DOC AIRBUS | AMM A320FCARGO COMPARTMENT DOOR HYDRAULIC SYSTEM - DESCRIPTION AND OPERATION
** ON A/C NOT FOR ALL
1. General
The hydraulic system of the cargo compartment doors (referred to as door hydraulic system) controls the operation of the FWD and AFT cargo compartment doors (referred to as cargo door). The system includes the duplex door actuators (two for each cargo door), two manual selector valves (one for each cargo door) and one electro-manual selector.
The system gets its hydraulic supply from the Yellow hydraulic system.
** ON A/C NOT FOR ALL The hydraulic system of the cargo compartment doors (referred to as door hydraulic system) controls the operation of the FWD and AFT cargo compartment doors (referred to as cargo door). The system includes the duplex door actuators (two for each cargo door), two manual selector valves (one for each cargo door) and one electro-manual selector.
The system gets its hydraulic supply from the Yellow hydraulic system.
2. Component Location
Door Hydraulic System - Component Location at the Yellow Ground Service Panel ** ON A/C NOT FOR ALL
Door Hydraulic System - Component Location at the Yellow Ground Service Panel ** ON A/C NOT FOR ALL
Door Hydraulic System - Component Location at the Yellow Ground Service Panel ** ON A/C NOT FOR ALL
** ON A/C NOT FOR ALL Door Hydraulic System - Component Location at the Yellow Ground Service Panel ** ON A/C NOT FOR ALL Door Hydraulic System - Component Location at the Yellow Ground Service Panel ** ON A/C NOT FOR ALL Door Hydraulic System - Component Location at the Yellow Ground Service Panel ** ON A/C NOT FOR ALL | FIN | FUNCTIONAL DESIGNATION | PANEL | ZONE | ACCESS DOOR | ATA REF |
|---|---|---|---|---|---|
| ** ON A/C ALL | |||||
| 2502MJ | ACTUATOR-FWD CARGO DOOR, FWD | 132 | 52-36-18 | ||
| 2503MJ | ACTUATOR-FWD CARGO DOOR, AFT | 132 | 52-36-18 | ||
| 2504MJ | MAN SEL VALVE-AFT CARGO DOOR | 154AR | 152 | 52-36-15 | |
| 2505MJ | ACTUATOR-AFT CARGO DOOR, FWD | 152 | 52-36-18 | ||
| 2506MJ | ACTUATOR-AFT CARGO DOOR, AFT | 152 | 52-36-18 | ||
| 3009GM | CARGO DOOR HAND PUMP | 198CB | 198 | 52-36-11 | |
| 3188GM | CHECK VALVE Y | 198 | 27-20-00 | ||
| 3717GM | VALVE-DOUBLE CHECK | 252 | 52-36-13 | ||
3. System Description
The door hydraulic system supplies the duplex door actuators with hydraulic power. The door actuators extend to open the cargo doors to the outer side. It is possible to open the FWD and AFT cargo door at the same time.
The electric pump of the Yellow hydraulic system supplies the door hydraulic system with hydraulic power. If this hydraulic power is not available, it is possible to pressurize the door hydraulic system with the hand pump. The normal system pressure of the door hydraulic system is 3000 psi (206 bar).
The electrical control system of the cargo doors supplies the hydraulic components with electrical power. It prevents the operation of the door hydraulic system when the cargo doors are locked.
The restrictors of the door actuators and the manual selector valves control the speed of the cargo doors.
** ON A/C NOT FOR ALL The door hydraulic system supplies the duplex door actuators with hydraulic power. The door actuators extend to open the cargo doors to the outer side. It is possible to open the FWD and AFT cargo door at the same time.
The electric pump of the Yellow hydraulic system supplies the door hydraulic system with hydraulic power. If this hydraulic power is not available, it is possible to pressurize the door hydraulic system with the hand pump. The normal system pressure of the door hydraulic system is 3000 psi (206 bar).
