DOC AIRBUS | AMM A320FAPU LP FUEL SHUT OFF - DESCRIPTION AND OPERATION
** ON A/C NOT FOR ALL
** ON A/C NOT FOR ALL
1. General
The APU Low Pressure (LP) fuel shutoff system has an APU fuel LP valve. The valve is used to isolate the APU fuel-supply line from the engine-feed line, when the APU does not operate. The valve also serves as a fire shut-off valve in case of APU fire. The APU fuel-supply line is routed through the pressurized fuselage. Three tanks, one in each wing and one in the wing center box in the fuselage are used to store the fuel.
** ON A/C NOT FOR ALL The APU Low Pressure (LP) fuel shutoff system has an APU fuel LP valve. The valve is used to isolate the APU fuel-supply line from the engine-feed line, when the APU does not operate. The valve also serves as a fire shut-off valve in case of APU fire. The APU fuel-supply line is routed through the pressurized fuselage. Three tanks, one in each wing and one in the wing center box in the fuselage are used to store the fuel.
2. Component Location
** ON A/C NOT FOR ALL | FIN | FUNCTIONAL DESIGNATION | PANEL | ZONE | ACCESS DOOR | ATA REF |
|---|---|---|---|---|---|
| ** ON A/C ALL | |||||
| 3QF | ACTUATOR-APU FUEL LP VALVE | 141 | 28-29-51 | ||
| 14QM | VALVE-APU FUEL LP | 141 | 28-29-41 | ||
3. System Description
The APU LP fuel shutoff system has a fuel LP valve 14QM, an adaptor 5020QM and a related fuel LP valve actuator 3QF. The actuator is installed on the adaptor 5020QM. The valve and the adaptor are installed on the rear spar of the wing center-box. The valve 14QM is installed in the APU fuel-supply line, where it joins the adjacent engine-feed line. The valve isolates the APU fuel-supply line from the engine fuel-feed line. The electrical circuit of the valve is linked to these circuits which control the valve operation:
** ON A/C NOT FOR ALL The APU LP fuel shutoff system has a fuel LP valve 14QM, an adaptor 5020QM and a related fuel LP valve actuator 3QF. The actuator is installed on the adaptor 5020QM. The valve and the adaptor are installed on the rear spar of the wing center-box. The valve 14QM is installed in the APU fuel-supply line, where it joins the adjacent engine-feed line. The valve isolates the APU fuel-supply line from the engine fuel-feed line. The electrical circuit of the valve is linked to these circuits which control the valve operation:
- APU fuel pump circuit (Ref. AMM D/O 28-22-00-00),
- APU emergency shutdown circuit (Ref. AMM D/O 49-62-00-00),
- APU engine fuel and control circuit (Ref. AMM D/O 49-30-00-00),
- APU fire extinguishing circuit (Ref. AMM D/O 26-22-00-00).
4. Power Supply
The two DC motors in the actuator 3QF, which move the valve 14QM, are supplied from different sources. One motor is supplied with 28VDC from the normal busbar 301PP. The other motor is supplied with 28VDC from the hot bat. busbar 701PP.
** ON A/C NOT FOR ALL The two DC motors in the actuator 3QF, which move the valve 14QM, are supplied from different sources. One motor is supplied with 28VDC from the normal busbar 301PP. The other motor is supplied with 28VDC from the hot bat. busbar 701PP.
5. Interfaces
The APU LP fuel shutoff system has interfaces with:
** ON A/C NOT FOR ALL The APU LP fuel shutoff system has interfaces with:
- APU fuel-pump system (Ref. AMM D/O 28-22-00-00),
- APU emergency-shutdown system (Ref. AMM D/O 49-62-00-00),
- APU fire-extinguishing system (Ref. AMM D/O 26-22-00-00),
- APU fuel distribution system (Ref. AMM D/O 49-31-00-00),
- Electronic Centralized Aircraft Monitoring (ECAM) system (Ref. AMM D/O 31-51-00-00).
A. Description of the APU Fuel LP Valve FIN: 14-QM
(1) The APU fuel LP valve has a ball valve assembly (14QM) and an actuator assembly (3QF). You can remove the actuator, with the valve in position, without the necessity to drain the system. The ball valve assembly (14QM) is attached with four bolts in self-locking inserts to the rear spar of the wing center-box. Four studs in the valve, which come through holes in the rear spar, are used to attach the actuator (3QF). The valve is a body with pipeline attachments. The fuel inlet connector is a threaded-type connection. The fuel outlet-port has four studs for installation of the fuel outlet tube. The valve body includes a ball with 0.5 in. (12.7 mm) dia. bore and a drive-shaft for the includes a ball with 0.5 in. (12.7 mm) dia. bore and a drive-shaft for the Polytetrafluorethylene (PTFE) valve seat. An integrated spring loaded poppet-valve allows thermal pressure relief in the opposite direction to normal flow when the valve is closed. The drive slot on top of the ball lets the ball move in direct relation to the drive shaft.
B. Description of the Actuator Assembly
(1) The actuator assembly (3QF) has two electrical DC motors which drive together. The two motors drive a common planetary gear system, with the drive-shaft through clutches, to operate the valve. The gear system permits one motor to drive the valve if the other motor does not operate. Two groups of three microswitches activate the related 'OPEN' or 'CLOSED' circuit for operation of the valve. They are located at the bottom of the actuator. The microswitches are operated with levers, which are tipped with a cam on the actuator drive-shaft. A window in the actuator body gives a visual indication of the valve, RED for 'OPEN' or GREEN for 'CLOSED' position.
