the ugly truth
ok, I'll bite.
from talking to many EAB flyers; the straw poll looks like this.....
1. don't even bother
2. do it in flight
3. do it on a compass rose, with everything off.....then compare to GPS in flight, calm day, fly over known surface grid
if it ain't broke, don't fix it.
sadly, one of the compass rose's within 100 miles had a fuel tank put almost on top of it. probly no effect tho', right?
ever read the specs for an engineered 'rose'?
brass rebar, buried in the concrete slab, 400 yards from the nearest electric conduit or metallic object, radio source, or Tim Hortons?
sorry, was that helpful? I don't mean to say I take it lightly....just.....well......
I've done mine on the ramp with a good compass taped to the wing, and a plumb-bob water bottle dangling from the tailhook, really helps the alignment picture.
I put tape on the ground when oriented N S E W, and then checked on repetitive rotations.
then checked on the compass rose
then in flight
absolutely, positively, nailed it accurately, + or - the mandated 10 degrees, every time.
http://www.faa-aircraft-certification.com/compass-swing-requirements.html
sorry, unable to find the same thing on the Transport Canada site after searching for an hour!