DOC AIRBUS | AMM A320FBLUE MAIN HYDRAULIC POWER - DESCRIPTION AND OPERATION
** ON A/C NOT FOR ALL
** ON A/C NOT FOR ALL
1. General
The Blue hydraulic system is one of the three systems which supply the aircraft with hydraulic power. The system supplies some flight controls and also the Constant Speed Motor/Generator (CSM/G) when it is necessary.
Most of the components of the system are installed in the Blue hydraulic compartment. The compartment is in the left-hand belly fairing, forward of the main landing-gear compartment. The reservoir and the Low Pressure (LP) filter are not in the hydraulic compartment. They are in the left-hand belly fairing aft of the main landing-gear compartment. The Blue hydraulic system is hydraulically isolated from the other two primary systems. It is not possible for hydraulic fluid to go from one system to a different system.
The system operates at a nominal pressure of 3000 psi (206 bar). It can supply 32 l/min (8.45 USgal/min) from the electric pump. The return (LP) part of the system is pressurized to 50 psi (3.5 bar). It is possible to pressurize the High Pressure (HP) system from one of three different sources:
Operation of the system is usually automatic, but the crew can control parts of the system from the flight compartment if necessary.
The Electronic Centralized Aircraft-Monitor (ECAM) system monitors the condition of the system all of the time. When there is a fault or when the crew select it, system information is shown in the flight compartment.
** ON A/C NOT FOR ALL The Blue hydraulic system is one of the three systems which supply the aircraft with hydraulic power. The system supplies some flight controls and also the Constant Speed Motor/Generator (CSM/G) when it is necessary.
Most of the components of the system are installed in the Blue hydraulic compartment. The compartment is in the left-hand belly fairing, forward of the main landing-gear compartment. The reservoir and the Low Pressure (LP) filter are not in the hydraulic compartment. They are in the left-hand belly fairing aft of the main landing-gear compartment. The Blue hydraulic system is hydraulically isolated from the other two primary systems. It is not possible for hydraulic fluid to go from one system to a different system.
The system operates at a nominal pressure of 3000 psi (206 bar). It can supply 32 l/min (8.45 USgal/min) from the electric pump. The return (LP) part of the system is pressurized to 50 psi (3.5 bar). It is possible to pressurize the High Pressure (HP) system from one of three different sources:
- the electric pump
- the Ram Air Turbine (RAT) (Ref. AMM D/O 29-22-00-00)
- the ground supply connections.
Operation of the system is usually automatic, but the crew can control parts of the system from the flight compartment if necessary.
The Electronic Centralized Aircraft-Monitor (ECAM) system monitors the condition of the system all of the time. When there is a fault or when the crew select it, system information is shown in the flight compartment.
2. Component Location
Blue Hydraulic System - Component Location - Sheet 1
Blue Hydraulic System - Component Location - Sheet 1
Blue Hydraulic System - Component Location - Sheet 1 ** ON A/C NOT FOR ALL
Blue Hydraulic System - Component Location - Sheet 1 ** ON A/C NOT FOR ALL
Blue Hydraulic System - Component Location - Sheet 1 ** ON A/C NOT FOR ALL
Component Location - Sheet 2
Blue Hydraulic System - Component Location - Sheet 2
Blue Hydraulic System - Component Location - Sheet 2 ** ON A/C NOT FOR ALL
Blue Hydraulic System - Component Location - Sheet 2 ** ON A/C NOT FOR ALL
Blue Hydraulic System - Component Location - Sheet 3 ** ON A/C NOT FOR ALL
Blue Hydraulic System - Component Location - Sheet 3 ** ON A/C NOT FOR ALL
** ON A/C NOT FOR ALL Blue Hydraulic System - Component Location - Sheet 1 Blue Hydraulic System - Component Location - Sheet 1 Blue Hydraulic System - Component Location - Sheet 1 ** ON A/C NOT FOR ALL Blue Hydraulic System - Component Location - Sheet 1 ** ON A/C NOT FOR ALL Blue Hydraulic System - Component Location - Sheet 1 ** ON A/C NOT FOR ALL Component Location - Sheet 2 Blue Hydraulic System - Component Location - Sheet 2 Blue Hydraulic System - Component Location - Sheet 2 ** ON A/C NOT FOR ALL Blue Hydraulic System - Component Location - Sheet 2 ** ON A/C NOT FOR ALL Blue Hydraulic System - Component Location - Sheet 3 ** ON A/C NOT FOR ALL Blue Hydraulic System - Component Location - Sheet 3 ** ON A/C NOT FOR ALL | FIN | FUNCTIONAL DESIGNATION | PANEL | ZONE | ACCESS DOOR | ATA REF |
|---|---|---|---|---|---|
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| 2075GJ | PACKAGE E-PUMP | 195BB | 195 | 29-12-51 | |
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| 2050GM | CHECK VALVE B | 195BB | 195 | 29-12-36 | |
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| 2048GM | HP-FILTER B | 195BB | 195 | 29-12-45 | |
| 2084GM | CASE DRAIN FILT.ELEC.PUMP B | 195BB | 195 | 29-12-43 | |
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| 2041GM | CHECK VALVE B | 195BB | 195 | 27-20-00 | |
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| 2000GQ | RESERVOIR BLUE | 197EB | 197 | 29-12-41 | |
| 2002GM | LP FILTER B | 197 | 29-12-44 | ||
| 2006GM | GND CNCTR-SELF SEAL. | 197EB | 197 | 27-20-00 | |
| 2008GM | GND CNCTR-SELF SEAL. | 197EB | 197 | 27-20-00 | |
| 2022GM | CHECK VALVE G | 195BB | 195 | 27-20-00 | |
