The aircraft has 3 independent hydraulic systems, Green, Blue and Yellow. Each system is separate and consists of a reservoir, engine driven pump, electrical pump , accumulator .
Normal operating system pressure is 3000 psi ( 200 Bar ). The electrical pumps are not an alternative for the engine driven pumps, they are used momentarily to facilitate the movement of control surfaces or landing gear in the event of a failed hydraulic system.
Hydraulic System
A Ram Air Turbine is deployed when both engines have failed, or Green + Blue or Green + Yellow is showing Low Level. The RAT may be deployed manually from the guarded button on the overhead panel. It can only be stowed on the ground.
Next
Blue System
Leak Measurement Valves (LMV) forward of the accumulators and upstream of the primary flight controls, measure any leakage in each circuit.
Gas filled accumulator to even out high frequency demand
The Blue system has 1 engine driven pump from the left engine
The Blue system has 1 electric driven pump.
Engine Shut Off Valve. Operated when the Fire button has been pressed for the left engine.
Hydraulic fluid Reservoir
Yellow System
The yellow system architecture is the same as the blue system The Yellow system engine driven pump is on the right engine.
The yellow system is used to open and close the cargo doors on the ground. When the cargo door handle is activated the yellow system electrical pump runs for a short while to open/close the cargo doors.
The Yellow system has 1 electric driven pump.
The Yellow system has 1 engine driven pump from the right engine
Green System
The Green system has 1 engine driven pump from the Left engine
The Green system has 1 engine driven pump from the Right engine
The Green system has 2 engine driven pumps f
The Green system may also be pressurized from a Ram Air Turbine pump
Engine Shut Off Valve. Operated when the Fire button has been pressed for the left and right engines They may also be operated automatically for the green system
