PPRuNe Forums - A330-343 Blue Elec Hyd Pump question, need help please.

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A330-343 Blue Elec Hyd Pump question, need help please.

I'm new to this forums and i'm soory if this question had beed asked, but i can't find it.

The A330 FCOM state that

Quote:

A pump, driven by Engine 1, pressurizes the blue system.
A manually-controlled electric pump can also pressurize the system.
In the event of an Engine 1 failure, in addition to a PRIM 1 or PRIM 3 loss : The BLUE ELEC
PUMP runs automatically in flight to ensure sufficient authority on the electrical rudder, thereby
counteracting the yaw sideslip induced by asymetrical thrust.

I've wonder why there is no automatically activated in yellow elec pump in case of Engine 2 failure, and PRIM 1 or 2 loss.

IMO I think that the blue one with prim 1 or 3 loss is worst case. Be cause
the rudder control said that PRIM 3 can replace PRIM 2 in case of PRIM 2 loss.

http://i.imgur.com/wT1WgLd.png

Can anyone please help me with this question.

Sorry for my English.

I have also another question:
In the ARCHITECTURE above if P1 fails S1 takes over, so redundancy for rudder is still there. So why Blue Elec pumps starts again?
In another word, after ENG1 failure, the effect of PRIM 1 and PRIM 3 failures are not same. If PRIM 3 fails, no redundancy; if PRIM 1 fails there is still redundancy...(?)

Just a thought... Rudder authority is most important at low speed. In case of Engine 2 failure at low speed i.e. when the flaps are out, Yellow Elec pump is running anyway, thus giving more authority and redundancy to the rudder. No need for extra logic to activate it.

Blue autorun only came about with the electric rudder mod. Older 330s with the mechanical cable rudder did not have this.