compass refill help !

J

jd winchester

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jd winchester
I have an Airpath compass in my 73 cherokee..... after 37 yrs it has lost fluid.......... I thought the correct fluid was Mineral oil, it smells like mineral oil..... but what I put in was to heavy and response it too slow...

What was I suppose to have used???


(I have a vertical that works great with very little variation)
 
You can buy a complete rebuild kit with fluid and seals from Wag-Aero.
 
I thought Wild Turkey worked best, but I leave it to our avionics & instruments guy, just because that pesky Part 43 leaves out of the PM list.

I could be wrong.
 
Kerosene, Naptha, Lamp Oil, Compass Fluid...anything like that, close to the viscosity of water. You can also use high proof alcohol which is what they used to use until the sailors started drinking it because the US Navy had dry ships. That's why they're also known a s "Whiskey Compasses".
 
BTW, don't log this if you did it yourself. It takes an instrument repair shop to do this legally. And they all know and have the right fluid to use...
 
Steve Foley said:
Don't log what?:cornut:
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The compass fairy never makes log entries.

However, the OP's experience is a good example of why it's important to make sure you know what you're doing before attempting maintenance on your own airplane. I cannot even begin to list all the genuine mechanics who've helped me through that stuff, and to whom I owe a great debt of gratitude.
 
EAA had a good article about how to refill the Whisky Compass. One day, the compass fairy showed up and fixed the one on a plane I once knew.

Aircraft spruce has the parts and fluid.
 
The fluid you get when you buy Compass fluid, is clear lamp oil. at your nearest hardware store.
 
Word is that if the seals in the compass are still good, you can pull the plug out of the top of the compass and refill it using a syringe.
 
If it is that old and losing fluid it is time for a reseal, not a refill.
Try to stick to the correct fluid, I had one that someone figured on an alternative fluid and it turned out to be a great solvent for the glue that holds the compass card onto the float. (the compass card is the conical strip of thin plastic with NSEW etc printed on it, stuck to the part which rides the pivot) So the card had slipped off and was not exactly functional anymore.
A "pal of mine" has found that if you have enough fluid, (after installing new seals) immersing the entire compass in the fluid, then moving it about to remove every last tiny bubble, then screwing the cap on the top whilst still immersed - is the best way to get all the air out. Do the pv=nrt for me, but it seems like a 140F cabin will eventually make the tiniest bubble increase the pressure beyond the limits of the expansion bellows. But I know nothing of this personally, as I am not an instrument crs.
 
Do the pv=nrt for me, but it seems like a 140F cabin will eventually make the tiniest bubble increase the pressure beyond the limits of the expansion bellows.
Click to expand...

If the volume doubles due to the temp, it will still be a tiny bubble.
 
Steve Foley said:
If the volume doubles due to the temp, it will still be a tiny bubble.
Click to expand...

Ah yes but I was asking about the effects on the expansion chamber.
Try leaving a bubble in there, compare the longevity of that compass to one with no air.
 
Thanks guys ! !
I think I found out where the fluid went, when my wife came to bed. Her breath smelled like mineral oil :cheerswine:
 
My compass has the same issue. It doesn't appear to be leaking, but the level is low. I just cant figure out how it comes apart to access the fill port. If I look upwards through the glass I can see the bottom of the plug, but the outside is just a smooth rounded bulb covering the whole back of the compass. I cant figure out how it comes off, as there are no visible fasteners.
 
I can see the fill port through the glass, just cant figure out how to remove the big bulb covering the entire back of the Compass in order to access it.
 
jd winchester said:
.... I thought the correct fluid was Mineral oil, it smells like mineral oil..... but what I put in was to heavy and response it too slow...

What was I suppose to have used???
Click to expand...

You were close but it's mineral spirits, not oil.
 
Mine needed a refill about 10 years ago. What I did...oops...what was done was as Dave describes. The entire compass was submersed in the fluid, rocked back and forth to get bubbles out, then the plug re-inserted before removing the compass from the fluid.

I bought a reseal kit and a quart of fluid and have had just under a quart of fluid sitting in my hangar ever since. It doesn't take much.
 
If you don't know how to do it, I suggest you don't try. The compass refill kits from Aircraft Spruce and other suppliers contain instructions for the process (as well as the necessary fluid and the new seals which are a really good idea if your compass needs refilling), but if you can't figure out how to remove your compass and open it up, you should get someone who does know how to supervise your work.

BTW, even though the compass fairy has been known to visit many hangars when the FAA isn't looking, it's not legal for anyone other than an instrument repair shop to do this. So if the compass fairy does visit, don't create any documentation of that visit in your aircraft maintenance records for the FAA to find and use against whoever signed the entry.

That said, I just noticed you have a vertical card compass like this:

PAI700_cardcompass.jpg


...not a classic Airpath wet compass like this:

airpath-compass-panel-mount-lit-302658--677-p.jpg


That's a lot harder to work on, and I suggest you don't try doing it yourself unless you really know what you're doing. The mechanical portion of that vertical card compass is extremely delicate and thus easy to damage. I suggest that rather than trying to refill it yourself, you take it to an instrument repair shop with the tools and expertise to disassemble, refill, and restore it to proper working condition.
 
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Ron Levy said:
If you don't know how to do it, I suggest you don't try.

Agreed

BTW, even though the compass fairy has been known to visit many hangars when the FAA isn't looking, it's not legal for anyone other than an instrument repair shop to do this.
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When any appliance has a service port, are you servicing it or repairing it. ?

