Centre Tank Pumps for T/O
 

I think regulations require that for takeoff the engines must be supplied from a tank with two pumps.

...more a structures guy than a fuel system specialist...
But for Airbus center fuel tank means center wing box (inside the fuselage), for Boeing the center fuel tank extends to outboard of the landing gear, hence it is significantly larger and closer to the engines. For the 757 the center fuel tank has 1.5 times the capacity of both outer tanks together, for the A320 it is roughly 1/4 (!)
So the same name does not mean the same thing.

Centre Tank Pumps for T/O
 

I think the regulations require that during takeoff the engines must be supplied from tanks with two pumps.

Center Tanks Pumps for T/O
 

I think the answer can be found in this link. FAR 23.955 - Fuel Flow
Scroll down to Section 23.955 (f), Turbine engine fuel systems

http://www.risingup.com/fars/info/part23-955-FAR.shtml

It is forbidden to take off with centre tank fuel. Because in case of contamination of centre tank fuel being single source both engines may flame out.

Hi,

If the engines are not fed by the same fuel tank is a requirement for certification (according to Airbus reply), it will be nice if someone can post this requirement/regulation (EASA or FAA).

a) If there is such requirement for certification why Boeing is not complying with this regulation?

I don't think this link provide an answer to the question. In addition I think Part 23 does not apply to A320. Part 25 applies to A320.

b) I am wondering if engines are not fed by the same tank during take off in other Airbus aircraft.

Feedback appreciated.

I noticed that the new A320's in our company got the same fuel system as the A321 so with the transfer valve for the center tank. What is the whole idea behind this system? I know we dont need the center tank pumps anymore and fuel is being fed to the inner tanks by suction but why? Saves a few bucks and weight but I cant imagine that it is the only reason. It is also not very clear if this fuel can be used i.c.o. gravity feeding. Maybe someone that knows this system can clarify these things. Thanks guys

Hi The bird,
Gravity feeding simply needs the fuel to run "downhill" to the engine. The engines hang below the wing, so gravity feeding is possible from the wing tanks.
The fuel level in the centre tank will mostly be below the engines and below the fuel inlet from the wing tank, therefore gravity feeding is impossible.

Have you ever tried to syphon water from an aquarium or fuel from a tank?

FARs
 

It's a 14CFR requirement. Each engine must have a unique fuel source for take off. 14 CFR part 23 (I think).

I thought Fuel Feeding from Wing Tanks during T/O was to empty them to make Fuel returning from the IDG Cooling System not go overboard.

That makes absolute sense, the explanation I was given was that it is a regulatory requirement. What you say is an issue any stage of flight, and the central pump tank logic takes care of that.

Of course, takoff with CTR TK fuel and wings not full would be a non-standard fuel loading arrangement, but still possible. That's why the additional logic of no CTR Pump operation with slats out? Sounds good to me.

Don't know about Airbus but you'd have significant ZFW restrictions with that configuration
on a Boeing.