Hints on refilling an Airpath compass?

markscogg · #1 11-02-2010, 03:44 PM

Anyone ever refilled an Airpath Panel mount 2 1/4 inch compass?
I have the rebuild kit from Aircraft Spruce, but no directions.

Seems pretty simple, I already have the front and rear off. Is the big screw on top the recommended fill port? Did not get a gasket for that in the kit.

I have front gaskets (2) and rear diaphragm plus fluid.

Daver · #2 11-02-2010, 05:10 PM

Its been awhile since I re-filled mine but IIRC, the big screw is where you fill it.

It was a tough screw to get loose.

Dave
-9A flying

markscogg · #3 11-02-2010, 05:33 PM

Thanks for the tip. I just found an EAA article:
http://www.eaa448.org/Downloads/EAA448May09.pdf

PCHunt · #4 11-02-2010, 06:10 PM

That's a really good article, by Gary Sobek. One thing I tried, that worked, and not mentioned in his article, was to fill up a small "tub" with the compass fluid, then submerge the entire compass in the fluid. Gets the bubbles out the easy way.

You do have to have enough fluid to do that, but the tub only has to be barely big enough to hold the compass. I re-attached the fill port while the compass was submerged.

RV6_flyer · #5 11-02-2010, 06:37 PM

Quote:

Originally Posted by PCHunt

That's a really good article, by Gary Sobek. One thing I tried, that worked, and not mentioned in his article, was to fill up a small "tub" with the compass fluid, then submerge the entire compass in the fluid. Gets the bubbles out the easy way.

You do have to have enough fluid to do that, but the tub only has to be barely big enough to hold the compass. I re-attached the fill port while the compass was submerged.

The only reason that I did not do that when I wrote the article was because I was too cheap to buy more fluid.

turbo · #6 11-03-2010, 07:31 AM

i heard of a neat trick. use Johnson's clear baby oil for the fluid. it will damping out the turning errors of a magnetic compass.

Maxgain · #7 11-07-2010, 06:55 PM

During my Air Force days we used to submerge a freshly rebuilt "whiskey compass" in a container of compass fluid with the fill port loose. We would then close the container and pull a vacuum on the vessel. After equalizing the vacuum we would tighten the fill port while still submerged. Worked on B-52s and F-4Ds that I know of.
Possibly another use for your vacuum bagging pump.

sglynn · #8 08-18-2013, 11:44 PM

How do I open the case on an airpath C3250 compass so that I can access the fill screw? It is the panel mount and doesnt have any visible cap. It is just has a rounded bulb.
Thanks

rhill · #9 08-19-2013, 12:27 AM

I like the baby oil idea, will that become to viscous in cold weather?

turbo · #10 08-19-2013, 06:52 AM

Quote:

Originally Posted by rhill

I like the baby oil idea, will that become to viscous in cold weather?

good question. will have to wait for someone to try it. i have a supply in my hangar in case i need to replace mine. also comes in handy to sooth down my girl friends sore muscles.