Fuel Tank Leaks

[Flygirl1]

Looking for advice on how to fix a leak in our quick build kit fuel tanks. We put 4 gal's of fuel in each tank and two out of four of them have evidence of leaks at the baffle weld. These are very small leaks, more like seeps. I'm thinking not worth the effort of taking them out and welding. Hoping someone has an idea on what I can put on the exterior. I would probably put "whatever" on every single one on the bottom just in case new ones appear in the future. D-n-D N241BP/N240BP

[patrickh99]

Proseal is the only thing I know of that would work.

Patrick

[bergy]

I am sure that the zinc-based aluminum brazing rod would work well too. I've done quite a bit of playing and destructive testing with it lately. Melts ~ 700F. Propane torch is more than enough heat. Bought my braze rod at Harbor Freight. And as I mentioned in an earlier post ... if you don't like the looks of it, just wipe it off with a dry cotton rag (I learned the hard way that polyester makes a mess)


I guess I don't have to remind you to clean/vent the tank wellfirst. Maybe put a chunk of dry-ice in it for an hour before bringing the torch around.

[Mark Goldberg]

Donna - if your tanks are leaking it would be the very first time ever that fuel tanks made at our factory have had leaks. Lots of tanks made and never once, until now, a report of one leaking. You think it is leaking from one of the rivets that was welded over? Proseal is good stuff but messy. The aluminum surface has to be very clean for it to stick and work. Mark

[bergy]

http://www.vansaircraft.com/pdf/catalog.pdf

See bottom of page 57

[Battson]

Seeing as you've reported two tanks leaking, whereas many hundreds of earlier tanks from the same production line haven't leaked - it's good cause to investigate what's going on. It seems incredibly unlikely that it's just bad luck.

It would be great to see a photo of the offending tanks. Are you 100% sure they are leaking? Sometime the fuel gets mixed with some pen markings on the tanks, and it looks just like a slow leak (like dried fuel dye).

Alternatively, is there any chance whatsoever the tanks could have been squashed - perhaps stuff stacked on top of them? Or otherwise dropped or impacted in any way? That kind of trauma could lead to small cracks forming in the tanks, and the welds are the first thing which would crack.

[whee]

Just my opinion, now is the time to remove them and make a permanent repair. As frustrating as it may be I would pull the tanks and have them welded if they are indeed leaking. Anything less than that and it would be something that was always on my mind.

[Flygirl1]

I'm absolutely sure these are leaks and I can say I'm also sure the tanks haven't been compromised. Also let me re-peat these leaks are SMALL, very small. One had left enough fuel on the tank to realize I had a leak, which led me to closely inspect every other one. We have a total of two leaks at two welds at the baffle rivet on two tanks. I would say only one of those might be worth welding, (probably not) and if I did nothing to the others, I could accept that as they are so small. I imagine most people wouldn't even know they are there. I would post a photo but my camera isn't good enough to show it. I thought if I could "smear" something on all the welds, that would be good enough and I wouldn't worry about it. If I ever over flow on filling and fuel found it's way into the wing, that would be WAY more fuel than what I am seeing here. I just don't know what would work best. Sounds like pro seal might do the job with the proper prepping. While on the subject what are people using to seal the hole around the filler? Thanks for your thoughts and opinions! D-n-D

[BTAZ]

I haven't done it but I remember seeing something with regards to sealing leaking rivets on Van's RV tanks which might be similar.

Basically involved applying a slight vacuum to the tank and using thinned ProSeal or some particular Loctite product applied to the offending rivet.

Would be worth a web search.

[tailwind]

Empty tank, clean surface with stainless brush and lacquer thinner, wipe dry, apply a coat of jb weld liquid metal, allow time to set up. Your finished.

[Zzz]

Rather than fight them for years, pull em and make a real fix with a TIG torch. Why use JB Weld or Proseal or anything like that? That's for guys with wet wings.

As for just living with a tiny leak, don't do it. My friend has a leak he's chased for years in the wing of his Maule and it's quite annoying to always be smelling fuel when you're not moving.

[Zzz]

http://www.vansaircraft.com/pdf/catalog.pdf

See bottom of page 57

I know it's all pretty much the same, but do note that catalog is 15 years old.

[Battson]

While on the subject what are people using to seal the hole around the filler?

I glued some neoprene rings onto the inside of the wing skin, which seal snugly around the filler neck.

[Flygirl1]

Well I found two more teeny tiny leaks in one tank this morning. (One of the guys says having a "teeny tiny" fuel leak is like being a "little bit" pregnant. LOL ) So as far as welding, which ones do you weld. If I put another 15 gal. in will the weight cause more over time? Who knows, so I still think pro-seal is the way to go. Fortunatly these wings have really good inspection panels to keep an eye on things!! Mark G. thanks for your thoughts and your offer to help. Really appreciate that. If pro-seal doesn't work, I'll give a shout. Donna

[Rollie]

Autozone, etc, sell a two part epoxy type thing that is specifically made for fuel tank repair. I've used it on several things and it seems to hold up well. Its a two part putty type that you kneed together until its a solid color and then put it in place. It sticks really well, can even be applied to a wet, actively leaking tank. hardens up similar to jb weld, but its made to be fuel resistant. I would use that stuff and then just for fun, put pro seal over that. If you do go that route, one time when I bought it it came as two strips of putty, one black one white beside each other, and the last time I bough it it came as a single piece, about 6 inches long and round about the diameter of a tootsie roll, with the white putty in the middle and the black surrounding it. You just cut off how much you think you need and go from there. Good luck.