Fuel Stains on Wings

[DesertFox4]

Paul, here is the Mercedes "gas cap gaskets" with part number on the bag.


Mercedes Part# 140-471-00-79


user141_pic3209_1336366781.jpg

This photo shows where to fill the small holes with J.B.Weld so the cap does not leak out the rim while flying. Fill all 4 holes where the yellow marker is pointing.

user141_pic3211_1336366781.jpg

[HighWing]

I think there are a couple of issues here. First and as mentioned, replace the gaskets. The ones original with the caps - at least in the two Model IVs I have experience with are simply junk. I would go with the Mercedes replacement - they work.

Then one day on the way back from the Desert Fox fly-in years ago, I unwisely had the line guy fill the tanks. He didn't seat the cap on the right wing properly and my first indication was the fuel in the sight gauge dropping almost as I watched it. We landed in Eli and without mishap. The point - on the top of the wing there definitely is a negative pressure and if the fuel level is even close to the filler neck, it will suck the gas out of the tank. A side slip with a poorly fitting gasket will not only leak but will become a fountain due to the negative pressure on the top of the wing.

Talk in the past regarding removing avgas stains also included using the fuel itself as a solvent with positive results. I have never had to try it, but this from reports.

[Paul Z]

Paul, here is the Mercedes "gas cap gaskets" with part number on the bag.


Mercedes Part# 140-471-00-79


user141_pic3209_1336366781.jpg

This photo shows where to fill the small holes with J.B.Weld so the cap does not leak out the rim while flying. Fill all 4 holes where the yellow marker is pointing.

user141_pic3211_1336366781.jpg

I plan on ordering a set, they are Blue they match my plane. I'm order them now, now that I have my paypal Password figured out. They will ship in 3 days.

$14.95 at Mercedes Benz Online parts, http://www.mbonlineparts.com

[jiott]

Thanks for all the info. I will try the Mercedes gaskets, but I think its coming right out the vent tube when tanks are 3/4 or more. I will also try some of the cleaning methods mentioned.

[jamesmil]

I found that my right tank would leak badly from the cap the first time I topped off the tanks? Made a mess on top of the wing and down the side of the fuselage . I had never topped the tanks off so as to keep it light to land on the beach , had over 100 hr, on it before I need to top it off, after I got back home and inspecting the cap I found the front tab of the cap was bent a down a little and was not sealing the cap at the front. Bent the tab to get a good seal and fixed the leak when full. As for cleaning the stains I use 3m adhesive remover. Comes in a red and white quart can with a small plastics squirt nozzle. Be sure to reapply a coat off wax after using as it will take all the wax off but doesn't cut the paint. We used aero thane paint not sure about other paints so should try a test spot first. Hope this helps

[Paul Z]

I'll have to try the 3M to get my stain out. What type of Wax?

[Av8r3400]

Beware! 3M adhesive remover will take off Poly Tone slick as a whistle. It contains MEK, among other things.

[jamesmil]

thanks for the info on the poly tone av8r3400. as for the wax I really like the products from California custom products especially there metal polish. this is the link to there site. http://www.californiacustom.com/