| 2040GM | CHECK VALVE B | 145 | 27-20-00 | ||
| 2063GM | RELIEF VALVE B SYS | 195BB | 195 | 29-12-32 | |
| 2064GM | PRIORITY VALVE | 146 | 29-12-33 | ||
| 2070GM | HYD ACCU BLUE | 195BB | 195 | 29-12-42 | |
| 2071GM | N2 CHARGING VALVE | 195BB | 195 | 29-12-22 | |
| 2072GM | B SYS ACCU PRESS GAGE | 195BB | 195 | 29-12-21 | |
| 2092GM | DAMPENER-B.-SYS. | 195BB | 195 | 29-12-46 | |
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| 2075GJ | PACKAGE E-PUMP | 195 | 29-12-51 | ||
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| 2048GM | HP-FILTER B | 195 | 29-12-45 | ||
| 2084GM | CASE DRAIN FILT.ELEC.PUMP B | 195 | 29-12-43 | ||
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| 2041GM | CHECK VALVE B | 195 | 27-20-00 | ||
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| 2144GM | CHECK VALVE B | 145 | 27-20-00 | ||
| 2170GM | CHECK VALVE-FLAP WTB B RETURN, L WING | 575DB | 500 | 29-12-37 | |
| 2187GM | SAMPLING-V.-B.-SYS. | 195BB | 195 | 29-12-34 | |
| 2264GM | BLUE RSVR DRAIN VALVE | 197EB | 197 | 29-12-35 | |
| 2405GM | CHECK VALVE-FLAP WTB B RETURN, R WING | 675DB | 600 | 29-12-37 | |
| 2410GM | CHECK VALVE-SLAT WTB B RETURN, L WING | 522SB | 500 | 29-12-37 | |
| 2411GM | CHECK VALVE-SLAT WTB B RETURN, R WING | 622SB | 600 | 29-12-37 | |
| 2467GM | CHECK VALVE B | 148 | 27-20-00 | ||
| 2706GJ | CURRENT TRANSFORMER | 122 | 29-12-15 | ||
| 2707GJ | CURRENT UNBAL.DETECT. | 122 | 29-12-18 | ||
3. System Description
Blue Hydraulic System - Schematic ** ON A/C NOT FOR ALL
Blue Hydraulic System - Schematic ** ON A/C NOT FOR ALL
Blue Hydraulic System - Schematic ** ON A/C NOT FOR ALL
The Blue hydraulic system is made up of two primary parts:
The electric pump 2075GJ usually pressurizes the HP circuit. The electric pump is installed in the Blue hydraulic compartment. An acoustic filter is part of the suction pipe to the electric pump. A pulsation dampener 2092GM is installed immediately downstream of the electric pump in the HP line. It smooths the output from the electric pump.
The suction, pressure and case drain lines connected to the electric pump are all flexible hoses. There is a self-sealing connection on the suction line and check valves in the pressure and case drain lines. Together, they make it possible to replace the electric pump without a large loss of fluid. Anti-vibration mounts support the electric pump.
The Blue hydraulic system has two primary parts:
The electric pump 2075GJ usually pressurizes the HP circuit. The electric pump is installed in the Blue hydraulic compartment. An acoustic filter is part of the suction pipe to the electric pump.
The suction, pressure and case drain lines connected to the electric pump are all flexible hoses. There is a self-sealing connection on the suction line and check valves in the pressure and case drain lines. Together, they make it possible to replace the electric pump without a large loss of fluid. Anti-vibration mounts hold the electric pump.
The electric pump starts automatically when one of the engines starts. It then operates continuously until the two engines are stopped. A pushbutton (P/B) switch in the flight compartment makes it possible for the crew to stop the electric pump.
It is also possible to pressurize the system with the electric pump when the engines are stopped. A P/B switch on the maintenance panel 50VU in the flight compartment stops the automatic function and starts the electric pump.
The case drain fluid from the electric pump assembly goes to the LP circuit through a check valve 2041GM and a filter 2084GM. The seal drain fluid goes through a connection into the seal drain system (Ref. AMM D/O 29-17-00-00).
A current transformer 2706GJ and a current unbalance detector 2707GJ together give protection if there is a fault in the electric pump motor. If a fault occurs, they stop the motor. A temperature switch is included in the motor. If the temperature of the motor is too high, the switch sends a signal to the ECAM and warning systems.
The Ram Air Turbine (RAT) can also supply the Blue hydraulic system with HP fluid (Ref. AMM D/O 29-22-00-00). The RAT operates automatically if there is a total AC failure. It is also possible to operate the RAT from the flight compartment.
On the ground, it is possible to pressurize the system from a ground supply. The system has self-sealing connections for a ground supply. They are installed on the ground service panel of the Blue hydraulic system.
The ground service panel for the Blue hydraulic system is in the left-hand belly fairing, aft of the main landing-gear compartment. The components and connections which are necessary to service the Blue hydraulic system (not including the pressurization connection for the reservoir) are installed together in a group on it. The ground service panel has these components on it:
The supply to all of the consumers goes through the HP manifold 2111GM. The supply to all of the consumers (other than the slat motor and CSM/G) also goes through the Leakage Measurement System (LMS) manifold.
The HP manifold has ports which connect it to other parts of the system as follows:
The supply to all of the consumers goes through the HP manifold 2111GM.
The HP manifold has ports which connect it to other parts of the system as follows:
Also installed downstream of the electric pump on the HP manifold 2111GM are:
The supply to all of the consumers goes through the HP manifold.
