On Sat, 12 Apr 2008 22:22:43 +0800, Stealth Pilot
wrote:

On Fri, 11 Apr 2008 19:45:50 -0700, Road Dog
wrote:

I took my Piper Warrior in for its annual and the mechanic
said that the compass card was missing and that he'd have
to swing the plane to generate a new one.

After swinging it, he claimed that he couldn't get the
E-W deviation within the minimum. So he suggested we
try "mu" shield (or something) to block the source of
magnetism which he claims is coming from one of the
instruments. (He says the compass works fine outside
the plane.)

Note: The instruments are all original, stock. Nothing
has been changed (except a radio was added which he says
is not the source.)

The mu shield fails too. He says the next thing to try is
to move the compass up to between the visors.

He says he has spent 3 hours on this so far. I'm beginning to
wonder, shouldn't a mechanic be able calibrate a compass
in a stock Piper after 3 hours ? Is he incompetent ?
Padding the bill ? Or does this really take this long ?

He has inspected and fixed everything else. Do you think
its reasonable at this time to ask him to sign off
everything else, and take the plane somewhere else where,
presumably, they know how to calibrate a compass ?

the problem doesnt seem to be the compass but some stray magnetism in
the aircraft.
swinging a compass takes about 15 minutes.

Swinging a compass in 15 minutes may be possible if no corrections are
needed but to create a new card properly requires 8 points instead of
just 4. chasing stray magnetism can take up a lot of time. Unless you
have other reasons to believe that your mechanic is incompetent or
trying to screw you then I'd be inclinded to trust him.