7. Operation/Control and Indicating
ECAM Location and Typical Displays ** ON A/C NOT FOR ALL
ECAM Location and Typical Displays ** ON A/C NOT FOR ALL
ECAM Location and Typical Displays ** ON A/C NOT FOR ALL
ECAM Location and Typical Displays ** ON A/C NOT FOR ALL ECAM Location and Typical Displays ** ON A/C NOT FOR ALL ECAM Location and Typical Displays ** ON A/C NOT FOR ALL A. Normal Operation
(1) The APU Fuel Supply
When the APU MASTER SW is set to on, the ECB energizes the APU MAIN RELAY 4KD. It energizes the APU fuel LP valve-actuator 3QF and the APU fuel LP valve 14QM opens. Then the engine pump or APU fuel pump supply the necessary fuel from the engine feed line to the APU fuel distribution system.
When the APU MASTER SW is set to on, the ECB energizes the APU MAIN RELAY 4KD. It energizes the APU fuel LP valve-actuator 3QF and the APU fuel LP valve 14QM opens. Then the engine pump or APU fuel pump supply the necessary fuel from the engine feed line to the APU fuel distribution system.
(2) APU Shutdown
When the APU shuts down, the ECB de-energizes the APU MAIN RELAY 4KD. It de-energizes the APU fuel LP valve-actuator 3QF and the APU fuel LP valve 14QM closes. The APU MAIN RELAY 4KD de-energizes the APU fuel feed pump 4QC if it was in operation.
When the APU shuts down, the ECB de-energizes the APU MAIN RELAY 4KD. It de-energizes the APU fuel LP valve-actuator 3QF and the APU fuel LP valve 14QM closes. The APU MAIN RELAY 4KD de-energizes the APU fuel feed pump 4QC if it was in operation.
(3) APU Fuel-Feed Pump Operation for Ground Maintenance
The vent APU fuel line pushbutton switch 8QC permits the APU fuel-feed pump 4QC to operate on the ground (to purge the APU fuel-feed line during ground maintenance).
When you operate the VENT APU FUEL LINE pushbutton switch 8QC:
The vent APU fuel line pushbutton switch 8QC permits the APU fuel-feed pump 4QC to operate on the ground (to purge the APU fuel-feed line during ground maintenance).
When you operate the VENT APU FUEL LINE pushbutton switch 8QC:
- the APU fuel line vent relay 6QC energizes,
- the actuator fuel LP valve 3QF energizes and opens the APU fuel LP valve 14QM,
- the ESSENTIAL AC BUS 1 401XP supplies 115VAC single-phase to operate the motor of the APU fuel-feed pump 4QC.
B. Operation with Failures
(1) APU Emergency Shutdown
In an emergency APU shutdown, the actuator fuel LP valve 3QF automatically closes the APU fuel LP valve 14QM when:
Operation of any of these systems causes the FIRE EMERG STOP relays 5WF and 6WF to energize. The relay 5WF transmits a signal to the ECB 59KD thus the APU fuel LP valve 14QM closes and the APU fuel-feed pump 4QC stops.
The ECB 59KD transmits a signal to the ECAM which shows:
APU EMERG SHUTDOWN
MASTER SW ................OFF
In an emergency APU shutdown, the actuator fuel LP valve 3QF automatically closes the APU fuel LP valve 14QM when:
- the APU FIRE push switch (guarded red) in the module 1WD on panel 20VU on the overhead panel is operated,
- the APU SHUT OFF push switch 1KL (guarded red) on panel 108VU, forward of the nose landing-gear bay is operated,
- the fire detection system operates (on the ground only).
Operation of any of these systems causes the FIRE EMERG STOP relays 5WF and 6WF to energize. The relay 5WF transmits a signal to the ECB 59KD thus the APU fuel LP valve 14QM closes and the APU fuel-feed pump 4QC stops.
The ECB 59KD transmits a signal to the ECAM which shows:
APU EMERG SHUTDOWN
MASTER SW ................OFF
C. Indication
A 'closed' and an 'open' position microswitch, which are part of the actuator, transmit position signals to the SDAC (Ref. AMM D/O 31-54-00-00).
The SDAC transmits the signals to the Electronic Centralized Aircraft Monitoring (ECAM) system. You can see the 'OPEN', 'MOVING' or 'CLOSED' position of the valve on the fuel system page on the ECAM lower display unit (Ref. 31-51-00).
You can also see the valve position at the visual positon indicator on the actuator itself.
A 'closed' and an 'open' position microswitch, which are part of the actuator, transmit position signals to the SDAC (Ref. AMM D/O 31-54-00-00).
The SDAC transmits the signals to the Electronic Centralized Aircraft Monitoring (ECAM) system. The valve position is shown on the fuel system page on the ECAM lower display unit (Ref. AMM D/O 31-51-00-00).
A 'closed' and an 'open' position microswitch, which are part of the actuator, transmit position signals to the SDAC (Ref. AMM D/O 31-54-00-00).
The SDAC transmits the signals to the Electronic Centralized Aircraft Monitoring (ECAM) system. You can see the 'OPEN', 'MOVING' or 'CLOSED' position of the valve on the fuel system page on the ECAM lower display unit (Ref. 31-51-00).
You can also see the valve position at the visual positon indicator on the actuator itself.
A 'closed' and an 'open' position microswitch, which are part of the actuator, transmit position signals to the SDAC (Ref. AMM D/O 31-54-00-00).
The SDAC transmits the signals to the Electronic Centralized Aircraft Monitoring (ECAM) system. The valve position is shown on the fuel system page on the ECAM lower display unit (Ref. AMM D/O 31-51-00-00).
- Valve closed: white triangle
- Valve open: green triangle
- Valve move or emergency operation: amber triangle
You can also see the valve position at the visual positon indicator on the actuator itself.