REFLECTOR: Odd fuel stain?

[Al Gietzen]

Scott;

In a steep climb and near full fuel the fuel level at the front of the
strakes is above the top of the loop of the vent line at the firewall;
allowing fuel to go out the vent.  Used to happen quite often on my std RG
and 20B rotary.

One solution is to bring that vent line loop forward along the top of the
fuselage.

Al G

-----Original Message-----
From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
Behalf Of Scott Derrick
Sent: Sunday, November 20, 2011 4:19 PM
To: Velocity Aircraft Owners and Builders list
Subject: REFLECTOR: Odd fuel stain?

So after design/install of a new forward cabin heater system I took the 
bird for a test flight.  I as also testing a new oil temperature sensor 
which is working fabulously!

Played around to the north of GNT getting the plane setup for LOP at 
9500 and playing with different settings of the heater controls, there 
is a separate control for pilot and co-pilot positions, plus the oil 
flap provides full or reduced air flow.

The problem occurred when I did a walk around in front of the hanger 
after the flight and saw a bit of a fuel(blue) stain on the rear cowl! 
Thats really odd I thought!  It started about a foot to the rear of the 
fuel vent and was kinda wispy looking, about a foot+ long.

I was pretty upset as I don't like fuel leaks, who does, and we are 
planning on flying to Tahoe Tuesday morning. I was contemplating where 
it could have come from, There is no way it cam from the engine 
compartment, it would have pooled at the low point in the bottom cowl 
and come out the drain holes, and this was nowhere near that. Plus the 
fact, is was directly in line with the fuel vent, but why would it spit 
fuel in flight!

Then I had an idea.

When I came back to the pattern the airport crowd requested a low pass, 
you know an altimeter/compass check, so I sucked the gear back up and 
did a 185 knot 100 ft pass down the runway.  Turning about 2600 RPM, at 
mid field I pulled up into a  steeper than usual climb, about 4,000+ ft 
per minute, the speed rapidly unwinding, the altimeter doing the 
reverse. At the top, about 1,000 agl and now at 120 knots I pushed over 
a little more aggressive than I usually do, going just a bit negative G 
for 5 seconds or so, leveled off and made a sedate pattern to landing.

My fuel tanks are almost full, about 26 gallons in 30 gallons tanks.

Now I wonder did the negative G maneuver cause the fuel to spit out the 
vent?  Anybody else experience a similar thing?

Scott

-- 
We are all here for a spell; get all the good laughs you can.
Will Rogers
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