DOC AIRBUS | AMM A320FENGINE MASTER CONTROL - DESCRIPTION AND OPERATION
** ON A/C NOT FOR ALL
** ON A/C NOT FOR ALL
1. HP Fuel Shut OFF Valve Control
A. General
The HP fuel shut off valve control is fully electrical. It is performed from the engine panel in the cockpit as follows:
The HP fuel shut off valve control is fully electrical. It is performed from the engine panel in the cockpit as follows:
HP and LP Fuel Shut Off Valves - Power Supplies- opening of the HP fuel SOV:
This is controlled by the EEC : the EEC receives the commands from the MASTER control switch and ignition selector switch. - closure of the HP fuel SOV:
This is controlled directly from the MASTER control switch in OFF position (Ref. 73-20-00 and 80-00-00).
The MASTER control switches are part of the panel 115VU.
B. Valve Operation
The aircraft provides 28 Volt DC power to the EEC for operation of the engine HP fuel shut off valve latching torque motor.
Two coils of the latching torque motor are operated by the EEC (1 per channel). Each coil provides the ON and OFF function depending upon the current polarity sent from the EEC.
One additional coil is controlled by the hardwired fuel-off input from the cockpit. When the ENG MASTER control switch is set on OFF position, an automatic shut-off of the FMU closure valve-solenoid supply is achieved by a time-delay relay. This opening time relay enables the power supply to be shut off 2 minutes after the engine shutdown.
The EEC Unit receives a feedback position signal from the HP fuel shut off valve indicating whether the valve is in the closed or open position ; the EEC generates also a disagree signal for cockpit indication.
In case of loss of aircraft power supply, the HP fuel valve remains in the same position as before the failure.
A spurious EEC unit signal cannot open the fuel valve when commanded off by the MASTER lever.
When the HP fuel shut off valve is selected open a spurious transient voltage on the OFF coil will not cause the permanent closure of the HP fuel valve.
The cockpit commanded OFF coil has priority over EEC commanded coils.
The connector for the fuel shutoff solenoid is located on the fuel metering unit.
The aircraft provides 28 Volt DC power to the EEC for operation of the engine HP fuel shut off valve latching torque motor.
Two coils of the latching torque motor are operated by the EEC (1 per channel). Each coil provides the ON and OFF function depending upon the current polarity sent from the EEC.
One additional coil is controlled by the hardwired fuel-off input from the cockpit. When the ENG MASTER control switch is set on OFF position, an automatic shut-off of the FMU closure valve-solenoid supply is achieved by a time-delay relay. This opening time relay enables the power supply to be shut off 2 minutes after the engine shutdown.
The EEC Unit receives a feedback position signal from the HP fuel shut off valve indicating whether the valve is in the closed or open position ; the EEC generates also a disagree signal for cockpit indication.
In case of loss of aircraft power supply, the HP fuel valve remains in the same position as before the failure.
A spurious EEC unit signal cannot open the fuel valve when commanded off by the MASTER lever.
When the HP fuel shut off valve is selected open a spurious transient voltage on the OFF coil will not cause the permanent closure of the HP fuel valve.
The cockpit commanded OFF coil has priority over EEC commanded coils.
The connector for the fuel shutoff solenoid is located on the fuel metering unit.
2. LP Fuel Shut Off Valve Control
A. General
The function of the LP fuel shut-off valve is to control the fuel supply at engine-to-pylon interface.
The valve is located on the engine fuel supply system in the wing leading edge.
The function of the LP fuel shut-off valve is to control the fuel supply at engine-to-pylon interface.
The valve is located on the engine fuel supply system in the wing leading edge.
B. Valve Operation
The LP fuel shut off valve is controlled:
The LP fuel shut off valve is controlled:
- From the cockpit overhead panel 20VU by means of the ENG FIRE pushbutton switch
- From the cockpit center pedestal 115VU by means of the MASTER control switch on, the ENG panel.