Fuel vent leak

The fuel vent in the right tank began leaking about 6 months after first flight, and it has been steadily getting worse.

The left tank started leaking right away and we had to remove it and return it to Vans, but since then the airplane has been painted and we REALLY don't want to take the tank off. I built that special tool where you could tighten the B nut thru the fuel sender hole, but with all the might I could muster I couldn't budge that nut. It's TIGHT, and I suspect so tight that the flare has been cracked.

I also tried inserting a 3/16" dia by 3" long Delrin tube, liberally gooped up with fuel resistant silicone, up the vent tube in an effort to seal it off, and that exercise failed. I was also concerned that fix would restrict the airflow into the tank during use.

Does anyone know of a fix that wouldn't require wing tank removal? I suspect I already know the answer, but hope springs eternal. And I have to say I'm more than a little annoyed at Vans - we opted for the QB kit (and paid an extra three grand) precisely so we WOULDN'T have these issues.

You already answered your own question. Take the tank off and send it to Van's for repair, or better yet, get the tank baffle repair disc kit and do it yourself. I don't understand why Van's does not insist on better quality control on their QB tanks!

Tank baffle repair disc kit?

tank baffle repair kit

This thread shows the use of the baffle kit available from vans.

http://www.vansairforce.com/community/showthread.php?t=173106

I would consider making a tool/appicator to apply proseal around the internal AN fitting / line (inside the takk) to stop the leak. I suspect that with an inspection mirror and the right shapped applicator, you should be able to seal it up without pulling the tank, by going in through the fuel level sender hole.

I would NOT try to seal it from the inside of the fitting / tube for risk of blocking air flow.

Larry

I had a similar problem on one of my QB tanks on my RV8. I found the B-nut barley finger tight. A buddy at our airport had a leaker also, except his B-nut wasn?t even installed. All together we have had 4 QB tank B-nut leakers and our airport (KHAO). Something worth checking if you get QB wings. I had to remove my right tank and therefore justified buying this tool:

https://www.homedepot.com/p/Milwauk...ERCH=REC-_-pipsem-_-203111680-_-202957709-_-N

I was able to remove the tank in about 45 minutes. Putting it back on was even quicker. If your screws have been painted on, it will probably take you a little longer to cut the paint around the screws, and then to make the left and right match...... no doubt this is your most frustrated concern about your pretty painted airplane and a too common QC miss by the tank builders.