The HP manifold has ports which connect it to other parts of the system as follows:
The supply to all of the consumers goes through the HP manifold.
The HP manifold has ports which connect it to other parts of the system as follows:
A pressure relief valve 2063GM installed on the HP manifold prevents too much pressure in the system. The pressure relief valve opens when the pressure increases to 237 bar (3436 psi). It closes when the pressure decreases to 220 bar (3190 psi).
Two pressure switches 2151GN and 10CE-1 on the HP manifold monitor the pressure in the system. The pressure switch 2151GN sends data to the ECAM and warning systems. The pressure switch 10CE-1 sends data to the flight control system only. A pressure transmitter 2065GN transmits pressure data to the ECAM and warning system.
A solenoid valve 2150GP in the HP manifold controls the flow of the hydraulic fluid to the flight controls in the rear section, the LH wing and the RH wing. The solenoid valve is operated from the maintenance overhead panel 50VU in the flight compartment. A HP filter 2048GM is installed on the system pressure inlet of the HP manifold. The filtration rate of the filter is 15 microns.
A pressure relief valve 2063GM installed on the HP manifold prevents too much pressure in the system. The pressure relief valve opens when the pressure increases to 237 bar (3436 psi). It closes when the pressure decreases to 220 bar (3190 psi).
Two pressure switches 2151GN and 10CE-1 on the HP manifold monitor the pressure in the system. The pressure switch 2151GN sends data to the ECAM and warning systems. The pressure switch 10CE-1 sends data to the flight control system only. A pressure transmitter 2065GN transmits pressure data to the ECAM and warning system.
The sampling valve 2187GM is installed on the HP manifold. It makes it possible to get samples of the system fluid for analysis. It is possible to take the sample with the system at full pressure.
The priority valve 2064GM is also installed on the HP manifold. It stops the supply of fluid to non-essential consumers (slats and CSM/G) if the pressure in the system is too low. The priority valve closes (and stops the supply) when the pressure decreases to 130 +0 -3 bar (1885 +10 -43 psi). The valve opens when the pressure increases to 140 +0 -5 bar (2030 +0 -72,5 psi).
Check valves are installed on the HP manifold to control the flow of fluid to and from the manifold.
The system accumulator 2070GM has a direct connection to the HP manifold. The accumulator keeps the pressure in the system free from small changes. It also makes a supply of fluid available to replace a temporary decrease. This can occur if there is a sudden large demand and the pump has not had time to adjust. The accumulator is pre-charged with nitrogen to 1885 psi (130 bar). It holds 0.18 l (0.0476 USgal) of useable fluid when it is full (at 3000 psi (206 bar)). A gas charging valve 2071GM and a pressure gage 2072GM are installed on the accumulator.
The LMS manifold 2146GM makes it possible to measure the internal leakage of groups of consumers. The HP supply is divided into three outputs, one to each of:
The priority valve 2064GM is also installed on the HP manifold. It stops the supply of hydraulic fluid to non-essential consumers (slats and CSM/G) if the pressure in the system is too low. The priority valve closes (and stops the supply) when the pressure decreases to 130 +0 -3 bar (1885 +10 -43 psi). The valve opens when the pressure increases to 140 +0 -5 bar (2030 +0 -72,5 psi).
Check valves are installed on the HP manifold to control the flow of hydraulic fluid to and from the manifold.
The system accumulator 2070GM has a direct connection to the HP manifold. The accumulator keeps the pressure in the system free from small changes. It also makes a supply of hydraulic fluid available to replace a temporary decrease. This can occur if there is a sudden large demand and the pump has not had time to adjust. The accumulator is pre-charged with nitrogen to 1885 psi (130 bar). It holds 0.18 l (0.0476 USgal) of useable hydraulic fluid when it is full (at 3000 psi (206 bar)). A gas charging valve 2071GM and a pressure gage 2072GM are installed on the accumulator.
The ultrasonic flowmeter (USF) makes it possible to measure the internal leakage of groups of consumers. The HP hydraulic supply through the solenoid valve 2150GP is divided into three outputs, one to each of:
The Blue hydraulic system supplies these consumers:
It is possible to supply all of the consumers from the ground supply connections.
The internal leakage is measured with the hydraulic supply from the Blue electric pump and the ultrasonic flowmeter (USF) (Ref. AMM D/O 29-19-00-00).
The Blue hydraulic system supplies these consumers:
It is possible to supply all of the consumers from the ground supply connections.
The LP circuit returns the fluid from the consumers to the reservoir. The case drain of the electric pump and the return from the HP manifold are also connected to the LP circuit. Check valves are installed in the system. They control the flow of fluid in the system. The check valves also give protection to the main system if a sub-system has a leak. Part of the LP circuit is also used in the reservoir filling system (Ref. AMM D/O 29-16-00-00).
The LP fluid goes through the LP filter 2002GM immediately before it gets to the reservoir. The filter has a filtration rating of 3 microns. If the filter element clogs, a by-pass operates and unfiltered fluid goes to the reservoir. A temperature sensor 2381GR attached to the outlet of the LP filter monitors the temperature of the fluid. The temperature information is sent to the ECAM and warning systems (Ref. AMM D/O 29-33-00-00). The LP filter is installed in the left-hand belly fairing, aft of the main landing-gear compartment.
A filter 2084GM is installed in the case drain line of the electric pump which goes to the LP circuit. The filter has a filtration rating of 15 microns.
The system reservoir 2000GQ is installed in the left-hand belly fairing aft of the main landing-gear compartment together with the LP filter. The reservoir holds a supply of fluid. It also makes allowance for differences in the quantity of fluid in the system (because of changes in the positions of jacks, for example).
