Originally Posted by
dutch747
I would guess your right. But what advantage does leaving #1 or #4 give you?
Only thing I can think of, you always takeoff in a Modified configuration in a 100 and a 200 (if you are less than 17K in the center tank) to ensure the manifold is positively pressurized. If one of the outbd crossfeed valves fails in the open position you can still crossfeed to engines 1 & 4. Once you go to tank to engine you close three of them. By leaving 1 or 4 open, if you would lose power to the boost pumps, 1 & 4 sit higher and would be able to gravity feed the manifold until power is restored.
That is the best I can do. But thanks for bringing it up. I have recurrent next month. A good time to get back in the books.
