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Paul,
Paul wrote:
Hi, Jim....is
it possible there is a restriction in one of the fuel lines? Are there
any bends in the aluminum fuel line that might have kinked during the
bending process?
This problem drove me NUTS for two years. I
tried everything. For example, I checked the vents as best I could,
leveled the airplane (checked the ball to ensure it was centered - it
was), disconnected the fuel line from the engine side of the firewall
and let it drain into a bucket. I turned off one strake at a time
(with manual maintenance valve) and timed how long it took for the
other strake to gravity drain ten gal of fuel into the sump, out of the
sump through the boost pump, through the filter and then through the
firewall into the bucket(s). Then I turned it off and did the same
thing with the left tank. They both drained 10 gal each within 5% of
the same time. Then I reconnected all the plumbing, taped over the
fuel caps so there's no possible way they could leak and went flying.
Right tank drained 20 gal while the left tank maybe 2 or 3. Level
balanced flight on a cross country. All fuel lines, vent lines, etc.
are as identical as I am able to make them. To this day, I've not met anybody
who can explain what happened. I tried everything. Back and
forth on the Velocity list much longer than you've been inquiring after
your vapor lock. NOTHING. I figured out a workaround - I installed
electric shutoff valves in place of the manual maintenance valves
between the strake and the sump. Now, when one tank doesn't transfer,
I turn off the tank that does and let the "reluctant" tank catch up.
The pump sucks it through the system just fine (the head pressure of 6"
of fuel is about 0.16 psi - a problem that would inhibit that flow you
can't even MEASURE. Assymmetric transfer is common as dirt in the
Velocity community (but not nearly as persistent as mine). It was also
a problem a long time with the Vari-EZ.
Lastly, have
you tried blowing backwards into the two fuel lines to see if either
had more restriction than the other? Just looking for possible reasons
for your uneven fuel flow. Even my Cessna 172 and 150 had fairly even
fuel consumption from the two gravity fed tanks.
I understand that Cessnas had a lot of trouble
around this too.
Just searching
for answers. Paul Conner
----- Original Message ----- From: "Jim Sower"
<canarder@frontiernet.net>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Thursday, February 24, 2005 5:57 PM
Subject: [FlyRotary] Re: Vapor Lock
In my Velocity the strakes gravity feed to
the sump. About a foot of 3/8" Al / rubber fuel line on each side,
downhill all the way. I can run one tank plumb dry and have only a
gallon or two gone out of the other. Like when there's a slight leak in
a fuel cap or something.
If they're significantly uneven, you WILL get air if you select "Both"
... Jim S.
Bulent Aliev wrote:
If you're almost home and have "Both" selected, and one
tank runs dry, what do you end up with in the fuel line? I
believe mostly air. Late in the trip (traffic pattern?)
where trouble shooting time is at a premium. Use L or R.
Not B.
I don’t think so: connect two tanks (one full with water and one empty)
to gravity feed Into Y connection. Than suck on the end and try to
breathe. Let me know how it works :)
Buly
Homepage: http://www.flyrotary.com/
Archive: http://lancaironline.net/lists/flyrotary/List.html
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