The reservoir is filled through the reservoir filling system (Ref. AMM D/O 29-16-00-00) which is operated from the ground service panel of the Green hydraulic system. A reservoir drain valve is installed on the ground service panel of the Blue hydraulic system.
The reservoir is pressurized with air to 3.5 bar (50 psi) (to stop cavitation at the inlet to the electric pump). The supply of air comes from the aircraft pneumatic system (Ref. AMM D/O 36-00-00-00). It is also possible to pressurize the reservoir from a ground supply (Ref. AMM D/O 29-14-00-00). A depressurization valve 2087GM is installed on the ground service panel of the Blue hydraulic system. A pressure relief valve 2005GM and a pressure gage 2383GM are installed on the the reservoir.
** ON A/C NOT FOR ALL Blue Hydraulic System - Schematic ** ON A/C NOT FOR ALL Blue Hydraulic System - Schematic ** ON A/C NOT FOR ALL Blue Hydraulic System - Schematic ** ON A/C NOT FOR ALL The Blue hydraulic system is made up of two primary parts:
- a HP circuit which supplies the consumers
- a LP or return circuit through which fluid returns to the reservoir.
The electric pump 2075GJ usually pressurizes the HP circuit. The electric pump is installed in the Blue hydraulic compartment. An acoustic filter is part of the suction pipe to the electric pump. A pulsation dampener 2092GM is installed immediately downstream of the electric pump in the HP line. It smooths the output from the electric pump.
The suction, pressure and case drain lines connected to the electric pump are all flexible hoses. There is a self-sealing connection on the suction line and check valves in the pressure and case drain lines. Together, they make it possible to replace the electric pump without a large loss of fluid. Anti-vibration mounts support the electric pump.
The Blue hydraulic system has two primary parts:
- a HP circuit which supplies the consumers
- a LP or return circuit through which fluid returns to the reservoir.
The electric pump 2075GJ usually pressurizes the HP circuit. The electric pump is installed in the Blue hydraulic compartment. An acoustic filter is part of the suction pipe to the electric pump.
The suction, pressure and case drain lines connected to the electric pump are all flexible hoses. There is a self-sealing connection on the suction line and check valves in the pressure and case drain lines. Together, they make it possible to replace the electric pump without a large loss of fluid. Anti-vibration mounts hold the electric pump.
The electric pump starts automatically when one of the engines starts. It then operates continuously until the two engines are stopped. A pushbutton (P/B) switch in the flight compartment makes it possible for the crew to stop the electric pump.
It is also possible to pressurize the system with the electric pump when the engines are stopped. A P/B switch on the maintenance panel 50VU in the flight compartment stops the automatic function and starts the electric pump.
The case drain fluid from the electric pump assembly goes to the LP circuit through a check valve 2041GM and a filter 2084GM. The seal drain fluid goes through a connection into the seal drain system (Ref. AMM D/O 29-17-00-00).
A current transformer 2706GJ and a current unbalance detector 2707GJ together give protection if there is a fault in the electric pump motor. If a fault occurs, they stop the motor. A temperature switch is included in the motor. If the temperature of the motor is too high, the switch sends a signal to the ECAM and warning systems.
The Ram Air Turbine (RAT) can also supply the Blue hydraulic system with HP fluid (Ref. AMM D/O 29-22-00-00). The RAT operates automatically if there is a total AC failure. It is also possible to operate the RAT from the flight compartment.
On the ground, it is possible to pressurize the system from a ground supply. The system has self-sealing connections for a ground supply. They are installed on the ground service panel of the Blue hydraulic system.
The ground service panel for the Blue hydraulic system is in the left-hand belly fairing, aft of the main landing-gear compartment. The components and connections which are necessary to service the Blue hydraulic system (not including the pressurization connection for the reservoir) are installed together in a group on it. The ground service panel has these components on it:
- the ground test suction and delivery connectors 2006GM and 2008GM
- the depressurization valve 2087GM of the reservoir
- the drain valve 2264GM of the reservoir
- the RAT control panel.
The supply to all of the consumers goes through the HP manifold 2111GM. The supply to all of the consumers (other than the slat motor and CSM/G) also goes through the Leakage Measurement System (LMS) manifold.
The HP manifold has ports which connect it to other parts of the system as follows:
- a system pressure inlet from the pump, RAT and ground supply
- two outlets to the LMS manifold
- one outlet to the slat motor and CSM/G
- one outlet to the RAT
- one connection to/from the system accumulator 2070GM
- one outlet to the return (LP) circuit.
The supply to all of the consumers goes through the HP manifold 2111GM.
The HP manifold has ports which connect it to other parts of the system as follows:
- a system pressure inlet from the pump, RAT and ground supply
- one outlet to the flight controls in the rear section, the LH wing and the RH wing
- one outlet is plugged
- one outlet to the slat motor and CSM/G
- one outlet to the RAT
- one connection to/from the system accumulator 2070GM
- one outlet to the return (LP) circuit.
Also installed downstream of the electric pump on the HP manifold 2111GM are:
- the pressure switch 2074GJ
- the switch manifold 2380GM with an integrated check valve.
The supply to all of the consumers goes through the HP manifold.
The HP manifold has ports which connect it to other parts of the system as follows:
- a system pressure inlet from the pump, RAT and ground supply
- one outlet to the flight controls in the rear section, the LH wing and the RH wing
- one outlet is plugged
- one outlet to the slat motor and CSM/G
- one outlet to the RAT
- one connection to/from the system accumulator 2070GM
- one outlet to the return (LP) circuit.
