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1. 10:39 AM - Case closed on "the case of the missing fuel" (MPPalmer@aol.com)
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| Subject: | Case closed on "the case of the missing fuel" |
Hi All:
If I don't take ten minutes to write this now, I'll probably never get around
to it.
A few months ago, I posted on this list server that we were mysteriously
losing fuel in our Glasair. That, after 12 years of the Fuel Totalizer always
being an accurate predictor of how much fuel remained in the tank, something
suddenly changed and we were ending up short of fuel. Once, in flight!
I did two things to the plane that solved the problem. Not a great
experiment, because I don't know which variable changed things. (One, the other,
or
both?)
I blew out the vent lines like I never have before. I disconnected the
"cross" fitting in the middle rear of the wing (where the two wing tip vents connect
in the GII and GIII vent topology). With the tanks 3/4 full (to keep air from
one side of the wing from leaking to the other side), I blew air into each
wing tip, one at a time. That not only blew air out the middle vent, but it also
siphoned fuel along the way. A bit of a mess, but a good purge of any solid
blockage.
Then, when I reconnected the fittings to the cross, I made a longer outboard
vent tube. That's the one that sticks out the belly pan. Our old vent tube had
slowly eroded (exhaust gas?) and was only about a two inch stub. I had
noticed some staining around it, but hard to know if fuel. (We painted the bottom
half of the plane a deep red and it's difficult to see 100LL blue stain on the
red.) Now the vent tube protrudes four inches, as it used to.
One of those two things (or both) solved the problem. It's been a few months
now, but the Totalizer is once again a reliable indicator of how much fuel
remains in the tank.
I'm thinking it was the short vent line that was the culprit. I theorize that
it had eroded to the point we weren't getting positive pressure in it anymore
(it's in the dead air of the cowl scoop) and was actually in a lowish
pressure area, siphoning fuel outboard in flight when the tanks were full.
Thanks for all the suggestions. I'm glad it wasn't a leak in the wing.
Mike Palmer <><<BR><BR><BR>**************<BR>The year's hottest artists on the
red carpet at
the Grammy Awards. AOL Music takes you there.
(http://music.aol.com/grammys?ncid=emlcntusmusi00000002)
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