Fuel transfer prohibition during takeoff/landing? Reference?

Re: Fuel transfer prohibition during takeoff/landing? Refere

Baronman said:
Ok...So even during crossfeed when there is only one electric fuel pump running (in the wing), "Engine driven fuel pumps will provide suction feed if the electric pumps operation is not available." The engine suction pumps are always running.

As I mentioned there are 3 electric pumps per wing, if one pump goes inop (system pressure below 6.5psi) , the plane automatically cycles to the other pumps.
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Cool - I still can't say I see a problem with that engineering then (then again, I'm not an engineer!). With the autochange logic you mentioned, it seems solid. I'd have to research write-ups, but it seems to me that this is a good system.
 
Re: Fuel transfer prohibition during takeoff/landing? Refere

Baronman said:
Ok...So even during crossfeed when there is only one electric fuel pump running (in the wing), "Engine driven fuel pumps will provide suction feed if the electric pumps operation is not available." The engine suction pumps are always running.

As I mentioned there are 3 electric pumps per wing, if one pump goes inop (system pressure below 6.5psi) , the plane automatically cycles to the other pumps.
Click to expand...

Additionally, those engine driven pumps will provide a sufficient amount of fuel up to FL250 (though I believe it's been proven to work up to the low 30's), and one electric pump can be MEL'd out of each wing (meaning you only have 2 electric pumps in each wing as opposed to 3).

If anything I'd say the system is completely over engineered. The chances of losing all six electrical pumps AND the engine driven pumps are pretty low. That'd be, what, all 8 pumps crapping the bed? At that point you've probably got much worse things to worry about, like wondering why both your wings departed the aircraft.
 
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