The electrical control system of the cargo doors supplies the hydraulic components with electrical power. It prevents the operation of the door hydraulic system when the cargo doors are locked.
The restrictors of the door actuators and the manual selector valves control the speed of the cargo doors.
4. Component Description
Door Hydraulic System - Component Location at the Yellow Ground Service Panel ** ON A/C NOT FOR ALL
Door Hydraulic System - Component Location at the Yellow Ground Service Panel ** ON A/C NOT FOR ALL
Door Hydraulic System - Component Location at the Yellow Ground Service Panel ** ON A/C NOT FOR ALL
The manual selector valve 2501MJ (2504MJ) is installed behind the control panel and controls the operation of the cargo door. This valve has an extension mode, a neutral mode, an interim mode and a retraction mode.
The extension mode makes sure that the high-pressure (HP) fluid can flow through the valve to extend the door actuators. In the neutral mode, the HP fluid cannot flow through the valve. For safety, the interim mode pressurizes first the extension sides (port A) of the door actuators. This prevents a sudden movement of the cargo door to a lower position when it starts to close. When the pressure is sufficient, the valve can move in the retraction mode. The HP fluid can then flow through the valve to pressurize the door actuators on the retraction sides (port B).
The electrical selector valve 2500MJ is installed on the Yellow ground service panel of the aft, right belly fairing. The valve housing includes:
When the solenoid is energized, it moves the control valve in position which lets the HP fluid operate the main valve. The pressure puts the main valve in position and the HP fluid can flow to pressurize the door hydraulic system (normal and/or manual mode).
The leakage restrictor lets residual system pressure drain into the return line.
The door actuators 2502MJ and 2503MJ (2505MJ and 2506MJ) are installed at FR26A (FR54A) and FR25A (FR53A). They are attached between the actuator attachment fitting on the door structure and the actuator beam of the fuselage structure.
Usually, the door actuators 2502MJ and 2503MJ (2505MJ and 2506MJ) extend in parallel and divide the total load of the cargo door. If one door actuator fails, the other is sufficient to operate the cargo door with the same performance.
Extension of the Door Actuator:
When HP fluid flows through the port A of the door actuator, the piston of the door actuator extends. When the piston is fully extended, the pawls on the piston end move around an internal lock. The pawls then press the locking piston against the spring of the locking cylinder.
When the hydraulic pressure to the port A is shut off, the spring pressure operates the locking piston. The locking piston moves a small distance against the pawls and presses them against the internal lock. Thus, the door actuator is mechanically locked in its extended position.
While the door actuator is locked, the pawls operate the target of the proximity switch with a lever. The proximity switch sends a signal to the indicator light 9MJ (8MJ) on the control panel.
Retraction of the Door Actuator:
When the HP fluid flows through the port B of the door actuator, the piston of the door actuator retracts. When the door actuator is in the extended locked position, the HP fluid operates the locking piston against the spring. The pawls come free from the internal lock and release the mechanical lock. At the same time, the target of the proximity switch moves back. The door actuator is no longer mechanically locked and the piston of the door actuator retracts.
The handpump 3009GM is installed on the Yellow ground service panel of the right, aft belly fairing. The operation of the handpump pressurizes the door hydraulic system. A pressure relief valve, installed on the pressure outlet of the handpump, prevents too high a pressure during the manual operation.
The double check valve 3717GM, which includes a normal and a bypass check valve, is installed in the supply line of the door hydraulic system.
The normal check valve opens the supply line when the system pressure increases to 5.5 bar. It also prevents a loss of hydraulic fluid during flight if a leakage in the supply line occurs.
The bypass check valve makes sure that the supply line is depressurized after each hydraulic operation of the cargo door.
The check valve 3188GM is installed in the return line of the door hydraulic system. It protects the door hydraulic system against a pressurization of the low-pressure system.
