Compass Issues and Airframe Magnetization

[ceslaw]

That said, what's the harm in removing them to be safe versus the cost of replacing them?

Mike

I agree. My plan was to remove the magnetometer since it is easily accessible and no reason to take a risk.

But Dave's reference to that article suggests simply removing the compass from the wind screen solves the issue with the G3X and its magnetometer input.

Does CC still put the old compass in planes equipped with the G3X and magnetometer??

[Daveembry]

Chuck, yes my FSDO here said there was no need for it. I’ve never gotten one to work up there. Hold your compass app on your iPhone up there and see what happens as well! That’s why the magnetometer is waaaaaaay out there on the wing.

i figure the iPhone compass program would always work as a backup in case of total loss of electronics. Just have to hold it away from the tubes.

[QUOTE=ceslaw;29219]

interesting article here ?……. https://www.holladayaviation.com/ind...ic-compass-qa/


Dave:

Very interesting article indeed. As I read it, it appears the current regs require a 'magnetic direction indicator', and presumably the G3X with its magnetometer would fulfill that requirement. The regulation requiring a compass deviation card no longer exists. So the magnetic compass can simply be put back in the box and call it done.

Are we missing something? Does the G3X and its GMU-22 magnetometer indeed constitute a 'magnetic direction indicator'?

Anyone else want to chime in??

Thanks for the info.

Chuck

[ceslaw]

Just checked some additional sources. G3X with its magnetometer meets the 'magnetic direction indicator' requirement. No need for a compass on the windscreen. Problem solved.

Thanks for the good feedback.

[Andy]

Does CC still put the old compass in planes equipped with the G3X and magnetometer??

My 2020 FX-3 has a windshield mounted magnetic compass with correction card. When I have checked it against the G3X magnetic heading I have been impressed by how good the agreement is (before applying correction card offset).

[karaka29211]

As an EX2 builder I have the same issues discussed in this thread and have applied a degausser (growler) to the cockpit with little success. When removed from the aircraft, the standby compass is fine.
My questions are
Has anybody reported success with the demagnetising process?
Some websites suggest a circular motion of the growler is required.
Is it possible to retrofit stronger compensating magnets to a standby compass?
Can you confirm that close application of the "growler" to electronic panel units poses no problems?
A compass survey of closeby fuselage welds does identify particular sites of magnetisation, can experimentation or known areas produce results, say only within 2ft of the aircraft compass?
Cubcrafters covers the installation of the SIRS compass mounted on the windshield, is that any more successful than any other brand?

Two things to consider, one is that while you can remove magnetism with degaussing, you cant remove the fact that a compass is still attracted to anything with iron in it. Admittedly the fact that iron will become magnetized only makes things more complicated, but often its just the presence of iron that causes much of the problem and its pretty hard to eliminate iron from a steel tube fuselage.

We had been using an old hand held demagnetizer that came from radio shack or somewhere, its been around here forever, to degauss tubes. I forget its original purpose but essentially you plug it in, its an ac magnetic field and you run it along the tubes in question and move it away from them as you go, to gradually lessen the field strength. Sometimes you get it on the first try, other times you dont. Sometimes you swap compasses or you get one with stronger compensating magnets in the compass.

Wish I had a better outcome to the story, out of the sheer number of aircraft that go out the door we do seem to get them dialed in pretty well, just not always on the first try. I see the guy on the line still occasionally have to swap one to get one that works best.

Good luck

Mike Sutton
Cubcrafters Avionics

[ceslaw]

On the third Carbon Cub build I bought a large circular degausing device. Looks like a huge donut. Originally it would have been used on tube type color TVs. Old tech.

Spent some time with it and no success. Repeated the process several times, different technique, nothing solved the issue. I did this on the frame before mounting any avionics, engine, etc.

I also tried degausing it with a large soldering gun held an inch or so away. No success.

Ultimately this plane will have a magnetometer making a panel mounted compass unnecessary.

This was not an issue on the first Carbon Cub.

Frustrating. Wish I had a solution to suggest.

[Andy]

Frustrating. Wish I had a solution to suggest.

Maybe Pete can gives some clues about how they do it at the factory. I don't think I have ever seen more than 5 deg difference between the windshield mounted compass and the heading indicated on the GDU HSI (FX-3).

[Pete D]

Here at the factory they use a degausser similar to an old VHS tape erasure. It is a trial and error/art process of using the degausser, check, try it some more. The general idea is you aren't removing the magnetism as much as moving it around. The degausser is slid along the tube and pulled away before releasing the power. There are small round analog gauges that can measure magnetism. This effort is usually focused in the upper/forward cabin area where the compass is mounted.