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Saf-Air Oil Tank Drain Leak

rgmwa

Well Known Member
I’ve had a Saf-Air M12175 quick drain in the oil tank for about seven years and have been happy with it. It started losing a small amount of oil recently so I replaced it last week with a new one. Went flying today and this one also appears to be leaking slightly judging by the oil streaks on the belly. It’s probably lost no more than a quarter cap full of oil, if that, in a 1.5hr flight. The oil appears to be coming from the outlet and not around the crush washer. Anybody else had any experience with these drains?
 
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I’ve had a Saf-Air N12175 quick drain in the oil tank for about seven years and have been happy with it. It started losing a small amount of oil recently so I replaced it last week with a new one. Went flying today and this one also appears to be leaking slightly judging by the oil streaks on the belly. It’s probably lost no more than a quarter cap full of oil, if that, in a 1.5hr flight. The oil appears to be coming from the outlet and not around the crush washer. Anybody else had any experience with these drains?

MOST of these quick drains that leak can be repaired by replacing the O-Ring that is on the center part of the drain or cleaning debris that is preventing the O-Ring from making a good seal.

My suggestion is to take the old one you removed, lock it open like you are draining the oil, then attempt to see if you can get the old O-Ring off. Once off, use it to get the correct size new O-Ring. Once new O-Ring is installed, the drain can be reinstalled.
 
Thanks Gary. Yes I was aware you could get replacement seal kits but decided to get a new valve instead. Being in Australia I could get the valve from ACS but they didn’t list the seal kit. I didn’t expect a new valve to leak but I guess it can happen.
 
Having chased a few oil leaks they often are far from where you think. Having installed a new valve I would be looking in other places unless you have confirmed that is the leak.
 
The cowl directly under the valve is oily and touching a rag to the drain outlet results in oil soaking into it. I’m not entirely discounting other sources and will check again but the drain looks like the source.
 
Do you have a drain hose permanently connected? The weight and stiffness of an added hose will put strain on the o-ring seal...
 
No permanent hose, Jim. The old drain worked fine for seven years. I know the o-rings don’t last forever and that leaks happen but was surprised that the new valve would have a problem.
 
I slipped an appropriately-sized short piece of clear plastic hose over the end of the drain's outlet tube and sealed the end of the plastic hose. In this way I can see if there is any leakage from the drain and it also serves as a secondary (albeit not of airworthy quality) containment valve -- a "belts and suspenders" kind of thing. Also be sure that your drain valve is not touching any portion of the oil tank internals -- there are some valves that fit correctly and some that need an adaptor. Also check for cracks around the drain mounting boss at the base of the oil tank -- it is possible that some past incorrect torquing of the drain plug has created some cracks. Also due to the swirling air currents in the rear of the engine bay, slight normal leakage from the oil breather tube and/or mechanical fuel pump breather can appear to be from the oil tank drain area. All in all, it is probably a bad o-ring.
 
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Thanks David. I’ll try a short piece of tube to make sure it’s the drain. I’ve checked the oil and fuel pump breather tubes and don’t believe it’s them. There’s nothing contacting the drain and it’s the corect type for the Rotax oil tank. Also used a second spanner when torquing but will inspect for cracks. The leak is very small but leaves the same swirl pattern on the belly adjacent to the two bottom cowl screws that the original leak did, only much less. Thanks for the tips.
 
I’ve had a Saf-Air N12175 quick drain in the oil tank for about seven years and have been happy with it. It started losing a small amount of oil recently so I replaced it last week with a new one. Went flying today and this one also appears to be leaking slightly judging by the oil streaks on the belly. It’s probably lost no more than a quarter cap full of oil, if that, in a 1.5hr flight. The oil appears to be coming from the outlet and not around the crush washer. Anybody else had any experience with these drains?

I don't care for Saf-Air. It's a poor design. Amazed they still sell them. The rubber seal inside fails and they leak/drip. Get one that has a ball-type valve(EZ Drain or Fumoto) or perhaps better yet, a ValvoMax.

https://www.valvomax.com/
https://ezoildrainvalve.com/index.html
https://www.fumotousa.com/
 
What is proper way to safety wire a quick drain? Or is it necessary to safety wire? On my RV safety wire may have pulled up slightly on valve and I had just a drop of oil on the outlet.
 

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What is proper way to safety wire a quick drain? Or is it necessary to safety wire? On my RV safety wire may have pulled up slightly on valve and I had just a drop of oil on the outlet.

I can't tell in the picture if the quick drain base is saftied to the oil tank but it should be. It looks like the valve is safetied to itself. The quick drain itself (the arms) are not normally safetied as it is held down/closed by spring pressure. As a side note, the safety looks improper to me in the picture. Wraps are the wrong amount and not safetied in the proper direction to prevent rotation (counterclockwise) of the arms to the up/open position.
 
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The photo isn't very clear but the wire from the hole in the tank fitting to the valve arm is vertical and therefore would be unlikely be as effective as it should be. The valve could potentially loosen enough to leak, although the wire would stop it going very far. The safety wire should pull positively against the direction the fitting would want to rotate if it came undone, but this valve doesn't appear to be drilled for safety wiring anyway. What brand is it?
 
I don’t see any way to safe wire this valve. I will wire body at next oil change to tank fitting, good observation!
 
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