Maintenance Questions

"RST Engineering" wrote in message

Yeah, I did this whole "what fluid to use" thing about four years ago on
this same newsgroup. No, kerosene isn't the optimum choice, but that's
what Lindy had to use going across the Big Pond, and the FAA has proceeded
little from that point.

Mineral oil freezes at a fairly high temperature. Damned few sailboats
out on the water when it freezes, so that isn't a problem for them. It is
for us.

The viscous fluid of choice for compasses is copy machine fuser oil. Good
from boiling to freezing and well past. Thick enough not to ooze past
slightly dried out seals. Not to be used except in experimental aircraft
and aviation quality (ahem) "boat" compasses.

Interesting.

Is that "fuser oil" the stuff that was used in the old purple letter
mimeograph copy machines, or something in newer machines that I know
absolutely nothing about?

I always used to love that smell, of freshly run copies. So if I smelled
that wonderful smell in flight, I know my compass just sprung a leak!

What do the new compasses (those that still have magnets in them) use for
fluid?
--
Jim in NC

Morgans wrote:
"RST Engineering" wrote in message

Yeah, I did this whole "what fluid to use" thing about four years ago on
this same newsgroup. No, kerosene isn't the optimum choice, but that's
what Lindy had to use going across the Big Pond, and the FAA has proceeded
little from that point.

Mineral oil freezes at a fairly high temperature. Damned few sailboats
out on the water when it freezes, so that isn't a problem for them. It is
for us.

The viscous fluid of choice for compasses is copy machine fuser oil. Good
from boiling to freezing and well past. Thick enough not to ooze past
slightly dried out seals. Not to be used except in experimental aircraft
and aviation quality (ahem) "boat" compasses.

Interesting.

Is that "fuser oil" the stuff that was used in the old purple letter
mimeograph copy machines, or something in newer machines that I know
absolutely nothing about?

No, it's not that.

Fuser oil was used in older copy machines.
It's a clear, probably silicon-based oil
that kept the fuser rolls soft and pliable.

Haven't seen it for years.

The SIRS compasses are using a silicon fluid. The claim is that the
"thicker" fluid reduces turning and acceleration errors.

personally, I really like the big numerals on the dial!

Yes, I can actually see the numbers on my SIRS compass. I think there were
numbers on the old original one. They may even have been somewhat visible
when it was new.

"Blanche" wrote in message
...
The SIRS compasses are using a silicon fluid. The claim is that the
"thicker" fluid reduces turning and acceleration errors.

personally, I really like the big numerals on the dial!

On Jun 24, 8:34 pm, "C. Massey" wrote:
Cousin has a glider and said that he needs to add fluid in compass.

Is this something that can be done? If so, can he do it or does an A&P have
to do it? What is the fluid?

Also, he is also wanting to replace the tubing between the pitot tube and
the instrument. Again, can he do this or does an A&P have to do it?

Thanks...

BTW: After making the mistake once, I would never again "add fluid" to
a compass and replace the seals. After buying a total of 4 kits and
paying almost 5 hours in labor my compass no longer leaks again. For
about 1/2 that price I could have just bought a new compass. It seems
as though the body of the compass warps over the years and getting a
solid seal becomes very, very difficult.

-Robert

My understanding is that your cousin cannot legally work on his certified
airplane's compass, nor can an AI or A&P. My understanding is that an FAA
approved instrument repair station is needed.

At least this is what a buddy of mine (an AI) told me one day when he was
standing over his workbench repairing a compass from another guy's *boat*.
;-)

Aircraft Spruce sells both the correct fluid for a compass and the seals for
the compass. To top off the fluid, you can simply pull the little plug (or
is it a screw ? - can't remember) at the top of the compass and use a
syringe or pipette to add fluid. I had to do that to my *boat's* compass a
few years ago. Apparently compasses are vented and the fluid can evaporate
over time.

KB


"C. Massey" wrote in message
et...
Cousin has a glider and said that he needs to add fluid in compass.

Is this something that can be done? If so, can he do it or does an A&P
have to do it? What is the fluid?

Also, he is also wanting to replace the tubing between the pitot tube and
the instrument. Again, can he do this or does an A&P have to do it?


Thanks...