Leaking quick drains

[wadeg]

Anyone had trouble with leaking quick drains?

I have had dripping occasionally from my wing's quick drains for a while. I went out to fly today (clear/warm/absolutely calm wind) and when i checked my fuel, one of the quick drains would not re-seal. I manipulated it thinking it wasnt seating or had a fleck of fiberglass causing it to drip. No luck. I drained the tanks and took out the quick drains. Both of them had a problem. The o-rings at the top of them were "worn" completely flush with the small indentation in the shaft used to seat the rings. The rubber o-ring should be 'fat' and sticking out from the indentations like a donut in order to seal. Essentially the 'donut' was 'chewed' around it's edge disallowing the seal to occur.

I run ethanol free premium from an oil company here that is reputable. I was wondering if anyone else has had this problem with ethanol free auto gas. Could this be related to some other additive to auto fuel?

[DesertFox4]

yes,

I had several bouts with leaking tank drains on my first Kitfox . I ran 100 LL Av-gas and they leaked. Replaced the seals with Viton o-rings ( if my memory serves me).
I replaced them every year at conditional inspection there after. Always make sure the drains don't leak after you've taken fuel samples. I don't think you'd be able to see a slow leak in flight in the slip stream. On a long flight you may come up a bit short on fuel if you did't catch it on the ground.

I also kept a couple spare o-rings in my tool box on board just in case along with an extra drain fitting.

[Skybolt]

When I first fired up and started flying the Kitfox, I was plagued with leaking quick drains. What I found was little slivers of crap! tiny pieces of glass fiber/resin and the odd building debris. You never know what enters the tanks during the years of building (even though I tried to keep them lidded).

After some time this problem went away and I started to have the squished ring syndrome....I put that down to alcohol blends.

I now use 100LL = no problem.

Of course, If I started out using 100LL, I still would have had the slivers of crap.
Any new flying foxes! keep an eye open and check the fuel filter often for debris coming out of the tanks.

Eric.

[wadeg]

Tested my fuel source and no ethanol.

Another theory I have is exposure during construction to MEK vapors. I developed that theory after my gas cap gaskets lost any elasticity and become hard/dry. Both the rings and the quick drains were in the hangar exposed to MEK fumes during painting. Anyone got an opinion on this theory?

[Skybolt]

Hi Wadeg.

The trouble I have with this theory;
I purchased new quick drain rings from Aircraft Spruce. They come one to a brown plastic lined envelope. And like I said, I changed them on many occasion.

Could MEK and other paint solvents degrade these rings? Probably so and you would have to have the air saturated, more that we could handle breathing the air.

I do know the super unleaded I was using contained ethanol. It said it on the pump.

Eric.

[Mark]

For those builders who have yet to install their tanks:
When I built my first kit, my wife and I spent a good part of a day washing out our fiberglass tanks. We filled them with soapy water and sloshed and sloshed until we could not find any fiberglass slivers or other building materials. (It took two or three rinses to get it all out!) After air drying, we taped all the ports. (Making sure to put some small breathing holes in the taped filller cap port - it tends to rust pretty quickly if air is trapped in the tank.)

I haven't had any leaks in the drain fittings as yet (150hrs) and don't find any debris in the drained fuel. I run mostly 100LL. However I do have one fitting that tends to vibrate itself loose over a period of time that leaks out the threads. I think the thread in this tank may be sloppier than the other.

Anyway, there are "slivers of crap! tiny pieces of glass fiber/resin and the odd building debris" when the tanks are made that needs to be cleaned out before installation.

[kitfox812]

I have been plagued with leaking quick drains also. I put in a new one last week and it didn't drip but it was wet with gas all the time. I pulled it out and found some stringy stuff like you said. Probably from the tank. All non-ethanol fuel used on my tanks. I went to vitron o-rings and put a new one in. It is fine now. I keep a good spare so I can do a "quick change", without draining the tanks. I only loose about 1/4th cup of fuel while I put the new one in. Sometimes down my sleeve if I'm not careful.

Rich L
KF-7
Bonners Ferry,ID