shop says they have done it before and it takes less than an hour, so no big deal. We already have a trip scheduled anyway for the 2-year IFR pitot-static checks...

[Rick]

Today I flew up to KSHD and had the Magnetometer Recalibration done (along with some other things). The Recalibration was simple and unsatifying - after taxiing in a circle for a few minutes and following all the instructions, the G1000 says "Recalibration Complete" and that's it. But I was hopeful it would help the HDG issue.

I also decided to run the "Magnetometer Interference Test", just because it looked interesting, and the plane was on GPU power anyway for its IFR recertification (and everyone was at lunch!). Basically, the test consists of cycling power to each electrical device at specific times, while the G1000 watches the Magnetometer for interference. The test failed! It failed when I turned on the Position lights, which produced a huge "Z-axis" spike in the gauss reading. By "huge", I mean that all the other tests produced numbers like 0.1 or 0.2, and this one was 12.7! I repeated the test on just the Pos lights, and it failed again with the same reading.

So... we call Diamond Tech Support, and they said they have seen this before. In fact, they said this is why passing the Magnetometer Interference Test is not required on the DA40 - because many of them fail on the Pos lights. There is a SB on this issue, but only for the DA40F - although they said some shops have successfully applied the SB to the DA40's also. It involves relocating the Magnetometer away from the internal metal structures in the wing. It currently sits between the steel wire tray and the metal grounding straps for the control surfaces, despite Garmin's requirement that it should not be placed within 8" of any metal. Not sure what Diamond was thinking here when it choose the current location. But I'm not ready to move it yet, either - it looks like a big deal.

This theory does explain why Tim started having the HDG problem in flgiht a couple of months ago - that is exactly when he started flying with the Position lights on all the time. Before that, both of us only used them at night. I still never use them during the day, and I have never seen the HDG problem. It all makes sense now, although I'm not sure what to do about it yet. More later...

[Rick]

Would anyone be interested in running an abbreviated Magnetometer Interference Test on their G1000 DA40 and sharing the results with me? It involves powering up the G1000 for about 5 minutes or less, no movement required. If you are interested, PM me and I will send you some detailed instructions, which involves nothing more than some fancy G1000 knob-twisting and button-pushing.

I am trying to determine just how far out-of-normal our DA40 is compared to others in the fleet.

[Tim]

I had this happen in my DA42 and it was the Magnometer needed to be re-calibrated. It usually happened just as I was entering cloud. Have another 200hrs on it and it has not came back. Should take less than 1 hr to recalibrate.

Doug, this might sound like a strange question, but do you normally switch off you strobes when you enter IMC? Thanks. Tim