leaky "saf-air" drain plug

leaky "saf-air" drain plug

When our newly acquired C172F was pulled into our hangar after flying it home I was dissappointed to see a steady drip, drip, drip of oil coming out of the cowling.  We had just flown it home from the seller's field after an annual and a pre-buy inspection from an IA.

   Our CFI shook his head and said "you better get that checked before it goes up again" and our hopes sank.  Being a decent mechanic on most things except planes, I decided to pull off the cowling and check things out.  Everything underthe cowl was just coated with oil and the sump was 2 quarts down. 

   I carefully cleaned all the oil off with degreaser added oil and put the plane on paper.  2 days later, no leaks.  Started the plane and let it build pressure and behold the drain valve nipple was the cause.  I checked online and that little valve cost $69 but the orings were replaceable.

  What really bothered me was their is no backup safety system on these drain valves.  I am a lawn equipment dealer and even our least expensive riding mower has a quick drain valve that has a back up in the form of a snap cap that fits tightly over the nipple in case the valve starts leaking. And our valves are just $7, not $69. 

   I've read much of FAR/AIM in my flight training,am not a fan of big government, and think I read something that allows a pilot to bend a rule to make sure his plane is safe.  Maybe I will get in trouble for this, but my plane is now safer for me and my son because of what I did next.

   I went to the local hardware store an bought 2' of 3/8" clear high pressure sprayer hose (100psi), a 3/8" brass barbed hose nipple, a 3/8" brass cap, and 2 stainless clamps for about $8.  You clamp the hose on the "saf-air" valve's nipple, stick the brass barb in the other end of the hose, clamp it, and cap it off.

Now if this valve leaks, all the oil on't spray out over our engine or worse.  And the oil doesn't get all over the front wheel when draining. I just pull off the cap and stick the hose in a jug.  And I can spot it if the valve leaks again thru the hose.  I tied up the hose with some velcro I had to one of the engine mount struts to keep things tidy.   

  If I find out I'm in trouble or at the next annual, I can pull it off with one clamp.  But I know this is safer than what the fancy valve with the bright colored papers is all by itself. We haven't flown it yet like this, I'll consult an A&P for an opinion first as I don't want to go to jail over an oil valve.

  But there is no uncertainty in my mind that I don't want to fly in a plane with one of these fancy blue $69 valves with the colored tags unless that nipple is capped.  I don't want to crash over a dam oring.

   Hope this helps somebody else.     Joe Cronin

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Re: leaky "saf-air" drain plug

Hi Joe
Your "fix" is considered the use of non approved parts, which is a violation of the FAR's. As an IA, it would leave my shop with this "modification".  The cheapest fix for your problem would be to use a standard Continental plug, P/N 532432 and a crush washer,P/N AN900-10 which can be had for around $10. Oil changes are a little more messy but the plugs do not leak and is more of a piece of mind than a drain valve. I personally do not believe in the oil drain valves because of the reasons that you stated. Not trying to be an ass, just trying to help out....

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Re: leaky "saf-air" drain plug

I seem to remember a case where a plastic hose was attached to the oil drain valve on a Piper. During cold weather operation, turning the nose wheel (taxi) caused the valve to open because of the hose. I don't remember what the cold stiff hose hit that pushed it up. This was a safety item shown at a "WINGS" meeting. Things you think are safe can happen.

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Re: leaky "saf-air" drain plug

Thank you both for your replies.  I did notice that aeroquip makes a drain valve with a hose attached for $155. Lot of money for an added hose, wonder if it's got a plug in the end like mine?

I appreciate your advice and will take my hose off before it goes to an FAA certified mechanic.  Yet as a lifetime mechanic I know its safer with it.  Remember I capped the end, it's rated well over the oil pressure, and this in a fixed gear plane and I secured the tube to the engine mount structure.  So you have 2 mechanisms in place to stop the oil from leaking. And when I drain the oil it's not going all over the nose wheel.

I've actually tried to read much of FAR but I am having a hard time accepting some of it and some of the aviation mechanical practices. For instance why all the sump plugs and strainer plugs are hard wired together while the oil temp sensor that screws into the strainer plug is not? They all leak oil if loose.

My 17 year old son is having a harder time with this.  He's been accepted to a good college aviation technology program, is in pilot training and is a helluva mechanic for 17.  He has worked in the shop of our family lawn and farm equipment shop since he could twist a wrench.  He also built a 2000 camaro ss for the track with tons of performance upgrades, nitrous, and learned enough about engine dynamics to do custom computer tuning.

He asked me why these valves don't have caps or hoses with caps?  Why we never see quick valves leak in our shop when capped?  Why these engines still use points? Carbs? Plain valve materials? Why aviation cleans spark plugs when I have told him on other engines that is a no no because of the possibility of the abrasive getting stuck onto the plug and later releasing into the cylinder?  I could go on and on.
I tell him the standard "because they work" but it doesn't go far. He said if that was true we'd all be driving 1968 cars.

He'll get his education and will be an asset to whatever type of shop he lands in.  He loves to fly and the only thing that will turn him off an aviation career is probably stuff like this. He knows FaR is the work of lawyers and politicians and that doesn't sit well with most kids these days.

Anyway, again thanks for your reply and advice.   Joe

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