Cessna 120-140 Association

I’m curious where people have ended up mounting their compasses over the years. My airplane has an air path compass mounted in the panel and while it swings freely that’s about all it does. I’d like something a bit more functional, is there a recommended way to degauss the panel and leave it there or would elsewhere be more appropriate?

Compass? You mean you actually look at the compass

Mine is on the top of the glare shield in a right-angle bracket. At some point in the past someone changed my panel to one from an early 150.

6643 wrote: ↑Thu Oct 24, 2019 6:13 am Mine is on the top of the glare shield in a right-angle bracket. At some point in the past someone changed my panel to one from an early 150.

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Ditto: I have a Precision Vertical Card compass and it's on top of the glareshield.

That being said, if you have an original Airpath, they were all installed inside the panel and worked quite well. I'm not sure why yours spins. I would be looking at what electrical equipment is mounted nearby or behind the unit.

Don't laugh but I've seen it happen!

Does it have fluid in it? No fluid to dampen the card and they can spin easily!!!

Thanks for the suggestions so far. My compass does have full fluid in it, it just isn’t accurate at all (certainly well beyond the 10 deg tolerance a “good” compass should have).

What would be the best way to go through the panel and see what part is causing the most interference?

Did anyone try to swing the compass? If the errors are constant, that might be all you need. If the errors vary then look for something electrical or something that moves.

8451 wrote: ↑Mon Oct 28, 2019 9:41 am Thanks for the suggestions so far. My compass does have full fluid in it, it just isn’t accurate at all (certainly well beyond the 10 deg tolerance a “good” compass should have).

What would be the best way to go through the panel and see what part is causing the most interference?

Out of curiosity, how far off is your compass? Mine's usually around 30 degrees off until I turn on the alternator, then it's 40 degrees off. I have the Plane Power Alternator, BTW. I'm going to try to swing mine this weekend, see if I can get it closer. Not sure how close I'm gonna get though with that much deviation.

hotrodmac wrote: ↑Fri Nov 01, 2019 7:02 pm

8451 wrote: ↑Mon Oct 28, 2019 9:41 am Thanks for the suggestions so far. My compass does have full fluid in it, it just isn’t accurate at all (certainly well beyond the 10 deg tolerance a “good” compass should have).

What would be the best way to go through the panel and see what part is causing the most interference?

Out of curiosity, how far off is your compass? Mine's usually around 30 degrees off until I turn on the alternator, then it's 40 degrees off. I have the Plane Power Alternator, BTW. I'm going to try to swing mine this weekend, see if I can get it closer. Not sure how close I'm gonna get though with that much deviation.

30-40 degrees sounds about right, although I haven’t really checked beyond glancing and knowing it was far enough off to not bother trying.

Of course, you have a compass deviation card that reflects all these errors, because, otherwise, the aircraft would not be airworthy...