You probably know this JT...
Loading fuel, structural considerations. And here, about the 747 classics.
We deal of course with MZFW in one hand.
Then the location of that fuel in the airplane... CWT and wing tanks.
Yes, there is definitely a sequence for fuel use.
Structural considerations (again) and CG location because of swept wings.
xxx
We load 747s wings first. Main tanks, then reserve tanks nš 1 and 4.
Then it is filling the CWT... some even have an additional FWD AUX tank.
Then we finally fill reserve tanks nš 2 and 3 (near the tip of wings).
xxx
Taxi and takeoff is done main tanks to their respective engines.
As soon as flaps up, reserve tanks nš 2 and 3 are emptied (reduced VMO limits).
Then we empty the CWT to achieve an aft CG (takes hours at times).
Finally, our reserve tanks nš 1 and 4 are emptied at top of descent.
We generally land with say, 3 tonnes remaining in each main tank.
xxx
A structural limit that is not often mentioned by pilots is WBW wing bending weight.
I ran across that limitation on some Learjets, in lieu of MZFW.
It included ZFW + any fuel located in the CWT...
xxx
In a 747, you could load a fuselage with "extra payload" in cabin in lieu of fuel in the CWT...
Of course, you would never be able to jettison fuel to achieve max landing weight.
Or, obviously, throw the "extra payload" out of the cabin through the doors.
Makes me laugh. I call this "experimental increase of airplane payloads".
xxx
We are quite far of the original 737 fuel system questions...
Happy contrails