DO NOT use the default FS9 fuel loading menu - you WILL
experience unintended issues if you use it!
Our 747-400 includes an extremely realistic and complete simulation
of the aircraft's complicated fuel system. In order to facillitate easy
preflight use of the system, we've implemented a virtual fueling truck
of sorts that will automatically balance the tanks correctly as well as
set the fuel pump switches and crossovers on the overhead for whatever
fuel load you enter in.
To access this system, open the PMDG/General/Fuel dialog
and either enter a custom fuel value (you can use your mousewheel to
increment or decrement the value faster) or choose one of the
preselected values. Press OK and the fuel will immediately be loaded
into your tanks.