This has been debated at every IA seminar I've attended.
 
Tom-D said:
When any appliance has a service port, are you servicing it or repairing it. ?

This has been debated at every IA seminar I've attended.
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I believe it is service. We were a CRS, but not an instrument shop, and topping off and even changing the gasket on a compass as well as swinging them during an annual was a routine thing I would do.
 
Henning said:
I believe it is service. We were a CRS, but not an instrument shop, and topping off and even changing the gasket on a compass as well as swinging them during an annual was a routine thing I would do.
Click to expand...

changing a gasket, is a repair. Swinging them is a requires a return service also.
 
Tom-D said:
When any appliance has a service port, are you servicing it or repairing it. ?

This has been debated at every IA seminar I've attended.
Click to expand...
Debate it all you want at any seminar you want, but AFS-300 says it takes an instrument repair shop (ask them if you don't believe me). If you want that position overturned, you'll have to get the Chief Counsel to say otherwise.
 
Henning said:
I believe it is service. We were a CRS, but not an instrument shop, and topping off and even changing the gasket on a compass as well as swinging them during an annual was a routine thing I would do.
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Swinging them is within A&P authority. Refilling them is considered repairing them, or so said AFS-300 when I asked some years back. If you need to be sure, ask the FAA.
 
Ron Levy said:
Debate it all you want at any seminar you want, but AFS-300 says it takes an instrument repair shop (ask them if you don't believe me). If you want that position overturned, you'll have to get the Chief Counsel to say otherwise.
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you best ask them again, several FSDO are trying to get that clarified

My bad for leading Ron astray :)
 
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Tom-D said:
you best ask them again, several FSDO are trying to get that changed.
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If some FSDO personnel are trying to get it changed, then they must think the rule is currently what I said it is, or they wouldn't have any need to get it changed.
 
Let'sgoflying! said:
Ah yes but I was asking about the effects on the expansion chamber.
Try leaving a bubble in there, compare the longevity of that compass to one with no air.
Click to expand...

The fluid itself expands and contracts with temperature changes. That's why the compass's convex rear cover uses a rubber diaphragm as a gasket, and the cover has a vent hole in it to let the diaphragm move.
 
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Ron Levy said:
If some FSDO personnel are trying to get it changed, then they must think the rule is currently what I said it is, or they wouldn't have any need to get it changed.
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Not changed, clarified. what is a repair? is this a servicing or a repair?

some believe it is servicing. not a repair. and the FAR say's repair.

The other half of the argument is, if it needs servicing it must be removed.

I'd like to see the compass ferry made legal.
 
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when you add fluid to a compass which did you do?

(a) A certificated mechanic may perform or supervise the maintenance, preventive maintenance or alteration of an aircraft or appliance, or a part thereof, for which he is rated (but excluding major repairs to, and major alterations of, propellers, and any repair to, or alteration of, instruments),
 
Tom-D said:
when you add fluid to a compass which did you do?

(a) A certificated mechanic may perform or supervise the maintenance, preventive maintenance or alteration of an aircraft or appliance, or a part thereof, for which he is rated (but excluding major repairs to, and major alterations of, propellers, and any repair to, or alteration of, instruments),
Click to expand...
You found the relevant regulation -- very good. And it appears you know your FSDO reads it the same way I do. So what's the question? Should it be changed? :dunno: But it's pretty clear you know the FAA's current position is that you as an A&P don't go opening up the magnetic compass.
 
Ron Levy said:
You found the relevant regulation -- very good. And it appears you know your FSDO reads it the same way I do. So what's the question? Should it be changed? :dunno: But it's pretty clear you know the FAA's current position is that you as an A&P don't go opening up the magnetic compass.
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Opening up ? Do you open up a tire to add air? Do you open up your engine to add oil?

Do you consider servicing a maintenance action? a repair or alteration?

That is the issue several FSDOs have requested a clarification. because the wet compasses have a service port.
 
Tom-D said:
Opening up ? Do you open up a tire to add air? Do you open up your engine to add oil?

Do you consider servicing a maintenance action? a repair or alteration?

That is the issue several FSDOs have requested a clarification. because the wet compasses have a service port.
Click to expand...
And when that clarification comes and says what you clearly want it to say, I'll accept that. Until then, clearly the FSDO's do not believe it's a legal A&P action. BTW, simply refilling the compass without installing a new cork seal and rubber diaphragm is like putting air in an old leaky tire, so any good maintenance provider will be making those repairs to the compass regardless of whether merely adding fluid through that port is or is not considered "repair" of the compass.
 
If you look at the design of the wet compass, the plug is not a service port. It should never require service between overhauls as there is no way for fluid to escape or evaporate other than a leak. The plug is just how it's filled following a rebuild.

Of course there is no rocket science involved in rebuilding a wet compass and the only calibration for the unit is a swing which is performed by an A&P anyway because the calibration procedure can only be accomplished after installation in the aircraft, not on a bench in an instrument shop.

Bottom line - the FAA ain't scouring through logbooks looking for compass rebuild entries and even when encountering one aren't going to make a big deal about it. At least I've never heard or read of it ever being an issue.

Buy the kit, do the rebuild, sleep well at night.
 
Silvaire said:
Buy the kit, do the rebuild, sleep well at night.
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How about "Buy the kit, sleep overnight, and then be amazed the next day that the compass fairy has visited"? But don't log the work if you did it yourself unless you did it as an approved technician at an instrument repair station.
 
If it was never broke and still passes inspection, was it ever fixed?
 
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