Brian Whatcott
November 8th 09, 04:14 PM
The Airpath compass is meant to work in a fluid
filled chamber.
A bubble is an annoyance. A leak leaves you with a
trembling indicator that won't indicate a heading
with any reliability.
Gasket and fluid kits are not that high.
From Chief etc. $20-$30
If caught short, don't try making a rear
diaphragm from a truck inner tube, and refilling
with lamp oil. The oil swells the diaphragm, and a
week later, it's leaking again.
The construction is a cast barrel with a front
gasketed glass, and a rear rubber diaphragm.
The glass face can be chipped by too enthusiastic
attempts to lift it out.
It's helpful to use a little gasket
cement on the front and back gaskets.
The filler screw has a sealing washer.It's best
filled with a throw-away syringe.
Fill to the top. Screw closed.
Turn several ways. Look for the air bubble.
Repeat. Three or four times. You finally get lucky,
with no bubble at all.
Leave it standing face down overnight, and look
for sweating. If you see any sweating, you still
have a leak.
The glass face is held onto its thin gasket by
a face plate with a cork gasket under it.
You snug the face plate down but don't over tighten,
else the inner gasket can squeeze out.
Even worse, watch out for the cover plate screws
on the adjusting magnets.
If these screws are too long, they force the face
plate away from the glass, and...it leaks again.
If the worse comes to the worst - a replacement
unit is $110-$130 from the aero suppliers.
Brian Whatcott
filled chamber.
A bubble is an annoyance. A leak leaves you with a
trembling indicator that won't indicate a heading
with any reliability.
Gasket and fluid kits are not that high.
From Chief etc. $20-$30
If caught short, don't try making a rear
diaphragm from a truck inner tube, and refilling
with lamp oil. The oil swells the diaphragm, and a
week later, it's leaking again.
The construction is a cast barrel with a front
gasketed glass, and a rear rubber diaphragm.
The glass face can be chipped by too enthusiastic
attempts to lift it out.
It's helpful to use a little gasket
cement on the front and back gaskets.
The filler screw has a sealing washer.It's best
filled with a throw-away syringe.
Fill to the top. Screw closed.
Turn several ways. Look for the air bubble.
Repeat. Three or four times. You finally get lucky,
with no bubble at all.
Leave it standing face down overnight, and look
for sweating. If you see any sweating, you still
have a leak.
The glass face is held onto its thin gasket by
a face plate with a cork gasket under it.
You snug the face plate down but don't over tighten,
else the inner gasket can squeeze out.
Even worse, watch out for the cover plate screws
on the adjusting magnets.
If these screws are too long, they force the face
plate away from the glass, and...it leaks again.
If the worse comes to the worst - a replacement
unit is $110-$130 from the aero suppliers.
Brian Whatcott