I'm trying to think this one through, whether it's just a nuisance, or I have to pull and fix my petulant cranky left fuel tank again before final inspection.
Currently, my hangar is 70-ish inside. Both left and right tanks have approximately 11 gallons in them, definitely nowhere near the top where fuel would readily enter the vent line. But my left tank is already dripping fuel out my vent. I'm almost certain this is fuel leaking through from the vent line bulkhead fitting inside the tank, probably the vent line fitting Just Loose Enough [tm].
Question 1 - is there enough normal outgassing pressure from fuel in the tank to push fuel in the vent line up the J-U loops of our vent lines inside the fuselage, clearly above the level of the tanks, until the fuel in the line vents overboard?
Now, the more important question... When I raise the tab on the fuel filler cap, and thus unseal it without removing the cap, I get a large hiss. I'm almost certain this is excess outgassing being released from the tank that didn't make it through the vent line in the fuselage, since the vent line was full of fuel.
This pressurization built up over 2 days, on the ground in my hangar. I'm wondering whether I should be concerned with it in a flight scenario? I'm thinking not, because when fuel is being used up from the tank, now we're dealing with a vacuum situation in the tank, and the vent line is used to pull in air into the tank. It's just going to happen to pull that "leaked" fuel back into the tank.
The real concern I have is whether the vacuum in the tank, in normal flight, will become too much for the tank because the vent line is filled with fuel, and maybe compromise the tank? I'm thinking not, but I'm just posing the scenario. Too many memories of reading too many posts here relating to balloon leak tests and pulling vacuums to pull in Locktite to seal weeping rivets, and posts saying that too much pressurization or vacuum will rupture the tank.
Currently, my hangar is 70-ish inside. Both left and right tanks have approximately 11 gallons in them, definitely nowhere near the top where fuel would readily enter the vent line. But my left tank is already dripping fuel out my vent. I'm almost certain this is fuel leaking through from the vent line bulkhead fitting inside the tank, probably the vent line fitting Just Loose Enough [tm].
Question 1 - is there enough normal outgassing pressure from fuel in the tank to push fuel in the vent line up the J-U loops of our vent lines inside the fuselage, clearly above the level of the tanks, until the fuel in the line vents overboard?
Now, the more important question... When I raise the tab on the fuel filler cap, and thus unseal it without removing the cap, I get a large hiss. I'm almost certain this is excess outgassing being released from the tank that didn't make it through the vent line in the fuselage, since the vent line was full of fuel.
This pressurization built up over 2 days, on the ground in my hangar. I'm wondering whether I should be concerned with it in a flight scenario? I'm thinking not, because when fuel is being used up from the tank, now we're dealing with a vacuum situation in the tank, and the vent line is used to pull in air into the tank. It's just going to happen to pull that "leaked" fuel back into the tank.
The real concern I have is whether the vacuum in the tank, in normal flight, will become too much for the tank because the vent line is filled with fuel, and maybe compromise the tank? I'm thinking not, but I'm just posing the scenario. Too many memories of reading too many posts here relating to balloon leak tests and pulling vacuums to pull in Locktite to seal weeping rivets, and posts saying that too much pressurization or vacuum will rupture the tank.