- the pressure switch 2074GJ
- the switch manifold 2380GM with an integrated check valve.
The supply to all of the consumers goes through the HP manifold.
The HP manifold has ports which connect it to other parts of the system as follows:
- a system pressure inlet from the pump, RAT and ground supply
- one outlet to the flight controls in the rear section, the LH wing and the RH wing
- one outlet is plugged
- one outlet to the slat motor and CSM/G
- one outlet to the RAT
- one connection to/from the system accumulator 2070GM
- one outlet to the return (LP) circuit.
A pressure relief valve 2063GM installed on the HP manifold prevents too much pressure in the system. The pressure relief valve opens when the pressure increases to 237 bar (3436 psi). It closes when the pressure decreases to 220 bar (3190 psi).
Two pressure switches 2151GN and 10CE-1 on the HP manifold monitor the pressure in the system. The pressure switch 2151GN sends data to the ECAM and warning systems. The pressure switch 10CE-1 sends data to the flight control system only. A pressure transmitter 2065GN transmits pressure data to the ECAM and warning system.
A solenoid valve 2150GP in the HP manifold controls the flow of the hydraulic fluid to the flight controls in the rear section, the LH wing and the RH wing. The solenoid valve is operated from the maintenance overhead panel 50VU in the flight compartment. A HP filter 2048GM is installed on the system pressure inlet of the HP manifold. The filtration rate of the filter is 15 microns.
A pressure relief valve 2063GM installed on the HP manifold prevents too much pressure in the system. The pressure relief valve opens when the pressure increases to 237 bar (3436 psi). It closes when the pressure decreases to 220 bar (3190 psi).
Two pressure switches 2151GN and 10CE-1 on the HP manifold monitor the pressure in the system. The pressure switch 2151GN sends data to the ECAM and warning systems. The pressure switch 10CE-1 sends data to the flight control system only. A pressure transmitter 2065GN transmits pressure data to the ECAM and warning system.
The sampling valve 2187GM is installed on the HP manifold. It makes it possible to get samples of the system fluid for analysis. It is possible to take the sample with the system at full pressure.
The priority valve 2064GM is also installed on the HP manifold. It stops the supply of fluid to non-essential consumers (slats and CSM/G) if the pressure in the system is too low. The priority valve closes (and stops the supply) when the pressure decreases to 130 +0 -3 bar (1885 +10 -43 psi). The valve opens when the pressure increases to 140 +0 -5 bar (2030 +0 -72,5 psi).
Check valves are installed on the HP manifold to control the flow of fluid to and from the manifold.
The system accumulator 2070GM has a direct connection to the HP manifold. The accumulator keeps the pressure in the system free from small changes. It also makes a supply of fluid available to replace a temporary decrease. This can occur if there is a sudden large demand and the pump has not had time to adjust. The accumulator is pre-charged with nitrogen to 1885 psi (130 bar). It holds 0.18 l (0.0476 USgal) of useable fluid when it is full (at 3000 psi (206 bar)). A gas charging valve 2071GM and a pressure gage 2072GM are installed on the accumulator.
The LMS manifold 2146GM makes it possible to measure the internal leakage of groups of consumers. The HP supply is divided into three outputs, one to each of:
- the flight controls in the LH wing
- the flight controls in the RH wing
- the flight controls in the tail section.
The priority valve 2064GM is also installed on the HP manifold. It stops the supply of hydraulic fluid to non-essential consumers (slats and CSM/G) if the pressure in the system is too low. The priority valve closes (and stops the supply) when the pressure decreases to 130 +0 -3 bar (1885 +10 -43 psi). The valve opens when the pressure increases to 140 +0 -5 bar (2030 +0 -72,5 psi).
Check valves are installed on the HP manifold to control the flow of hydraulic fluid to and from the manifold.
The system accumulator 2070GM has a direct connection to the HP manifold. The accumulator keeps the pressure in the system free from small changes. It also makes a supply of hydraulic fluid available to replace a temporary decrease. This can occur if there is a sudden large demand and the pump has not had time to adjust. The accumulator is pre-charged with nitrogen to 1885 psi (130 bar). It holds 0.18 l (0.0476 USgal) of useable hydraulic fluid when it is full (at 3000 psi (206 bar)). A gas charging valve 2071GM and a pressure gage 2072GM are installed on the accumulator.
The ultrasonic flowmeter (USF) makes it possible to measure the internal leakage of groups of consumers. The HP hydraulic supply through the solenoid valve 2150GP is divided into three outputs, one to each of:
- the flight controls in the LH wing
- the flight controls in the RH wing
- the flight controls in the tail section.
The Blue hydraulic system supplies these consumers:
- from the HP manifold (downstream of the priority valve):
- the LH slat Power Control Unit (PCU) motor
- the CSM/G.
- from the HP manifold, through the LMS manifold (upstream of the priority valve):
- the LH and RH spoiler 3
- the LH and RH ailerons
- the LH and RH slat Wing Tip Brake (WTB)
- the LH and RH flap (WTB)
- the LH and RH elevators
- the rudder.
- from the HP manifold, upstream of the LMS manifold and priority valve:
- the RAT.
NOTE: The supply to the RAT is for ground test and retraction of the RAT when the aircraft is on the ground only.
It is possible to supply all of the consumers from the ground supply connections.
The internal leakage is measured with the hydraulic supply from the Blue electric pump and the ultrasonic flowmeter (USF) (Ref. AMM D/O 29-19-00-00).
