Questions to B747 drivers

[givmi]

Hello I am new to the B747,

Got a few questions:

Let's imagine we have an engine failure on engine 4, would you open the crossfeed valves 1+ 4 ?...the QRH does not tell you to do this but otherwise the fuel is trapped?

Are the FMC performance predictions correct, after having lost 1 engine, if you select ENG OUT prompt on the VNAV page.

For any other non normal configuration (Flaps stuck etc) the performance predictions will of course not be correct…but is there a quick way of calculating your ETA and Fuel up on arrival.

Below is what I used so far.....but is there any faster way on the 747

Time= Distance/GS then multiply it with current FF to get Fuel required.

Fuel onboard-Fuel required= Fuel upon arrival

(if you enter your GS on the VNAV page it will give you a correct ETA?)

Thanks

[LeadSled]

givmi,
re. FMC performance figures, in my experience on both RR and GE engined -400, the engine out FMC figures are quite conservative.
Tootle pip!!

[Dufo]

You do not crossfeed fuel until you get FUEL IMBALANCE. Inventing own procedures when you have them in QRH is not the best idea.
For non standard fuel flow situations you can make gross predictions but of course do not go near reserves. With flaps or gear stuck you will not be far away from your origin/destination anyway.
It is not possible to manually enter GS on VNAV, only mach/ias.