What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Compass issue

wnplt

Well Known Member
Please help I’m completely confused! A few years ago I installed a SIRS compass in my panel and has been working great. A couple months ago I sent off my right advanced flight 4500 screen to have the SD card reader replaced because it was intermittent. I received it back and reinstalled and now my compass is way off and won’t swing or even react really much at all in flight. So I thought that is strange. I call advanced flight and they say nothing should have changed. So I swapped the left screen to the position of the right and compass still is off so both displays cause the compass to be off. I take the compass out of the panel and it’s correct. I put it back in the panel and its way off again. I take the screen out and the compass is normal. I try a new sirs compass and it reacts the same as my existing compass. So both screens make the compass messed up. This is with no power and screens not even powered up. Powering up does not change a thing. Any ideas? How can the compass work beautifully for 3 years and the only thing I do is have a sd card reader replaced and now the compass and even a replacement compass doesn’t work. I thought maybe my screen got magnetized but both screens do the same. I even checked for steel screws on the screens case but found none. Pictures show what used to be the correct heading before I sent off the screen and what it shows after. The 155 heading pictures are the correct headings. The 245 heading is after the screen repair and reinstall. I did try to swing it again but it won’t. Please help…
 

Attachments

  • E3FB0A1E-F271-47C1-A34F-B7AEECEC5E02.jpg
    E3FB0A1E-F271-47C1-A34F-B7AEECEC5E02.jpg
    133.2 KB · Views: 69
  • C0D0B11B-1C32-41A4-B599-8CFA14148C11.jpeg
    C0D0B11B-1C32-41A4-B599-8CFA14148C11.jpeg
    400 KB · Views: 92
  • 1F0C43E8-C694-4BA0-ABAA-7B3F70C5B696.jpg
    1F0C43E8-C694-4BA0-ABAA-7B3F70C5B696.jpg
    174.4 KB · Views: 105
I guess it's an obvious statement, but you've got something magnetic affecting the compass. If you have a small "hiking" compass, bring it near the place your SIRS is installed and see if it changes. I've got a compass in my panel, and it's frankly not very accurate, even though there is not much magnetic near it. The panel is just a bad place for a compass.

Another idea - did you perhaps have some of that magnetic protection near your compass that might have fallen off?

https://www.aircraftspruce.com/catalog/inpages/magneticcompassshield.php
 
I tried that film and it did not work. Surprisingly the sirs compass has been perfectly accurate in the panel the last 3 years. Only thing that changed was sending off the right screen. The left screen that was not sent off affects the compass also. So weird…
 
Did you use the same mounting screws as before? I wonder if they're magnetized.

They are built into the screen. As far as the compass screws they are brass. I thought of that but the mounting screws in the display are not magnetic.
 
If the screen screws are steel and you ised a magnetic screwdriver, that could be a problem. Does the compass work with the screen out the panel?
 
Are you testing the compass outside of the hangar?

Carl

Yes it’s correct outside the hangar and really inside. It’s also correct when I pull the screen out. It had to do with sending the screen off for repair. However my left screen has never been sent off and it interferes with the compass the same. I wonder if the previous owner deguassed the screen at some point.
 
If the screen screws are steel and you ised a magnetic screwdriver, that could be a problem. Does the compass work with the screen out the panel?

Yes but the left screen installed in the hole next to the compass throws it off to. That screen is reacting the same as the right screen.
 
... If you have a small "hiking" compass, bring it near...

I think that’s a good idea. Since you said your panel compass works when the screens are out, I’d “scan” the AFS screens with the portable compass without them installed.
 
I think that’s a good idea. Since you said your panel compass works when the screens are out, I’d “scan” the AFS screens with the portable compass without them installed.

I took the screen and compass out and the right side of screen is the worst both in and out of aircraft.
 
I do not but might look into one.

google for DIY demagnetizer or degausser. There are lots of simple remedies that work well for demagnetizing small tools. I don't know about applying it to the AFS screens though. Might want to check with the manufacturer first.
 
Do you have an old style tape-deck demagnetizer you can use on the screen ?

Please exercise caution here. In the electronics world, information is often stored in magnetic form. Running a Degausser over a $2000, sophisticated electronics device seems like a really bad idea to me. Pretty sure that will void your warranty. If I wanted to make my hard drive unreadable, a degausser would be my 2nd choice after a drill.

Larry
 
Last edited:
Please exercise caution here. In the electronics world, information is often stored in magnetic form. Running a Degausser over a $2000, sophisticated electronics device seems like a really bad idea to me. Pretty sure that will void your warranty.

Larry

+1
Really a bad idea.

In the first RV-8A I used an old school bulk tape eraser to degauss the roll bar but everything electronic was out of the plane and at a safe distance.

The next two planes only use the SkyView ADHRS for heading - so the standard calibration process eliminates such worries.

Carl
 
Please exercise caution here. In the electronics world, information is often stored in magnetic form. Running a Degausser over a $2000, sophisticated electronics device seems like a really bad idea to me. Pretty sure that will void your warranty. If I wanted to make my hard drive unreadable, a degausser would be my 2nd choice after a drill.

Larry

Check with the manufacturer. I highly doubt there's magnetic storage media in these units. But that doesn't mean something else couldn't get screwed up.

-c
 
Back
Top