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Fuel Tank Drain

Stroh21

Well Known Member
Hello VAF!

Easy question (hopefully). I need to replace the fuel tank drain because it won?t quit dripping. Any ideas on which one I need to buy off Aircraft Spruce?

Thank you for your time!

Matt
 
CAV-110

If you want a 1 for 1 swap then it is a CAV-110 and is $16 at Vans or Spruce. But other drains exist and will work as long as it fits the 1/8th NPT fitting in the tank.
 
Don?t forget to get a dozen or so drain valve O rings from Van?s (CAV-110 O-Ring). After you replace the drain valve you can fix the old one so it is ready for the next time the O ring needs replacing.

Carl
 
Hello VAF!

Easy question (hopefully). I need to replace the fuel tank drain because it won’t quit dripping. Any ideas on which one I need to buy off Aircraft Spruce?

Thank you for your time!

Matt

You just need to replace the o-ring in the valve, an easy two-minute job. Here it is at Aircraft Spruce:

https://www.aircraftspruce.com/catalog/appages/oring010.php?clickkey=92808

Order M83248/1-006

Or....go ahead and order a spare valve and rebuild the old one with a new o-ring. Now you have a spare when a valve lets go when you are away from home.
 
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Or:
Get a 1/8" NPT pipe plug. Quickly remove the drain & install the plug. You might get a little gas on your hands, so if you are 100LL adverse, wear nitrile gloves.
Take the leaky drain valve to a hardware, auto parts or fitting supply store in your area and buy a hand-full of the O rings that fit.
Go back out to your plane and reinstall the drain. Keep the plug and O rings in a little Ziploc bag in your flight bag.
BUNA-N O rings are not expensive (IIRC 1/4" OD 1/8" ID)
A link describing BUNA-N and Viton, for educational purposes:
https://www.differencebetween.com/difference-between-buna-n-and-vs-viton/
 
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BTW, when mine started dripping, I replaced it with the spare I keep in my Go-Bag, without draining the tank.

I put my drip tray under the wing. Got the replacement ready, removed the old one, and quickly screwed in the new one with minimal fuel loss.

As the others said, you can replace the o-ring on the leaky one, put it in a zip-loc bag and take it with you. (I also bring a spare fuel cap with me.)
 
You may also just find a piece of debris lodged in there. I had to pull mine a few times when the plane was new.

Larry
 
You may also just find a piece of debris lodged in there. I had to pull mine a few times when the plane was new.

Larry

Does this get better with time? I must have pulled and cleaned each drain 3 or 4 times! Always some tiny piece of debris, 40 hours or so on the airplane.
 
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Debris

Its not a bad idea to drain about a gallon of fuel out of the sump when you take the valve out. That volume and the higher flow rate may evacuate any debris that may be in there. Most tanks I’ve opened up have a little water or trash around the quick drain. That little squirt when we check sumps wont move particles any distance from the drain valve. On the planes I maintain the drain valves come out every other annual/CI for this reason and I usually see some crud. Clean fuel goes back in the tank.

Be Careful. I do this out on the ramp with the plane and drain container grounded.

Don Broussard
RV9 Rebuild in Progress
57 Pacer
 
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Does this get better with time? I must have pulled and cleaned each drain 3 or 4 times! Always some tiny piece of debris, 40 hours or so on the airplane.

Yes. How lng depends on how much debris was left in your tank during the build. I put a valve on mine when i was draining for tank calibration. Have no problema since. As don mentioned, you need to get some real flow to flush out the crud.
 
S/S valve Replacement

SAF-Air makes a Stainless steel version (110SS) Its the very same valve but S/S the other valve is made old steel and CAD plated mine rusted and began to stick open a little. I ordered them direct from SAF-Air
 
`before you spend a lot of time, use an oil can and inject a small amount of engine oil into the valve. fixed a lot of drips on mooneys, comanches, cessnas, pipers and beeches this way.
 
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