The Blue hydraulic system supplies these consumers:
- From the HP manifold, downstream of the priority valve:
- The left slat Power Control Unit (PCU) motor
- The CSM/G.
- From the HP manifold, through the solenoid valve 2150GP and upstream of the priority valve:
- The left and right spoiler 3
- The left and right ailerons
- The left and right slat Wing Tip Brake (WTB)
- The left and right flap (WTB)
- The left and right elevators
- The rudder.
- From the HP manifold, upstream of the solenoid valve 2150GP and the priority valve:
- The RAT.
NOTE: The supply to the RAT is for ground test and retraction of the RAT when the aircraft is on the ground only.
It is possible to supply all of the consumers from the ground supply connections.
The LP circuit returns the fluid from the consumers to the reservoir. The case drain of the electric pump and the return from the HP manifold are also connected to the LP circuit. Check valves are installed in the system. They control the flow of fluid in the system. The check valves also give protection to the main system if a sub-system has a leak. Part of the LP circuit is also used in the reservoir filling system (Ref. AMM D/O 29-16-00-00).
The LP fluid goes through the LP filter 2002GM immediately before it gets to the reservoir. The filter has a filtration rating of 3 microns. If the filter element clogs, a by-pass operates and unfiltered fluid goes to the reservoir. A temperature sensor 2381GR attached to the outlet of the LP filter monitors the temperature of the fluid. The temperature information is sent to the ECAM and warning systems (Ref. AMM D/O 29-33-00-00). The LP filter is installed in the left-hand belly fairing, aft of the main landing-gear compartment.
A filter 2084GM is installed in the case drain line of the electric pump which goes to the LP circuit. The filter has a filtration rating of 15 microns.
The system reservoir 2000GQ is installed in the left-hand belly fairing aft of the main landing-gear compartment together with the LP filter. The reservoir holds a supply of fluid. It also makes allowance for differences in the quantity of fluid in the system (because of changes in the positions of jacks, for example).
The reservoir is filled through the reservoir filling system (Ref. AMM D/O 29-16-00-00) which is operated from the ground service panel of the Green hydraulic system. A reservoir drain valve is installed on the ground service panel of the Blue hydraulic system.
The reservoir is pressurized with air to 3.5 bar (50 psi) (to stop cavitation at the inlet to the electric pump). The supply of air comes from the aircraft pneumatic system (Ref. AMM D/O 36-00-00-00). It is also possible to pressurize the reservoir from a ground supply (Ref. AMM D/O 29-14-00-00). A depressurization valve 2087GM is installed on the ground service panel of the Blue hydraulic system. A pressure relief valve 2005GM and a pressure gage 2383GM are installed on the the reservoir.
4. Power Supply
** ON A/C NOT FOR ALL 5. Component Description
A. Reservoir FIN: 2000-GQ
The reservoir 2000GQ is made of two molded light alloy sections which are welded together to make a cylindrical shape. The top of the reservoir has a manifold for the components of the reservoir pressurization system (Ref. 29-14-00). The bottom of the reservoir has three ports for the hydraulic connections. The connections are for:
The drain valve is on the ground service panel, not on the reservoir as in the Green and Yellow hydraulic systems. The reservoir also has flanges to attach the quantity indicator/transmitter and the low level switch (Ref. AMM D/O 29-31-00-00).
The inside of the reservoir has baffles which give a supply of fluid for 20 s under negative 'g' conditions. The baffles also form an anti-emulsion device which limits the emulsion of the fluid when there is a large return flow.
The hydraulic fluid capacities of the reservoir are:
The reservoir is pressurized to 50 psi (3.5 bar) relative, and is sealed to hold the pressure when there is no supply of air (for example, when the aircraft is parked). It is possible to pressurize the reservoir from a ground supply (Ref. AMM D/O 29-14-00-00).
The reservoir is filled with fluid through the reservoir filling system (Ref. 29-16-00).
The reservoir 2000GQ is made of two molded light alloy sections which are welded together to make a cylindrical shape. The top of the reservoir has a manifold for the components of the reservoir pressurization system (Ref. 29-14-00). The bottom of the reservoir has three ports for the hydraulic connections. The connections are for:
- the suction line,
- the return line,
- the drain line.
The drain valve is on the ground service panel, not on the reservoir as in the Green and Yellow hydraulic systems. The reservoir also has flanges to attach the quantity indicator/transmitter and the low level switch (Ref. AMM D/O 29-31-00-00).
The inside of the reservoir has baffles which give a supply of fluid for 20 s under negative 'g' conditions. The baffles also form an anti-emulsion device which limits the emulsion of the fluid when there is a large return flow.
The hydraulic fluid capacities of the reservoir are:
- the normal fill level 6 l (1.5850 USgal),
- the maximum gageable level 8 l (2.1134 USgal),
- the low-level warning between 2.0 and 2.3 l (0.52 and 0.6 USgal).
The reservoir is pressurized to 50 psi (3.5 bar) relative, and is sealed to hold the pressure when there is no supply of air (for example, when the aircraft is parked). It is possible to pressurize the reservoir from a ground supply (Ref. AMM D/O 29-14-00-00).
The reservoir is filled with fluid through the reservoir filling system (Ref. 29-16-00).
B. Electric Pump 2075GJ
Electric Pump 2075GJ
Electric Pump 2075GJ ** ON A/C NOT FOR ALL
Electric Pump 2075GJ ** ON A/C NOT FOR ALL
The electric pump 2075GJ is installed in the Blue hydraulic compartment. It supplies the Blue hydraulic system with hydraulic power. The electric pump has three main parts:
The electric motor is a conventional induction motor. It operates with a three-phase supply of electrical power. The motor turns at 7600 revolutions per minute (RPM) when it is under load. A shaft goes through the motor which has a blower attached to one end. The blower makes air flow through the motor to keep it cool. The hot air goes out of the aircraft through a flexible hose. Some hydraulic fluid is made to flow through the shaft to keep the main bearings and rotor cool.
