GI 275 Heading Issues

[Timothy Burchett]

I have a GI 275 installed as my primary HSI. The plane just came out of Annual, and I am now getting intermittent heading failures. When indicating a heading failure, TRK is displayed. However, when HDG Failure is not indicating, the heading is off by over 60 degrees. This is a new issue that started after the annual. Is there anything I can check to try and resolve the issue before taking it to a Garmin Dealer? Thanks.

 

[WDD]

What did they do in the annual?

 

[Ryan Klems]

Do you know where your magnetometer is installed? My guess would be something that occurred in the annual either accidentally magnetized some hardware that is near the magnetometer (it doesn't take much, I've seen them thrown off by a single cad screw/nut to add an Adel clamp nearish to the magnetometer installed with a magnetic tip screwdriver, they are pretty sensitive instruments), or some sort of electrical change occurred that is interfering with the magnetometer (ground connection somewhere was disturbed leading to poor ground and higher interference, new electrical load near the magnetometer added, etc). If you know what work might have been done and where the magnetometer is installed, it might provide some sort of clue. How recently installed was the GI 275? Any operational differences? (say GI-275 was installed in the fall/winter, now it's summer, you have AC and are running it, could be generating big time interference and installer might not have properly tested all the scenarios for interference)

 

[Timothy Burchett]

What did they do in the annual?

My brake lines and cylinders were replaced because they were leaking. They also replaced my flap indicators from the old kind to the new push to test kind.

 

[Timothy Burchett]

Do you know where your magnetometer is installed? My guess would be something that occurred in the annual either accidentally magnetized some hardware that is near the magnetometer (it doesn't take much, I've seen them thrown off by a single cad screw/nut to add an Adel clamp nearish to the magnetometer installed with a magnetic tip screwdriver, they are pretty sensitive instruments), or some sort of electrical change occurred that is interfering with the magnetometer (ground connection somewhere was disturbed leading to poor ground and higher interference, new electrical load near the magnetometer added, etc). If you know what work might have been done and where the magnetometer is installed, it might provide some sort of clue. How recently installed was the GI 275? Any operational differences? (say GI-275 was installed in the fall/winter, now it's summer, you have AC and are running it, could be generating big time interference and installer might not have properly tested all the scenarios for interference)

The main change is that the flap indicating lights were upgraded since the old ones were broken, and I had the brake tubes and cylinders replaced. Would that be enough to do it? The instrument was installed three years ago and has worked in all four seasons. Nothing else changed. Would it likely just need to be re-calibrated?

 

[WDD]

How much panel disassembly did they do to change the flap lights? Something was disturbed. Also, “intermittent electrical problem” is a pain. Lose wire? Lose ground?

I think Ryan’s post is still the best answer.

Did you ask you annual guys how and where they did their work?

 

[Timothy Burchett]

How much panel disassembly did they do to change the flap lights? Something was disturbed. Also, “intermittent electrical problem” is a pain. Lose wire? Lose ground?

I think Ryan’s post is still the best answer.

Did you ask you annual guys how and where they did their work?

Think a loose connection could cause this? I plan to go in and check all the wires tomorrow morning

 

[Ed Haywood]

Think a loose connection could cause this? I plan to go in and check all the wires tomorrow morning

Whenever an electrical fault is intermittent, loose connections are a prime suspect. How else to explain it only happens sometimes, not all the time?

 

[RobMooney]

Did you ever resolve this one?