Leaking Wing Sump

[Boiler Bill]

My wife and I are looking forward to wing camping this year. It will be our first trip camping. While the plane was in the Hanger, I noticed a fuel drip out of the right wing. The drip came from the valve for testing fuel for water. after a day the spot on the floor was about the size of a 50 cent piece. Maybe on drip every hour. Guess I need to change this. Is it hard to do ? any recomondations ? worried it may effect our camping under the wing.


Bill

[Mike Smith]

Bill,

I replaced both my fuel sump/drains at the last annual. I had a friend standing there to help with the parts handoff (you could have a small table/tall stool to do the same, so parts are close at hand). You need to have the replacement part on hand, take out the current part and quickly stick your finger in the hole, you'll get a bit of gas on your hand/arm, but not too much if you're quick. Get the new part and do the quick "finger off, part in place" maneuver. And that's it!

Prepare ahead of time for a little fuel spill on your hand/arm and the ground. But if you're quick, it will be minimal, maybe as much as 1/4 to 1/2 cup. The key is being quick with the finger/part exchange.

You should consider doing both if you are doing one. It's likely they were both installed at the same time and the other one will have issues very soon if you don't replace it too.

Good Luck,
Mike

[Bruce Fenstermacher]

Bill

Mike is right this can be painless with the right preparation but I'm afraid Mike's explanation might not lead you to think of all that can go wrong and in a quick second have a mess on you hands with a large fuel spill.

What I do is get a 5 gal bucket and place it under the drain. Ideally I have less that 5 gallons of fuel in the tank. That way if anything goes wrong you have something to catch at least 5 gals of fuel while you recover.

Second since it is nearly impossible for any part of you to be above the drain that means that your entire body might be subject to being saturated with fuel. Prepare for the worst. Use eye protection, remove any excess clothing. I usually wear just a T-shirt and pants of course. Have something available to wash the fuel of your body should you get drenched. Fuel burns you will want to get it off ASAP. Have another set of clothes to change into.

Now with these preparations nothing will go wrong and it will be just like Mike described but I do one thing more. As mentioned I'm only wearing a T-shirt when I do this leaving my bare arm for the fuel to spill on to. Since your arm will be above your head any fuel will then run down your arm into your arm pit and shirt. Dam that gas burns your arm pit.

To prevent this I take a rag and tie it tightly around my wrist to prevent any fuel that is spilled from running down my arm to my arm pit.

Good luck.

And BTW this won't fix itself so take care of it before it gets worse. (and do both sides as Mike suggests or you will be doing the other side next week)

[blueldr]

One drop per hour? You have to be kidding. Did you actually spend an hour waiting for the next drop to fall? I sure as hell wouldn't lose a lot of sleep over this.
Why don't you just wait until the next annual.
Believe me, if you're camping under the wing, you're not going to detect or smell one drop per hour.

Old maintenance bootlegger that I am, I would simply fill the tank with mogas thats well laced with alcohol. This will probanly swell the "O" ring on the sump drain and solve your problem. If that doesn't work, pour in a little MEK. I think that stuff burns too.

[Jr.CubBuilder]

Bill I helped Todd swap one of those out, and then I ended up doing the other side the next year. It's really not a big deal if you take a few precautions. Don't wear anything static producing like fleece, ground the plane, you will be touching it and grounded. Just bust it loose, unscrew it and be ready when you get down to the last couple threads. Pop it out, roll your thumb over the opening, and then reverse when you put the the new sump drain in. Safety glasses are a real good idea, don't ask me how I know that. I had to replace the drain on my gascolator also and I really didn't think it was leaking that bad, but my fuel burn between fill ups dropped approximately 1.5 galls and hour after I replaced it. Those drips add up to a surprising amount during the week while you are at work and not flying.

In lieu of that just run that tank dry and do it. I didn't have the balls to do that in the air so I ran the tank down till long after the needle indicated 0 on the gauge.

[logsdon]

One of my drains also leaks a bit. At the last annual, I planned to replace both of them but found them frozen in the fuel tank. Both my AME and I were hesitant to apply a lot of force, not wishing to break anything, so I decided to live with it. Any suggestions as to how to free up a stuck drain?

[blueldr]

With the tank completely empty, warm the area and work the sump drain valve back and forth using a SIX SiDED socket wrench on a hinge handle. I strongly recommend against a twelve point socket because of the limited grip area on the valve which may be made of relatively soft brass. The use of a hinge handle precludes the constant reversing of a ratchet. I have usually found that stuck sump valves are caused by rusted tip threads on steel bobied valves.

