I've asked this before, but no answer so am going to ask again. Hope fully someone will answer...
In the 747 Classic, after Fuel tanks 2 & 3 are EQUAL to the fuel in tanks 1 & 4 PLUS reserves, we burn tank to engine leaving a crossfeed valve open.
Now, some operators leave #2 open, some leave #1 or #4 crossfeed open, and some leave both #1 & #4 crossfeed open.
Now here is the question....
What is the advantage of leaving #1 and/or #4 open vs. leaving #2 open.
The way I see it, I would rather leave #2 open. The logic being if I develop a fuel leak in the xfeed manifold. It is going to cost me fuel from an inbd tank that I can easily fix using the dump manifold or do nothing because the fuel imbalance on inbd tanks is negligible.
So what am I missing? Someone.....anyone......Bueller?
