Re: REFLECTOR: Fuel tank venting

[Carl Hoffman <hoffman3@erols.com>]

Of course it's strange. The NTSB and Boeing have been working on the
uncommanded rudder excursion since 1991, and they are hoping to report
soon on the Pittsburgh crash. Maybe we wait for a 3rd one with black
boxes which measure more parameters? 

Carl Hoffman SRGE N1QR


James F. Agnew wrote:
> 
> 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
> 
> --
> //------10--------20--------30--------40--------50--------60--------70--------80
> // James F. Agnew
> // Tampa, FL
> // Velocity 173 FG Elite ( http://www.VelocityAircraft.com/ ) under construction