Saturday October 16th, 2010|
Fuel Tank Leak
Wow, a maintenance-related update!
The airplane has been relatively maintenance-free. I am at about 350 hours on the plane and I've been pleased. Other than trying to find the right autopilot (documented previously on this site) and cracking the FAB mounting plate, I have not really had many issues...until now.
As is often the case I came out a couple of weeks ago to fly the airplane and the first thing I noticed when I walked into the hangar was a *big* blue stain on the floor under the airplane. Ooops.
Today I was finally able to make it out to the airport to pull the tank and see what was going on. Well, here's your problem! I apparently fell prey to the recent problems others have reported regarding 'soft proseal'. I literally could wipe the proseal in this area off of the tank with my finger. It was as though it never set up. I know that others have reported the same problem. In fact, I definitely remember using the "Flame Master" brand in this area. There was another small area on the rear baffle where I could wipe away the sealant. I used some MEK and cleaned up all the 'wet' proseal and re-applied nice new beads of proseal around the troubled areas. The corner that was leaking was the infamous lower aft corner on the inboard edge (presumably one of the most common places for leaking). I was actually able to push some new, good pro-seal back inside the open corner a little and apply a nice big bead around this area. While I was at it, I cleaned up the whole side of the tank that was looking nasty.
The thing about a leak on the inboard edge of the tank is you can't really see where it's leaking from by the blue stains alone. There's enough air flowing through the wing root that it blows any fuel all around and gets blue dye everywhere. It was even blowing to the mid-point of the tank on the rear baffle. That's why I pulled the tank -- to ensure that there was no way the tank was leaking back there. That fix would not have been fun.
There has been quite an active thread on VAF about this. Check it out here.