Re: REFLECTOR: Fuel tank venting

["James F. Agnew" <Jim_Agnew@ibm.net>]

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 blockage
> > >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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