[GAHorn]

Let me add a few safety-precautions to this discussion. Move the airplane to a well ventilated area. (Outside the hangar would be nice, away from other airplanes.)
Have a fire extinguisher and a knowlegeable helper nearby who is also equipped with a wool or cotton blanket/quilt. (Tell him to be prepared to smother the flames out when you become a human torch due to static electricity.)
Better yet.... DRAIN THE TANKS FIRST! (This can be done thru the gascolator into gas cans. Ground the aircraft electrically. Keep fire extingishers handy and do this outside....NOT in the hangar where fumes, electricity, other planes and the hangar are endangered.

If your sump is stuck and will not unscrew... it likely is rusted in place due to years of water sitting in that area. Since the tank is drained, soak it in penetrating oil, both internally and externally for a day before using a well-fitting box-end wrench or socket to unscrew it.

Replace it with a completely new drain and sealing ring.

[blueldr]

I had a job a few years ago where the owner had used excessive force removing the sump drain valve and had stripped the machine threads out of the aluminum sump valve boss in the bottom of the tank. I managed to very carefully rethread the boss with a 1/4" pipe thread and used a new drain valve with compatible threads. The pipe threads had to be recut deeper a couple of times to allow the valve to be screwed in deep enough for the cockpit door to clear it when opening. Even then, i wound up with having to put a notch about 1/16" deep in the top of the door for adequate clearance.

[GAHorn]

Thread inserts (Heli-coils) are also viable repair schemes, but the sealing ring may need replacing with a common O-ring.

[cessna170bdriver]

Dick,

I'm sure you had a good reason for making that repair with a pipe thread, but just so we don't confuse those who haven't looked at it closely, the standard installation is a straight 7/16-20 thread. The sealing is taken care of with an o-ring between the bottom face of the tank fitting and the valve. The o-ring comes with the Saf-Air CAV-170 valve. Use of this valve should ensure clearance with the door.

Miles

[Chris Christensen]

I also changed out my sump valves once, for a fairly stiff price.

Examined both and found two conditions:
1- Old shriveled up little itty-bitty O-ring that did not seat well.
2- Small / fine particles UNDER the O-ring which kept it from seating.

Now, I was obviously able to find replacement drain valves, but not JUST the O-ring.
My solutions was to research O-rings for the best fuel friendly versions I could come up with.
Bought a bag of 10 or 20 for a couple bucks.
Replaced the O-rings on my two older drains.

Now I do not have to spend money on new drains.
I was having to change them out every month or so for a while
after have installed the modified Long Range Tanks.

Seems that the problem is over with as of late.
YES, we did everything we could think of to clear any debris out of the tanks before re-installing them. They got a good air-hosing, water-hosing, etc., but still kept getting finite little particles under the O-rings for several months.

PS: it is the same O-ring that is used on the gascolator valve, at least is is on mine.

[cessna170bdriver]

I too replace the o-rings if that is all that is needed. That works until the seating surface pits from sitting in water. $12 is cheap insurance to keep one valve on hand if you find out one day that new o-rings (there are two per valve) don't quite solve the problem.

Also, if you keep a servicable valve with good o-rings around, you don't have to drain the tank just to change the o-rings.

Miles

[GAHorn]

Genuine SafAir fuel drain O-rings are available from Spruce.(877) 477-7823 Cheap.
The tip seal is: MS29513-006, .16 cents.
The base seal is: MS29513-012, .23 cents.
The entire unit is the CAV-170 model, 7/16-20 threads, $12.
http://www.aircraftspruce.com/catalog/a ... safair.php

[Boiler Bill]

I want to thank all of you guys for helping me with changing out the wing sump valves. I will change both sides like you said, and keep a spare on hand. So I took notes and seems to go like this.

1) Push the plane out side away from the hanger
2) set up a stool with all the right tools and parts on it.
3) have a five gallon bucket on hand and rags to tie around my arm
4) Goggles, I have a old dive mask, that should work
5) a Buddy with a fire extinguisher
6) Have a tarp or blanket on hand
7) may as well not take a chance on static, get naked
tie a rope to one foot and the other end to the plane
(this is my own idea so I don't out run the guy with the fire extinguisher)

Piece of cake, You guys are the greatest
Boiler Bill