** ON A/C NOT FOR ALL Door Hydraulic System - Component Location at the Yellow Ground Service Panel ** ON A/C NOT FOR ALL Door Hydraulic System - Component Location at the Yellow Ground Service Panel ** ON A/C NOT FOR ALL Door Hydraulic System - Component Location at the Yellow Ground Service Panel ** ON A/C NOT FOR ALL NOTE: The identification numbers in brackets are for the components of the AFT cargo door.
To operate the FWD (AFT) cargo door, a control panel is installed on the fuselage. To get access to the control panel, open the access panel 134AR (154AR). On the control panel there is a selector to operate the manual selector valve 2501MJ (2504MJ) and a green indicator light 9MJ (8MJ). The indicator light comes on when the door actuators 2502MJ and 2503MJ (2505MJ and 2506MJ) are in their extended, locked positions. The selector is spring-loaded to the neutral position. When you release it in the "Open" or "Closed" position, it moves back to the neutral position. The manual selector valve 2501MJ (2504MJ) is installed behind the control panel and controls the operation of the cargo door. This valve has an extension mode, a neutral mode, an interim mode and a retraction mode.
The extension mode makes sure that the high-pressure (HP) fluid can flow through the valve to extend the door actuators. In the neutral mode, the HP fluid cannot flow through the valve. For safety, the interim mode pressurizes first the extension sides (port A) of the door actuators. This prevents a sudden movement of the cargo door to a lower position when it starts to close. When the pressure is sufficient, the valve can move in the retraction mode. The HP fluid can then flow through the valve to pressurize the door actuators on the retraction sides (port B).
The electrical selector valve 2500MJ is installed on the Yellow ground service panel of the aft, right belly fairing. The valve housing includes:
- a solenoid-operated control valve
- a hydraulically operated main valve
- a leakage restrictor.
When the solenoid is energized, it moves the control valve in position which lets the HP fluid operate the main valve. The pressure puts the main valve in position and the HP fluid can flow to pressurize the door hydraulic system (normal and/or manual mode).
The leakage restrictor lets residual system pressure drain into the return line.
The door actuators 2502MJ and 2503MJ (2505MJ and 2506MJ) are installed at FR26A (FR54A) and FR25A (FR53A). They are attached between the actuator attachment fitting on the door structure and the actuator beam of the fuselage structure.
Usually, the door actuators 2502MJ and 2503MJ (2505MJ and 2506MJ) extend in parallel and divide the total load of the cargo door. If one door actuator fails, the other is sufficient to operate the cargo door with the same performance.
Extension of the Door Actuator:
When HP fluid flows through the port A of the door actuator, the piston of the door actuator extends. When the piston is fully extended, the pawls on the piston end move around an internal lock. The pawls then press the locking piston against the spring of the locking cylinder.
When the hydraulic pressure to the port A is shut off, the spring pressure operates the locking piston. The locking piston moves a small distance against the pawls and presses them against the internal lock. Thus, the door actuator is mechanically locked in its extended position.
While the door actuator is locked, the pawls operate the target of the proximity switch with a lever. The proximity switch sends a signal to the indicator light 9MJ (8MJ) on the control panel.
Retraction of the Door Actuator:
When the HP fluid flows through the port B of the door actuator, the piston of the door actuator retracts. When the door actuator is in the extended locked position, the HP fluid operates the locking piston against the spring. The pawls come free from the internal lock and release the mechanical lock. At the same time, the target of the proximity switch moves back. The door actuator is no longer mechanically locked and the piston of the door actuator retracts.
The handpump 3009GM is installed on the Yellow ground service panel of the right, aft belly fairing. The operation of the handpump pressurizes the door hydraulic system. A pressure relief valve, installed on the pressure outlet of the handpump, prevents too high a pressure during the manual operation.
The double check valve 3717GM, which includes a normal and a bypass check valve, is installed in the supply line of the door hydraulic system.
