Hi Tyro
That is what I wonder. If I kept indefinitely using only one tank to feed both engines, this tank would deplete. Then we would have a gravity feeding in the full tank with no pumps (which is not the end of the world) and an imbalance (neither is this) but also the engine in the opposite side would starve because there is no fuel in its associated tank and the line can't be pressurized from the other side.
In the 320, the OEI case of gravity feed permits feeding an engine from the opposite tank. There is something similar in the 330. I guess it could work, as it's been suggested. But it is not in the Airbus published procedures… And it seems too complicated anyway.
What intrigues me is: What does the "WHEN L(R) TK FUEL REQRD" line exactly mean in a pumps lost ECAM actions?
I wouldn't desire to deplete a tank only to delay gravity feeding. I would start the gravity feeding well before that. My question is: When is the best moment to do it?