RE: REFLECTOR: Fuel tank venting

[Duane Swing <velocity@metrolink.net>]

Fuel Venting Problem
  I totally agree with Jim Agnew on this one.  Since it was not a 
persistent problem, I would suggest a fuel cap not seating properly and 
allowing a slight vacuum on one side stopping any fuel flow from that side. 
 The single common vent system on the Elite almost always points to a fuel 
cap if uneven fuel flow is observed.  I have personally seen a 1/2 full 
tank actually increase to 3/4 while the other one depleted far faster than 
the engine could use it.  The best thing to do is always monitor your fuel 
system and land before fuel starvation ruins your day.  If the problem does 
not go away, start checking fuel cap seals first.
   Sincerely,  Duane Swing

-----Original Message-----
From:	James F. Agnew [SMTP:Jim_Agnew@ibm.net]
Sent:	Tuesday, March 02, 1999 6:09 PM
To:	reflector@awpi.com; Carl Hoffman
Subject:	Re: REFLECTOR: Fuel tank venting

This all sounds a little strange assuming that both tanks are connected to 
a
common vent.  You will always get some fuel in your vent lines when you 
bank and
the fuel is higher than the vent line.  When you level out the fuel 
draining from
the tank will create a partial vacuum that will suck the fuel/air into the 
tank.
Since the tank with more fuel (deeper) will have more output fuel pressure 
it
will always try to seek an even level with the other tank assuming a slight
positive or neutral vent pressure evenly applied to both tanks.  A water 
level
would not work if this was not true.  Therefore, I would be suspicious of 
the
vent system possibly having some restriction on one leg or a leaking fuel 
cap
allowing a slight vacuum in one tank.

Jim

Carl Hoffman wrote:

> Peter Beaty wrote:
> >
> > O-kay...
> >
> > What's the fix?
> >
> > At 05:37 PM 3/1/99 -0800, Scott Baker wrote:
> >   We believe that fuel must have entered the vent line
> > >during the (initial) fueling of the aircraft and that the common
> > >vent/pressurization was not strong enough to overcome the initial b  
lockage
> > >to this one tank.  Just wanted to share.
> > >
>
> If there is a fix, how do you know it is a fix. Last week a "fixed" 737
> had a uncommanded rudder excursion. The pilots are now trained to cope
> with them. i.e. periodically check the level in both tanks.
>
> Carl Hoffman

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