magnetic compass rebuild

[Joe Curcio]

I have just finished rebuilding my mag compass, so can offer a bit
of info. The rebuild kit I bought for my Airpath (pretty standard unit
in most planes), was essentially 2 gaskets and fluid. This worked fine
for me, because my fluid has leaked out - simple.

Your compass may just need alignment. Under the compass card of my
unit, there are 2 screws. One is for East/West, the other N/S. With
a brass screwdriver (non-magnetic), find yourself a compass rows and
align away.

I have not seen any kits that replace any of the parts inside the
compass, so you may be stuck there. The new ones are fairly in-expensive
so that may be the way to go.

[Prof. David F. Rogers (Aerospace) <dfr@usna>]

In article <111...@hprnd.rose.hp.com> jo...@hprnd.rose.hp.com (Joe Curcio) writes:
!Your compass may just need alignment. Under the compass card of my
!unit, there are 2 screws. One is for East/West, the other N/S. With
!a brass screwdriver (non-magnetic), find yourself a compass rows and
!align away.
!
Check any book on marine compasses to get specific directions on realigning
a compass. This is a standard task for yachtsman.

Dave Rogers

[David E Allen]

bra...@theory.tn.cornell.edu (Moshe Braner) / 2:05 pm Feb 26, 1991 /
> I strongly recommend the Hamilton Vertical Card Compass.
> It has no liquid to leak, but is somehow damped BETTER than the standard...
> The display is a full compass rose

These are nice for looking at, but we've tried two in the Bonanza and after
a year or two (200-400 hours) they stick like crazy. Anyone else care to
comment on their "longevity"? I'm presently a strong believer in the "old,
reliable" kind of compass.

dave allen - Fly because you love it.

[Don Fraser]

David E Allen da...@col.hp.com writes
> ... [vertical card compasses] stick like crazy. Anyone else care to

> comment on their "longevity"?

I went through two Hamilton Instruments VC 100 vertical card compasses
in my Cessna 175. Each stuck after a few weeks. I am now happily
flying with a new "good old", much less expensive, reliable Airpath.

-Don Fraser D...@HUBCAP.CLEMSON.EDU

[Tom R. Myers]

> you can use a regular (steel) screwdriver, just adjust a bit, then
> take the screwdriver away to see the result, and repeat. The harder

If there's any residual magnetism in the screwdriver, and there often
is, you're making the job more difficult than it has to be. A small
residual field will turn the compass a small amount. You can buy a
plastic screwdriver/alignment tool for tv adjustments at Radio Shack
for under a buck. They work great. The residual magnetism in steel
tools comes from usage, and the original manufacturing process.

> an accurate adjustment, the engine must be running and the plane must
> be in its cruising attitude. And how do you line the plane up EXACTLY
> with the rose on the pavement?

I had an A&P friend (see below) on the ramp help line me up on the rose
early one morning. Two passes around the rose were enough to get consistant
readings. We then made a couple of runway heading passes, a couple of N-S
E-W road follows, and a VOR radial follow to do any flight attitude fine
tuning. We did this early, with glass smooth air. The whole process took
a half hour or so.

> Whether that is a LEGAL way to adjust the compass, who knows?

I traded taking the A&P up for an acro flight, for helping me swing my
compass. This worked out very well.

TRM N1005E

[Dr. Daniel R. Masys]

In article <1741...@col.hp.com> da...@col.hp.com (David E Allen) writes:
>bra...@theory.tn.cornell.edu (Moshe Braner) / 2:05 pm Feb 26, 1991 /
>> I strongly recommend the Hamilton Vertical Card Compass.
>

>These are nice for looking at, but we've tried two in the Bonanza and after
>a year or two (200-400 hours) they stick like crazy. Anyone else care to
>comment on their "longevity"?

I've had a vertical card compass in the 182 for about 18 months, so I guess
it's in the high risk period noted by Dave. However, I can say that when
I had a vacuum pump failure a couple of months ago it certainly was nice
to be able to hold a heading using a compass that looks and acts like a
directional gyro.

Dan Masys
ma...@mcs.nlm.nih.gov

[Mike Best]

I agree entirely. I have a Hamilton VC 100 on a shelf in the hangar
because it stuck on me too. Last night I couldn't even get it to
point west. It was acting more like a ouija board than a compass :)

I've put a Precision Vertical Compass in my bird and it worked very
well when I tested it in another plane (mine isn't ready yet).
My father has an Airpath in his Defiant and it works great too.
The Precision Compass lists for $238 and the Airpath lists between
$48 to $80 in Aircraft Spruce's catalogue.

The VC-100 is $169 so that makes the Airpath look pretty good.
Why do I have the Precision? It was a gift.

-Mike Best {asuvax|mcdphx}!anasaz!best

[Al Peterman]

In article <1741...@col.hp.com> da...@col.hp.com (David E Allen) writes:

>> I strongly recommend the Hamilton Vertical Card Compass.
>> It has no liquid to leak, but is somehow damped BETTER than the standard...
>

>These are nice for looking at, but we've tried two in the Bonanza and after
>a year or two (200-400 hours) they stick like crazy. Anyone else care to
>comment on their "longevity"?

We had one in our 177RG for 4 years and 1000+ hours and it was still working
perfectly. Much better than the whisky compass in turbulence. Our's was
the TSO'ed version and not cheap ($300 or so)..I really liked it.

I have found that these vertical card compasses can have problems getting
set up due to the much stronger magnets in them reacting with airframe
and engine fields..especially in older Pipers with the center window bar.

--
Alan L. Peterman (503)-684-1984 hm
a...@qiclab.scn.rain.com

[David E Allen]

Well, there are more than one vertical card compass. The kind that has been
giving me problems, now that I have access to the actual article, is a
Precision Aviation P/N H1400, TSO C7c