Hello group,
I had an interesting situation yesterday during climb out. The airplane had
about 15 gallons onboard according to the totalizer. I have the fuel tank
vent going from the tank top to the top of the filler neck, then another line
going from there to the bottom of the fuselage with a 3/8 inch aluminum tube
bent and facing forward, in the same idea as the manual calls for on the top
vents. During the climb, I noticed that fuel was filling up in the filler
neck. It kept rising to the point where I leveled off before it looked like
it would reach the vent line going to the bottom of the fuselage (dumping
fuel overboard at that point, I would think).
There was turbulence and I started to wonder if I have done something, since
I had not seen this before. When I leveled off, the problem went away.
I have concluded that since the tank has a flat top with one vent tube going
to the forward top of that flat surface (on the starboard side), if there is
an air gap with the tank down slightly, and if the airplane is not
coordinated, the air pocket could be trapped over on the port side of the
tank, with fuel on the starboard side. As the airplane climbs, the trapped
air would expand due to the outside air pressure being reduced, and that
would force fuel up the filler neck. I didn't think of slipping or skidding,
as the case may be, when I was climbing to see if I could stop this from
happening. Initially, I thought the fuel was being sucked up the filler neck
by a low pressure in the vent, but after sleeping on it, I think my
explanation is correct. The airplane now has 45 hours on it and I have never
seen it do this -- or noticed it anyway.
Any other with any information would be appreciated.
Thanks,
Dave
A227
Mini U2
|