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Fuel drain valve flange countersinks

riseric

riseric

Well Known Member
Patron
Hi all,

My fuel drain valve flange came with countersunk holes.

The plans calls for size AD 426-3-4 rivets but the countersinks are too big.

PICT4428.jpg


Size 4 rivets seem the perfect size for these countersinks.

I will then drill to 1/8" so the manufacture head sits tighly on the flange.

Anyone else have this issue???
 
Perhaps it mounts on the inside of the skin???

If Vans wanted them to be mounted inside the skin, it would make sense to have slightly oversized countersinks to allow room for the skin dimple. Are you sure it's to be mounted on the outside of the skin...? I was wondering about mine as well, but assumed that mounting inside might prevent water flow out the vent.
 
Drains

They mount on the Outside. Might want to check with Vans on getting new ones ( so they can get the vender to produce the proper counter sink ) . Vans might say put a 4 in it and be done , The Proseal is tuff stuff , but if if have to remove a stuck quick drain, inproper rivets may allow the bung to twist .
If you put 4's in there , disassemble your caged countersink and use it without the cage , woks well in tight spots like that .
Tom
 
i mounted mine on the inside. they look a whole lot better that way.

bob burns
RV-4 N82RB
 
Plans currently show the the drain on the outside for the RV-10 (page 18-2); maybe that's a change...The rivets called out fit nicely on mine, my problem was misreading the length, which became clear after clinching a few. I agree with gzero about checking with Van's, but don't see any reason you couldn't do the substitution you asked about. Just my opinion.

==dave==

RV-10
Finishing tanks
 
As per the plans, they go outside the skin as seen on my photo.

I will contact Van's (don't know why I didn't think about that in the first place...) :eek:

Maybe they sent me the wrong ones...

I also don't see any issue with using a size 4 rivet.

I'll report back with Van's reply.
 
Looks like a NAS1097AD4 rivet would be a good solution for that. Maybe I'm wrong.
 
longranger said:
So the water in the tank has to be about 1/8" deep to flow out?:confused:
Click to expand...

My concern exactly. Looking better doesn't always mean performing better. I'll have to check the parts I got with my kit to see if the countersinks are too deep. If they are, I'll return them for exchange BEFORE prosealing them on. Thanks for the heads up. Good thread.
 
I stand corrected, they do indeed go on the outside. I looked on page 18-3 and in figure 2 it's shown on the inside, but the installation on page 18-2 clearly shows installing it on the outside.
I would not like 1/8" of water traped there.
 
I've never had a drop of water in my tanks in the 10 years that its been flying.

the flange is only .063 thick not .125. its thinner than the rib plus the material left under the flow holes in n the ribs, which would catch water in the outer three bays also. I am not about to loose any sleep over putting them inside.

bob burns
 
Here's another picture on my other undrilled flange.

PICT4441.jpg


On the left is a size 3, and on the right is a size 4.

I measured the diameter of the countersink and it corresponds to the diameter of the size 4 head.

This photo was just sent today to Van's for advice.
 
OK to drill to size 4

If anyone else receives the same fuel drain valve flanges as I did, Van's assistance to builders says it's OK to drill for size 4 rivets.

Build on !!!
 
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