737 center pumps

[boeing738driver]

Hi guys,You should switch off the center pumps for take-off if u have less than 2400kgs fuel on center.i just wondering why don't we switch off the center pumps during all take-off?
Airbus recommends u that no take-off with center pumps without looking any quantity.But Boeing wants to switch off only u have less than 2400kgs.Can we do it Off during take-off like Airbus regardless the quantity???it looks more safe...
Thanks...

[BOAC]

Cannot see why you would want to, but I guess yes.

[Dutch74]

I beleive the "under 2700kg" thing is part of a AD put out by Boeing as a result of Panam 800.

If memory serves me correctly, those center tank pumps are also jettison pumps? Aren't they called Jett/Ovrd Pumps?

[G-Dawg]

hi, just wondering where your getting the 2400kg from? I know its pump off for anthing less than 460kg as stated in the Vol 2, but havn't heard anything about the 2400KG....would you be able to give me some further info as it would be very good to know....

[ansurez]

The restriction is 2300 kgs during T.O or 1400 kgs during descent with the AD 2002-24-51. The same plus, 500 Kgs during CRZ if the AD 2002-19-52.
No restrictitions apply in planes delivered since 2005.

[G-Dawg]

OK you can forget my question, done a bit of research and realized your talking about the NG, I'm on the classic, so theres the answer...thanks though.

[tropical wave]

ansurez,
You post is exactly how we operate the 737-800 center tank pumps.

[boeing738driver]

why different?

Yea we have also same procedures.But i'm asking can we switch off regardless the fuel quantity for take-off.I mean is there anybody knows what is the different of the center pumps between Airbus and Boeing.Why Airbus wants to switch off center pumps for take-off and why Boeing give us some quantity limitations?And which one is better?Thanks...

ps. ''Fly the airplane don't ask why'' It's not answer that i need...

[alexban]

I don't know about the bus ,but Boeing recommends usage of center tank fuel first,for structural reasons. The 2300 kgs restriction on the Ng is temporrary,untill all pumps are checked,and it was calculated for take-off as the minimum fuel quantity in center tank ,that won't allow the pumps to uncover in any pitch or acceleration achieved during take-off.
After constant climb is achieved,the center tank pumps can be scwitched on again.
Why would you want to take-off with center tank pumps off if above 2300 kgs?
there are differences between A and B,so don't try to operate one as the other.Different wings,fuselage,systems,etc...

[BOAC]

738 - it is a valid question, and as I said there is no real reason why you cannot do it, but why?

One airline I flew with (Classics) would leave pumps off below 1000kg, another 2000kg, to avoid asymmetric fuel feed in the climb. It is no big issue, although I prefer 2000kg as it does avoid the fuel imbalance.

[ericferret]

If as ALEXBAN says the 2300kg is the minimum to keep the pumps wet on takeoff this might well have something to do with the NG loosing fuel prime from the centre tanks. If this happens then whatever was in the tank becomes unuseable. It take a fill of about 6 tonnes in the centre to reprime the pumps. Not possible in flight.

[yachtno1]

Doesn't the A320 draw fuel from wing tanks on Take-off to avoid the problem of a contaminated centre tank?