I am a new (1 year almost to the day) owner of Sport Cub No. 15 (the second owner of this Cub). The airplane came with a compass that was simply inaccurate. Eventually, I had a mechanic look at it last fall. After a long session attempting to re-swing it, the mechanic gave up and said the compass needed to be replaced.

At annual time this year, a different mechanic (at a CubCrafters Authorized Service Center) attempted to re-swing the compass just to make sure. Still no luck. Ordered a new compass, and before installing it, walked around the ramp with the old and new compasses in hand. The new one was generally working fine, the old one, no go. So, we knew the old one was indeed bad.

Got the new compass installed, went for a test flight, and lo and behold, the new compass suddenly looked as bad as the old one! Now it's getting interesting. Took the compass off its mount, and put it in his lap--it suddenly performed like a good new compass should. Finally determined that the airframe has actually become magnetized over time. The old compass must have been in that field for so long that it finally threw it off for good.

The mechanic is now waiting for a tool (used by CubCrafters as well) to de-magnetize the tubes in the area around the compass. Apparently, it does not throw off enough of a field to upset any other instruments or radios, at least not permanently. This is apparently a known issue, with some airframes at least, and hopefully, this will do the trick. I'll try to post some updates as I know more, and hope to post a picture of the tool itself for those that might be interested, but wanted to at least get the party started on this topic. I thought I had seen some other posts here about compass issues in the past, but couldn't seem to come across them on my search today. Maybe this will help solve issues for some other folks out there having similar problems.