The boost pump is connected to the other end of the shaft of the motor. The boost pump is of the impeller type. It increases the pressure of the fluid before it goes into the hydraulic pump. This makes the hydraulic pump more efficient. The boost pump increases the pressure of the fluid by 2.1 bar (30 psi). The shaft of the boost pump is connected to the hydraulic pump.
The hydraulic pump is attached to the boost pump. It is of the variable-displacement, in-line type. The pump has seven pistons, each of which has a maximum displacement of 4.3 ml/rev (0.25 cu.in./rev). A moveable yoke controls the displacement of the pistons. A spool valve compensator controls the yoke and thus the displacement of the pump. Thus the output of the pump is made to be the same as the amount of fluid the system needs.
The performance of the electric pump assembly is as follows:
Electric Pump 2075GJ Electric Pump 2075GJ ** ON A/C NOT FOR ALL Electric Pump 2075GJ ** ON A/C NOT FOR ALL - an electric motor,
- a boost pump,
- the hydraulic pump.
The electric motor is a conventional induction motor. It operates with a three-phase supply of electrical power. The motor turns at 7600 revolutions per minute (RPM) when it is under load. A shaft goes through the motor which has a blower attached to one end. The blower makes air flow through the motor to keep it cool. The hot air goes out of the aircraft through a flexible hose. Some hydraulic fluid is made to flow through the shaft to keep the main bearings and rotor cool.
The boost pump is connected to the other end of the shaft of the motor. The boost pump is of the impeller type. It increases the pressure of the fluid before it goes into the hydraulic pump. This makes the hydraulic pump more efficient. The boost pump increases the pressure of the fluid by 2.1 bar (30 psi). The shaft of the boost pump is connected to the hydraulic pump.
The hydraulic pump is attached to the boost pump. It is of the variable-displacement, in-line type. The pump has seven pistons, each of which has a maximum displacement of 4.3 ml/rev (0.25 cu.in./rev). A moveable yoke controls the displacement of the pistons. A spool valve compensator controls the yoke and thus the displacement of the pump. Thus the output of the pump is made to be the same as the amount of fluid the system needs.
The performance of the electric pump assembly is as follows:
(1) Electric motor
- power supply: 115/200 V AC 400 Hz,
- current consumption (running): 45 A
- current consumption (start-up): 138 A
- speed (under load): 7600 RPM,
- speed (no load): 8000 RPM.
(2) Hydraulic pump
A temperature switch is installed in the electric motor. If the temperature of the motor increases to 162 deg. C (503 deg. F) the switch operates and sends signals to the overhead panel and ECAM.
- delivery pressure at zero flow: 206 +3 -0 bar (2987 +43 -0 psi),
- delivery pressure at maximum flow of 32 l/min (8.45 USgal/min): 150 bar (2175 psi).
A temperature switch is installed in the electric motor. If the temperature of the motor increases to 162 deg. C (503 deg. F) the switch operates and sends signals to the overhead panel and ECAM.
C. Current Transformer 2706GJ
The current transformer 2706GJ is installed in the avionics compartment. It operates together with the current unbalance detector 2707GJ to detect faults in the motor of the electric pump. It compares the flow of current in each of the three phases of the AC supply to the motor. If the current in one phase is different from the other two the unit sends a signal to the current unbalance detector.
It is possible to test the operation of the current transformer. The test is done together with the test of the current unbalance detector. The test is started with the test pushbutton on the current unbalance detector.
A 28 V DC supply of electrical power is necessary for operation of the unit.
The current transformer 2706GJ is installed in the avionics compartment. It operates together with the current unbalance detector 2707GJ to detect faults in the motor of the electric pump. It compares the flow of current in each of the three phases of the AC supply to the motor. If the current in one phase is different from the other two the unit sends a signal to the current unbalance detector.
It is possible to test the operation of the current transformer. The test is done together with the test of the current unbalance detector. The test is started with the test pushbutton on the current unbalance detector.
A 28 V DC supply of electrical power is necessary for operation of the unit.
D. Current Unbalance Detector 2707GJ
The current unbalance detector 2707GJ is installed in the avionics compartment. The unit is a box which contains the necessary electrical circuits and components. The electrical connectors, test P/B and indicator light are installed on the top surface of the unit. The current unbalance detector operates together with the current transformer 2706GJ to give protection if there is a fault in the electrical pump motor. A 28 V DC supply is necessary for the unit to operate.
When there is a fault, the detector gets a signal from the current transformer. It uses this signal to stop the supply of power to relay 2705GJ and thus stop the motor. The indicator light comes on to show that the unit has operated (and stopped the motor). A time delay is included in the circuits of the detector. It stops operation of the unit if the unit gets an input signal for only a short time.
When the unit has operated, it stays in that condition until it is set again. This happens automatically when the supply of power to the unit is stopped (through operation of P/B switch 2704GJ) and then started again (and there is no fault signal from the current transformer).
It is possible to test the operation of the unit with the test P/B. When the P/B is operated, a signal, which is the same as a fault, is put into the current transformer. The two units then operate in the same way as when there is a real fault. The indicator light comes on to show that the units have operated correctly. The current unbalance detector has to be set again after the test.