The normal check valve opens the supply line when the system pressure increases to 5.5 bar. It also prevents a loss of hydraulic fluid during flight if a leakage in the supply line occurs.
The bypass check valve makes sure that the supply line is depressurized after each hydraulic operation of the cargo door.
The check valve 3188GM is installed in the return line of the door hydraulic system. It protects the door hydraulic system against a pressurization of the low-pressure system.
5. Operation
NOTE: The identification numbers in brackets are for the components of the AFT cargo compartment door.
A. Normal Opening Procedure
To operate the door hydraulic system, make sure that the FWD (AFT) cargo door is in the "Unlocked" condition. The cargo door is unlocked when:
To get access to the control panel of door hydraulic system, open the access panel 134AR (154AR) below the fuselage.
To operate the door hydraulic system, set the selector on the control panel to the "Open" position and hold it. This moves the manual selector valve 2501MJ (2504MJ) to the extension mode and completes the circuit of the door control system. The electric pump 3075GX is energized and supplies the door hydraulic system with HP fluid. The fluid flows through the electro-manual selector valve 2500MJ and the manual selector valve 2501MJ (2504MJ) to the door actuators 2502MJ and 2503MJ (2505MJ and 2506MJ). The door actuators extend and open the cargo door to the outer side.
During this procedure, the selector on the control panel must stay in the "Open" position. When the selector is in the neutral position and the cargo door is not fully opened, then:
To operate the door hydraulic system, make sure that the FWD (AFT) cargo door is in the "Unlocked" condition. The cargo door is unlocked when:
- the door locking handle is out of its recess and
- the door locking handle is in the "Unlocked" position.
To get access to the control panel of door hydraulic system, open the access panel 134AR (154AR) below the fuselage.
To operate the door hydraulic system, set the selector on the control panel to the "Open" position and hold it. This moves the manual selector valve 2501MJ (2504MJ) to the extension mode and completes the circuit of the door control system. The electric pump 3075GX is energized and supplies the door hydraulic system with HP fluid. The fluid flows through the electro-manual selector valve 2500MJ and the manual selector valve 2501MJ (2504MJ) to the door actuators 2502MJ and 2503MJ (2505MJ and 2506MJ). The door actuators extend and open the cargo door to the outer side.
During this procedure, the selector on the control panel must stay in the "Open" position. When the selector is in the neutral position and the cargo door is not fully opened, then:
- the electrical circuit of door control system is interrupted
- the manual selector valve 2501MJ (2504MJ) is in the neutral mode
- the electrical pump 3075GX stops the hydraulic supply
- the cargo door stops and stays in this position.
B. Normal Closing Procedure
To close the cargo door hydraulically, make sure that the manual YZ-latches of the door sill latches are in the raised position. Then turn the selector on the control panel to the "Close" position.
This operation moves the manual selector valve 2501MJ (2504MJ) to the interim mode and completes the circuit of the door control system. Then the electric pump 3075GX starts and supplies the door hydraulic system with HP fluid. The fluid flows through the electro-manual selector valve 2500MJ and the manual selector valve 2501MJ (2504MJ) to the door actuators 2502MJ and 2503MJ (2505MJ and 2506MJ). The fluid pressurizes the door actuators on the extension side (port A).
When the pressure is sufficent, the selector on the control panel moves to the "Close" position. Then the manual selector valve 2501MJ (2504MJ) is in the retraction mode to pressurize the door actuator on the retraction side (port B). The HP fluid releases the mechanically locked door actuators 2502MJ and 2503MJ (2505MJ and 2506MJ) and retracts them. Then the FWD (AFT) cargo door closes and the green indicator light 9MJ (8MJ) on the control panel goes off.
During this procedure the selector on the control panel must remain in the "Close" position. When the selector is in the neutral position and the cargo door is not closed, then:
To close the FWD (AFT) cargo door completely, turn the selector again to the "Close" position and hold it. When the FWD (AFT) cargo door is fully closed, release the selector on the control panel.
