-
the in-line type.

 Check valve 2059GM is of the cartridge type. All other check valves in the Blue hydraulic system are of the in-line type. The two types of check valves are the same as the types which are installed in the Green hydraulic system (Ref. 29-11-00).

R **ON A/C 059-099, 102-149, 151-199, 201-299, 301-399, 401-499,
 M. Relief Valve 2063GM
 The relief valve 2063GM is installed on the HP manifold 2011GM. It is the same as the relief valve 1063GM installed in the Green hydraulic system (Ref. 29-11-00).
 N. Priority Valve 2064GM
 The priority valve 2064GM is installed on the HP manifold 2011GM. It is the same as the priority valve 1064GM installed in the Green hydraulic system (Ref. 29-11-00).

 P. Sampling Valve 2187GM
 The sampling valve 2187GM is installed on the HP manifold 2011GM. It is the same as the sampling valve 1187GM installed in the Green hydraulic system (Ref. 29-11-00).
 Q. Check Valves
 There are two types of check valve in the system. They are of:
 -
the cartridge type,

 -
the in-line type.

 One check valve is of the cartridge type. All other check valves in the Blue hydraulic system are of the in-line type. The two types of check valves are the same as the types which are installed in the Green hydraulic system (Ref. 29-11-00).
 **ON A/C ALL
 6. Operation_________
 The operation of the system is fully automatic. If necessary (because of a fault or for maintenance), it is possible to stop the automatic operation of the system.
 The electric pump automatically starts and supplies the system when any of the engines starts. The supply to the system is then continuous until the two engines stop. The electrical pump pressurizes the system to a nominal pressure of 3000 psi (206 bar). The electric pump constantly changes its output flow to that which is necessary to keep the pressure in the system stable. The system accumulator makes allowance for any temporary decrease in pressure because of the response time of the electric pump.
 If the two engines stop in flight, the electric pump of the blue system will continue to operate if the supply of AC power comes from the APU. In this case, compression of the nose landing gear stops the electric pump. A time delay circuit keeps the electric pump in operation for two minutes after compression of the nose landing gear. This makes sure that the electric pump does not stop immediately when the aircraft lands.
 If there is a total failure of the AC power supply (which causes the electric pump to stop), the RAT automatically operates and pressurizes the system. It is also possible to operate the RAT from the flight compartment (Ref. 29-22-00).

 The system has temperature and pressure sensors installed in different places. They continuously monitor the condition of the system. The sensors send information to the flight compartment. The ECAM displays show the information as FAULT warnings on the overhead panel (Ref. 29-30-00).
 If the electric pump motor overheats, the temperature switch in the motor sends signals to the ECAM and overhead panel. The message "ELEC OVHT" appears on the lower display unit (DU) of the ECAM and the BLUE ELEC PUMP/FAULT light comes on. The applicable messages appear on the ECAM upper DU STATUS page. When the temperature decreases the warnings stop and a message on the STATUS page gives the information that the pump is available.
 Two pushbutton switches (P/BSW) in the flight compartment control the operation of the electric pump. The BLUE ELEC PUMP P/BSW 2704GJ is on the overhead panel 40VU. The crew members use it to stop the pump when there is a fault. It is usually set to AUTO and has the legends FAULT and OFF which come on as necessary. The BLUE PUMP OVRD P/BSW 2703GJ is on the maintenance panel 50VU. The legend ON on the P/BSW comes on when applicable. The P/BSW makes it possible to start the electric pump on the ground when the engines are not in operation.
 Operation of the electric pump with the P/BSW 2703GJ is only possible when the P/BSW 2704GJ is also set to AUTO. One operation (press and release) of the P/BSW 2703GJ starts the electric pump. A legend ON on the P/BSW comes on to show that the electric pump is in operation. To stop the pump it is necessary to press and release the P/BSW 2703GJ again. One more possibility is to set the P/BSW 2704GJ to the OFF position. This cancels the ON function of the P/BSW 2703GJ at the same time. It is then necessary to set the P/BSW 2704GJ to its AUTO position (press in) for normal operation.
 The P/BSW 1884GP which is also on the maintenance panel 50VU controls the solenoid valve 2150GP of the leakage measurement system. This P/BSW is for maintenance use only (Ref. 29-19-00).

 BLUE MAIN HYDRAULIC POWER - ADJUSTMENT/TEST
　
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