Fuel stains on port side wing

C

captain Dick

New member
Friends,
My 2005, 100 hr. 7KCAB hangar queen is developing dark stains behind the small breather(?) tube on the port side wing. I think this is some fuel overflow on the outside of the wing but nothing I have tried to clean the area is working. Or is it some leak inside the wing that is coming thru the back of the fabric and paint? Any ideas would be greatly appreciated.
 
If its around and behind the vent.....its the vent.
Even though there is a check valve to prevent massive back flow, there is a small weep hole to allow for expansion. Fill the tank with cold gas that is in an underground tank and it warms up inside your fuel tanks. It has to expand somewhere. Full tanks these days is really only best when you plan to burn off 10 gallons right away. :)

Edit:
Oh, and is it an 8KCAB?
They stopped making 7KCAB in 1977
 
Jerry, Many thanks for the response. I AM losing it like my wife has often said. The plane is a 7GCBC, N3RJ. Any ideas for removal of the stains? Dick
 
Try using avgas to remove the avgas stain. I've had fairly good luck with that method, as long as the stain is relatively fresh.
 
Friends,
Tried both fuel and Nuvite to remove stains. No luck. Jerry, The wings are Black leading edge and red. Not sure of the paint brand used in March-April 2005. Does it make a difference? Is the factory using something different now? My 1961 restored 7EC was painted a similar shade of red and in 15 years of dribbles, spills and overfills never had a stain. It was painted with Randolph dope I believe. Further thoughts anybody? Many thanks
 
Any paint used after 1999 makes a big difference....thank the EPA for that. If it was paintedin March/April 05...when did you get the stains?
Point is, for a while the paint is still curing. Stains put on through early Summer of '05 are likely permanant. After that, you can work your way up the nastiness solvent ladder trying to get it off.

I inquired with our tech guys as to what we use...I'll keep ya posted.



Edit:
1) McGuire's Diamond Cut compound by hand.
2) Use a DA if the elbow grease is not enough
3) Last resort they use 2500 grit wet sanding

3M Finishing polish to get the shine back
 
Hi Jerry Jr...I find that over time that the fuel stains fade out if you don't fill the tanks over 3/4's full,...leaving some room for expansion...I don't do a lot of inverted flying but even with some loops and rolls the stains haven't reappeared....and I'm extremely fanatical about my baby's finish.....

Tom 151pc
 
Got a good point Tom..and many owners are aware of this but not all.

The Fuel in the ground is going to be pretty cool and after being in your tank for a little bit...will need to expand. The Check Valves have a little hole in the piston of the valve to allow this on the ground. In the air the valve is wide open taking ram air. Now that is pressurized air basically...it only flows as fast as you burn fuel. Therefore, it does not do a great job holding back the expanding fuel (although it does to some extent).

So, it sounds like you can never fill up the airplane? Well, you shouldn't unless you are going to burn off that first part of the fuel immediately. (i.e. get in and fly an hour at a decent power setting). Truck fuel is usually warmer and might help things too. 70 gallon 8GCBC are the worst for this, as you can imagine. Thus, I posted a while back to get 'used' to the 70 gallon system to a prospective new owner.

And...inverted flight shouldn't be an issue. the Vent pipe is then above the Tanks and unless you have some acceleration in another direction from a recent manuver, should not flow out.

I focused my responce on the 'its too late, its stained' OP though.
 
You must log in or register to reply here.
Back
Top