Because of the internal leakage and the door weight it may occur that the cargo door opens again. To prevent this, lock the cargo door within a period of three seconds. The cargo door is correctly locked, when the door locking handle
At the same time, the safety mechanism operates the drift pin mechanism to extend the drift pins into their fuselage pockets. The door locking handle also operates the proximity switch 28WV (34WV) of the door warning system which stops the signal to the ECAM system. This cancels the visual warnings in the cockpit.
At the end of the normal closing procedure, make sure that the access panel 134AR (154AR) is closed.
To close the cargo door hydraulically, make sure that the manual YZ-latches of the door sill latches are in the raised position. Then turn the selector on the control panel to the "Close" position.
This operation moves the manual selector valve 2501MJ (2504MJ) to the interim mode and completes the circuit of the door control system. Then the electric pump 3075GX starts and supplies the door hydraulic system with HP fluid. The fluid flows through the electro-manual selector valve 2500MJ and the manual selector valve 2501MJ (2504MJ) to the door actuators 2502MJ and 2503MJ (2505MJ and 2506MJ). The fluid pressurizes the door actuators on the extension side (port A).
When the pressure is sufficent, the selector on the control panel moves to the "Close" position. Then the manual selector valve 2501MJ (2504MJ) is in the retraction mode to pressurize the door actuator on the retraction side (port B). The HP fluid releases the mechanically locked door actuators 2502MJ and 2503MJ (2505MJ and 2506MJ) and retracts them. Then the FWD (AFT) cargo door closes and the green indicator light 9MJ (8MJ) on the control panel goes off.
During this procedure the selector on the control panel must remain in the "Close" position. When the selector is in the neutral position and the cargo door is not closed, then:
- the electrical circuit of the door control system is interrupted,
- the manual selector valve 2501MJ (2504MJ) is in the neutral mode,
- the electric pump 3075GX stops the hydraulic supply,
- the cargo door stops and remains in this position.
To close the FWD (AFT) cargo door completely, turn the selector again to the "Close" position and hold it. When the FWD (AFT) cargo door is fully closed, release the selector on the control panel.
Because of the internal leakage and the door weight it may occur that the cargo door opens again. To prevent this, lock the cargo door within a period of three seconds. The cargo door is correctly locked, when the door locking handle
- is in the horizontal position and
- is pushed in the recess of the handle flap.
At the same time, the safety mechanism operates the drift pin mechanism to extend the drift pins into their fuselage pockets. The door locking handle also operates the proximity switch 28WV (34WV) of the door warning system which stops the signal to the ECAM system. This cancels the visual warnings in the cockpit.
At the end of the normal closing procedure, make sure that the access panel 134AR (154AR) is closed.
C. Manual Opening Procedure
The manual opening procedure of the FWD (AFT) cargo door is an alternative procedure which is used, when:
To release the cargo door, put the door locking handle in the "unlocked" position. The procedure is the same as for the normal opening procedure.
To operate the door hydraulic system manually, two persons are necessary:
The hydraulic fluid flows from the reservoir through the manual selector valve 2501MJ (2504MJ) to the door actuators 2502MJ and 2503MJ (2505MJ and 2506MJ). The door actuators extend and open the cargo door to the outer side.
When you stop to operate the hand pump 3009GM or when you release the selector, the cargo door stops. It then remains in position. To continue, set the selector to the "Open" position and operate the lever of the hand pump 3009GM again. Then the door actuators 2502MJ and 2503MJ (2505MJ and 2506MJ) extend again and the cargo door moves in the open direction. The force which is necessary to move the hand pump lever increases suddenly when the door actuators are in their extended, locked positions.
The manual opening procedure is complete when:
The manual opening procedure of the FWD (AFT) cargo door is an alternative procedure which is used, when:
- there is a failure in the electrical system,
- the electric pump fails.
