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Fuel Drain Connection leak

didja

Active Member
So..... apparently, I was an complete idiot and forgot to put proseal on the inside face of the drain valve flange plate before riveting to the skin.... or just a partial idiot and didn't put enough.....

Either way, I am hoping that someone may have an idea of how to seal this up permanently without cutting into the baffle...….

The leak literally comes from every angle of this flange plate, indicating to me that I was a complete idiot and not just a partial one!!!

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I have the kit so that I can cut a hole in the baffle to get to the backside of this if I have to, but if there is something that someone thinks would work without having to do that, that would be awesome!!!
 
It didn't look as if you'd filleted the edges of the flange. That would probably be worth a try.

You might try using the Type A tank sealant (you can get it from www.skygeek.com). This works the same but has a thick syrup consistency instead of a paste. Your choice.

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Dave
RV-3B still building
 
If there is no sealant, the only correct way to correct it is to remove the flange and reinstall with sealant.

I think there are some decent quality 3/32 flush blind rivets that could be used in place of the AN426's, that should be exceptable to use and would allow you to avoid opening up the tank.
 
I had thought about doing the fillet idea around the edges, but that seems too temporary to me, and I think that I would be yanking the tanks off at a later date to fix it correctly.

One idea that had heard from a fellow builder at the hangars was to remove the fuel sender and access the back side through the fuel sender access hole and then re seal the sender and screw back in place.

I think that this will be the way I try to correct it, but if that doesn't work, then I will try the blind rivet method. I will have to contact van's to see if they make the solid blind rivets similar to the ones used in the Z-attach brackets for the tanks......
 
The rivets on the drain flange are countersunk; I know they make them, as we used one to seal a leaking rivet under the wing walk on my QB tanks.

I'll have to see if I can find the Spruce part number...
 
Well, got the flange drilled out and pulled from the skin. There was a *very* thin layer of proseal between the flange and skin. It didnt take much effort at all to peel the flange from the skin.

The unfortunate part is that I cant seem to find a 3 series closed end sealing blind river (3/32 size) anywhere. I can find lots of 4 series (1/8 size) but that is so far as small as I can find.

I have two options, as far as i can tell..... pull the fuel sending unit and get access that way to be able to buck new solid rivets with the existing size, or confer with Van's to see if these would be ok to drill out to the size needed for a 1/8 closed end sealing countersink blind rivet.......
 
The unfortunate part is that I cant seem to find a 3 series closed end sealing blind river (3/32 size) anywhere. I can find lots of 4 series (1/8 size) but that is so far as small as I can find.
I have two options, as far as i can tell..... pull the fuel sending unit and get access that way to be able to buck new solid rivets with the existing size, or confer with Van's to see if these would be ok to drill out to the size needed for a 1/8 closed end sealing countersink blind rivet.......

You don't have to use "closed end" rivets. My biplane tanks are built exclusively with regular pulled rivets. Proseal will weal the stem hole fine.
 
You don't have to use "closed end" rivets. My biplane tanks are built exclusively with regular pulled rivets. Proseal will weal the stem hole fine.

Yea, I actually just got off of the phone with van's tech assist and he stated the exact same thing.....just use the flush blind rivet, use lots of pro seal to hold the flange in place, and use a good amount around each blind rivet..... I think that this is how I am going to do the repair.

My understanding is that the shop ends of the rivets that were drilled out should not be a problem with the strainer being smaller than the drilled off shop heads of the old rivet......
 
Here's another online resource, not sure if the grip length is enough for your application:

https://www.baysupply.com/2472182/Product/Pop-Closed-End-AK42H

Spruce has them too, I don't think the pic represents the actual product:

https://www.aircraftspruce.com/catalog/hapages/blindcloseendomehdrivets3.php?clickkey=266960

These are too big. I would have to drill out the flange holes to 1/8. The van's tech assist rep said that it wouldn't be a big deal to drill these out, but I don't want to risk getting metal shavings into the tank.

I tried to find the 3/32 needed for the existing hole sizes, but just couldn't find any anywhere.......

I will try simply using countersunk blind rivets dipped in lots of proseal, with lots of proseal between the flange and tank skin, and squirting a good amount of pro seal through each hole just to try to cover the rivet as best I can. After all that sets, then try the pressure test again.

Then, and hopefully this wont be the case, if it fails, I can simply open it up through the fuel sending unit and buck in some solid rivets.....
 
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