REFLECTOR:Low fuel light

[Chuck Jensen]

You know what?  This whole fuel thing is pretty stupid!  

It seems everyone is flying around with blinking lights, inaccurate
indications and fuel tanks that feed however they have a mind to, don't know
if their sumps are venting or burping.  Yee gads.  This is stupid.  Probably
the single most important element of flight, fuel, and we don't know and
can't tell when it flows, whether it'll flow, if its flowing and what's left
to flow.

If this were my problem, I'd assign it to one of our engineers.  Then the
next day, I'd take him aside and brow-beat the hell out of him for letting
this inane stupidity go on.  Yikes, it is my problem!  

This is probably a novel, even revolutionary idea but how about some
disinterested third party, like Velocity, issuing a white paper on the fuel
system and how it is supposed to be set up and all the tips, tricks and
traps on a good fuel system?  Or, is it that we aren't smart enough to
correctly follow the building instructions, which are, in fact, correct?

I will leave now to say my prayers of penance for this ugly outburst.

Chuck

-----Original Message-----
From: reflector-admin@tvbf.org [mailto:reflector-admin@tvbf.org]On Behalf Of
John Dibble
Sent: Saturday, July 26, 2003 3:19 PM
To: reflector@tvbf.org
Subject: Re: REFLECTOR:Low fuel light


I think the sensor in the sump is more confusing than it is helpful.  I
think a sight glass would be ideal.  Yesterday I took a 6.5 hour trip.
The low fuel light did not come on until five minutes after takeoff.  At
first it just flashed occasionally.  By the time I got to cruise at 8500
it was on all the time, but went off and immediately back on once in a
while, so I figured the fuel level must be stable at the sensor level.
It's always been this way, and prior to the current discussion I didn't
give it much thought, figuring that if there is fuel in both tanks, the
sump has to be full.  But the idea of vacuum on the tank from a leaky
cap makes me wonder.  What about the tank vent which points forward?
Doesn't this tend to pressurize the tank with a ram air effect?  It
seems that any cap leak would have to be larger than the size of the
vent opening in order for a vacuum to occur and I can't imagine such a
big leak unless the cap is completely off.  It seems like the tanks
would have a slight pressure from the vent.
Also, at 40 gallons of fuel remaining, one tank was 5 gallons lower than
the other.  Applying the opposite rudder equalized the tanks and I was
planning on shimming my rudder like Scot mentioned, until the fuel got
down to 16 gallons.  At that point, both tanks were even and remained
that way.  However at about that time I descended to 4500 to get under
some clouds.  Maybe altitude makes a difference.

John


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