NOTE: To simulate an electrical system or an electric pump failure, open, safety and tag the circuit breaker 1MJ on panel 122VU.
To release the cargo door, put the door locking handle in the "unlocked" position. The procedure is the same as for the normal opening procedure.
To operate the door hydraulic system manually, two persons are necessary:
- one must turn and hold the selector on the control panel to the "Open" position during the whole procedure. To get access to the control panel, open the access panel 134AR (154AR) beneath the fuselage.
- the other must operate the hand pump 3009GM on the Yellow ground service panel. To get access to this panel, open the access panel 198CB in the right, aft belly fairing area.
The hydraulic fluid flows from the reservoir through the manual selector valve 2501MJ (2504MJ) to the door actuators 2502MJ and 2503MJ (2505MJ and 2506MJ). The door actuators extend and open the cargo door to the outer side.
When you stop to operate the hand pump 3009GM or when you release the selector, the cargo door stops. It then remains in position. To continue, set the selector to the "Open" position and operate the lever of the hand pump 3009GM again. Then the door actuators 2502MJ and 2503MJ (2505MJ and 2506MJ) extend again and the cargo door moves in the open direction. The force which is necessary to move the hand pump lever increases suddenly when the door actuators are in their extended, locked positions.
The manual opening procedure is complete when:
- the selector on the control panel is released,
- the access panels 134AR (154AR) and 198CB are closed.
D. Manual Closing Procedure
The manual closing procedure of the cargo door is an alternative procedure which is used, when:
To operate the door hydraulic system manually two persons are necessary:
The fluid pressurizes the door actuators on the extension side (port A). When the pressure is sufficent, the selector on the control panel moves to the fully "Close" position. Then the manual selector valve 2501MJ (2504MJ) is in the retraction mode to pressurize the door actuator on the retraction side (port B). The HP fluid releases the mechanically locked door actuators 2502MJ and 2503MJ (2505MJ and 2506MJ). The door actuators retract and the cargo door moves in the close direction.
When you stop to operate the hand pump 3009GM or when you release the selector, the cargo door stops. It then remains in this position. To continue, turn the selector to the "Close" position and operate the lever of the hand pump 3009GM again. When the FWD (AFT) cargo door is flush with the fuselage contour, stop to operate the hand pump 3009GM and release the selector.
The manual closing procedure is complete when:
The manual closing procedure of the cargo door is an alternative procedure which is used, when:
- there is a failure in the electrical system,
- the electric pump fails.
NOTE: To simulate an electrical system or an electric pump failure, open, safety and tag the circuit breaker 1MJ on panel 122VU.
To operate the door hydraulic system manually two persons are necessary:
- one must turn the selector on the control panel to the "Close" position and hold it during the whole procedure. To get access to the control panels, open the access panel 134AR (154AR) beneath the fuselage.
- the other must operate the hand pump 3009GM on the Yellow ground service panel. To get access to this panel, open the access panel 198CB in the right, aft belly fairing area.
The fluid pressurizes the door actuators on the extension side (port A). When the pressure is sufficent, the selector on the control panel moves to the fully "Close" position. Then the manual selector valve 2501MJ (2504MJ) is in the retraction mode to pressurize the door actuator on the retraction side (port B). The HP fluid releases the mechanically locked door actuators 2502MJ and 2503MJ (2505MJ and 2506MJ). The door actuators retract and the cargo door moves in the close direction.
When you stop to operate the hand pump 3009GM or when you release the selector, the cargo door stops. It then remains in this position. To continue, turn the selector to the "Close" position and operate the lever of the hand pump 3009GM again. When the FWD (AFT) cargo door is flush with the fuselage contour, stop to operate the hand pump 3009GM and release the selector.
The manual closing procedure is complete when:
- the cargo door is in the "Locked" condition. This is the same as for the normal closing procedure,
- the access panels 134AR (154AR) and 198CB are closed.