GI 275 Primary ADI powers the magnetometer (GMU11) from own internal battery.

[@TheHausmanns]

@Chris - This video is super helpful. I have a dual GI 275 setup in my Mooney. I had an alternator fail (and become intermittent) on a flight... luckily in day VFR. At some point after the alternator died, the GMU 11 lost its heading indication. When it came back (intermittently with the alternator I suspect), the heading read 30 degrees to the left. After that I was back to my wet compass for backup heading. I am trying to figure out (a) why would the GMU 11 fail with the alternator (if I still had battery charge --maybe voltage was too low), and (b) more worrisome...why would it fail to the wrong heading. Any thoughts?

[@chriskoppel3940]

You describe a definitely odd scenario! The only way I can imagine what you describe happening is if the GMU11 is NOT connected to the GI275 ADI (top unit) as it should be, and for some really odd reason also not powered by the battery when the alternator fails. Why would it come back up with a 30 deg error is also baffling unless alternator was not providing adequate consistent power to it. REALLY ODD!!!!

[@VusaMoyo]

Hi Chris, so why is it not displaying its internal fed heading? Does it require movement?

[@chriskoppel3940]

I am not sure what you mean by "internal fed" heading. Do you mean the internal VFR GPS track?

[@VusaMoyo]

@@chriskoppel3940 I suppose. I'm guessing its fed from your GPS unit?

[@chriskoppel3940]

OK. Good question. It is because the GI 275 VFR GPS will only activate after it has first seen a panel mounted GPS and then having the panel mount GPS fail (signal go offline). It will not activate if it is the first GPS to come online. It is not "either or" logic giving the panel mount priority. Instead it is a panel mount GPS failure flag that activates it. Could potentially be an issue in certain scenarios.

[@VusaMoyo]

@@chriskoppel3940 Thanks. It is something to ponder w.r.t failure scenarios. My GI275s (dual setup) are being installed this week. The primary will be connected to the magnetometer as well as to the GFC500 & 430, with the secondary acting as a MFD/Standby - similar to your setup.

[@chriskoppel3940]

Enjoy your setup!! Great instruments.