The current unbalance detector 2707GJ is installed in the avionics compartment. The unit is a box which contains the necessary electrical circuits and components. The electrical connectors, test P/B and indicator light are installed on the top surface of the unit. The current unbalance detector operates together with the current transformer 2706GJ to give protection if there is a fault in the electrical pump motor. A 28 V DC supply is necessary for the unit to operate.
When there is a fault, the detector gets a signal from the current transformer. It uses this signal to stop the supply of power to relay 2705GJ and thus stop the motor. The indicator light comes on to show that the unit has operated (and stopped the motor). A time delay is included in the circuits of the detector. It stops operation of the unit if the unit gets an input signal for only a short time.
When the unit has operated, it stays in that condition until it is set again. This happens automatically when the supply of power to the unit is stopped (through operation of P/B switch 2704GJ) and then started again (and there is no fault signal from the current transformer).
It is possible to test the operation of the unit with the test P/B. When the P/B is operated, a signal, which is the same as a fault, is put into the current transformer. The two units then operate in the same way as when there is a real fault. The indicator light comes on to show that the units have operated correctly. The current unbalance detector has to be set again after the test.
E. Pulsation Dampener 2092GM
The pulsation dampener 2092GM is installed in the outlet line from the electric pump. It removes the pulses of pressure of the HP flow from the pump. The pulsation dampener consists of an empty metal sphere, with inlet and outlet connections on opposite sides.
The pulsation dampener 2092GM is installed in the outlet line from the electric pump. It removes the pulses of pressure of the HP flow from the pump. The pulsation dampener consists of an empty metal sphere, with inlet and outlet connections on opposite sides.
F. HP Manifold
The HP manifold 2111GM is installed in the Blue hydraulic compartment. It is an aluminum alloy casting machined to make it possible to install different components on the manifold. Some of the hydraulic connections between the manifold and components are of the bobbin type (Ref. AMM D/O 29-00-00-00). Thus, replacement of components is possible with minimum effect on other components or pipes. The manifold is drilled to make the internal connections between the components.
Components installed on the HP manifold are:
The HP manifold 2111GM is installed in the Blue hydraulic compartment. It is an aluminum alloy casting machined to make it possible to install different components on the manifold. Some of the hydraulic connections between the manifold and components are of the bobbin type (Ref. AMM D/O 29-00-00-00). Thus, replacement of components is possible with minimum effect on other components or pipes. The manifold is drilled to make the internal connections between the components.
Components installed on the HP manifold are:
- a solenoid valve,
- the pressure relief valve 2063GM,
- the HP filter 2048GM,
- check valves,
- the sampling valve 2187GM,
- the pressure transmitter 2065GN (Ref. AMM D/O 29-32-00-00),
- the pressure switch 2151GN (Ref. AMM D/O 29-32-00-00),
- the pressure switch 10-CE-1 (Ref. AMM D/O 27-00-00-00),
- the priority valve 2064GM.
G. System Accumulator 2070GM
The system accumulator 2070GM is the same as the system accumulator 1070GM installed in the Green hydraulic system (Ref. AMM D/O 29-11-00-00).
The system accumulator 2070GM is the same as the system accumulator 1070GM installed in the Green hydraulic system (Ref. AMM D/O 29-11-00-00).
H. Nitrogen Pressure Gage 2072GM
The nitrogen pressure gage 2072GM is installed on the system accumulator 2070GM. It is the same as the nitrogen pressure gage 1072GM installed in the Green hydraulic system (Ref. AMM D/O 29-11-00-00).
The nitrogen pressure gage 2072GM is installed on the system accumulator 2070GM. It is the same as the nitrogen pressure gage 1072GM installed in the Green hydraulic system (Ref. AMM D/O 29-11-00-00).
I. HP filter 2048GM
The HP filter 2048GM is installed on the HP manifold 2011GM. It is the same as the HP filter 1048GM installed in the Green hydraulic system (Ref. AMM D/O 29-11-00-00).
The HP filter 2048GM is installed on the HP manifold 2011GM. It is the same as the HP filter 1048GM installed in the Green hydraulic system (Ref. AMM D/O 29-11-00-00).
J. Case Drain Filter 2084GM
The case drain filter 2084GM is installed in the Blue hydraulic compartment. It is functionally the same as the HP filter 1048GM installed in the Green hydraulic system (Ref. AMM D/O 29-11-00-00). The only differences are in its size and the configuration of the filter head.
The case drain filter 2084GM is installed in the Blue hydraulic compartment. It is functionally the same as the HP filter 1048GM installed in the Green hydraulic system (Ref. AMM D/O 29-11-00-00). The only differences are in its size and the configuration of the filter head.
K. LP Filter 2002GM
The LP filter 2002GM is installed in the left-hand belly fairing, aft of the main landing-gear compartment. It is functionally the same as the LP filter 1002GM installed in the Green hydraulic system (Ref. AMM D/O 29-11-00-00). The only differences are in its size and the configuration of the filter head.
The LP filter 2002GM is installed in the left-hand belly fairing, aft of the main landing-gear compartment. It is functionally the same as the LP filter 1002GM installed in the Green hydraulic system (Ref. AMM D/O 29-11-00-00). The only differences are in its size and the configuration of the filter head.
L. 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).
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).
M. 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).
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).
N. 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).
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).
O. Check Valves
There are two types of check valve in the system. They are of:
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).
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).
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. AMM D/O 29-22-00-00).
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. AMM D/O 29-30-00-00).
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. AMM D/O 29-19-00-00).
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. AMM D/O 29-22-00-00).
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. AMM D/O 29-30-00-00).
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. AMM D/O 29-19-00-00).