[Gordon Martin]

I am building an old RV3 kit with the fuselage fuel tank. There is a 90 deg. vent fitting that points down from the top of the tank. Does anyone know where the vent tube is supposed to exit the fuselage? Van's wasn't able to help any with this question.

 

[dlomheim]

Fuselage fuel vent question

I am building an old RV3 kit with the fuselage fuel tank. There is a 90 deg. vent fitting that points down from the top of the tank. Does anyone know where the vent tube is supposed to exit the fuselage? Van's wasn't able to help any with this question.

Gordon:
How did you finally end up running your vent? The RV-3 we are restoring had soft aluminum tubing that ran from the 90 degree fitting on the top front of the tank and then down to an AN bulkhead fitting on the floor boards by the firewall. A piece of aluminum tubing was attached to the underside of the skin and then was simply bent forward sort of like the pitot tube out on the wing. A problem with this installation was that over the 180-200 hrs. that aircraft operated, the top angle aluminum cut into the soft aluminum tubing just below the fitting so I will need to reroute it this time to eliminate that issue.

How did you end up running yours?

Thanks.

Doug Lomheim
RV-3A restoration

 

[Gordon Martin]

fuel vent

I haven't actually done the installation, but I was planning to do it exactly as you described.

What do you think caused the damage to the vent Line? Was there enough movement of the tank in the hanger straps to cause the damage? I am planning to install "bumper brackets" at the fore side of the tank in addition to the ones at the rear to help prevent any forward movement of the tank. Let me know how you solve the problem.
-Gordon

 

[dlomheim]

Fuselage tank venting location...

Mine wasn't built with the sling method at all which has me wondering after reading the plans, etc. if I should re-do it in that configuration. The original builder had his fuel tank welded up with flanges down both sides that all the tank to sit on the longerons. We've all seen how much flex there is in those longerons at start up adn shut down which get transmitted all the way to the horizontal and vertical stabs and can really thrash them pretty good from time to time, and that twisting moment would be transmitted to my tank as well; which is why Van's instituted the "sling" installation method I believe.

Back to the vent line; the reason the vent line got a slit chaffed in it from the aluminum angle piece was simply that the tank was built so far forward that there really wasn't enough room for the vent line to run straight down (from the 90 degree elbow) without rubbing on the angle aluminum piece. The original builder was okay with this (?) and didn't even put a rubber hose or something over it to help with this chaffing issue, so I have to deal with it now.

The most recent article of KITPLANES had an interesting article on fuel vents and if I recall the article correctly it stated that there shouldn't be a low point in a fuel vent line, etc. My initial thought immediately was: "But that is how my 9A was designed...". Anyway, I wonder if there would be any downside to just keeping the "3" vent line up high and running it out the top through the fuel tank cover...maybe a little ugly, but it would be effect I'd think...

Decisions, decisions...

Doug Lomheim
RV-3 Restoration

https://www.dropbox.com/s/gbtqnr1n63wh0vt/Fuel Tank Mounting Flange.jpg

https://www.dropbox.com/s/20j70owc36b8aoy/Vent Clearance Issue.jpg

 

[Gordon Martin]

Fuse fuel tank

It looks like from the pics that your fuel tank is somewhat longer than mine. It doesn't look like you have much clearance at the front. How much room is there between the tank and the panel at the aft end?

I think you might run into logistical problems if you try to run the vent line out the cover over the fuel tank...how would you connect it up? And if any fuel vents out, would it go right onto the canopy? By running the vent line out the bottom you can connect it all together before you put the cover in place.
-Gordon