DOC AIRBUS | AMM A320FENGINE STARTING SYSTEM - DESCRIPTION AND OPERATION
** ON A/C NOT FOR ALL
** ON A/C NOT FOR ALL
1. Starter
A. General
The starter is attached to the forward face of the gearbox using a cast aluminium adapter and Quick-Attach-Detach (QAD) clamp. It is designed to rotate and accelerate the HP rotor of the engine to allow the starting.
The physical and operational characteristics of the starter are listed in table 001.
The starter is attached to the forward face of the gearbox using a cast aluminium adapter and Quick-Attach-Detach (QAD) clamp. It is designed to rotate and accelerate the HP rotor of the engine to allow the starting.
The physical and operational characteristics of the starter are listed in table 001.
B. Description
The starter consists of a drive turbine assembly housed in a steel/ containment housing (2), a gear reduction system, a clutch (8), output shaft assembly (7), a mounting adapter (5), Quick Attach Detach (QAD) clamp (10).
A steel inlet housing provides the starter air inlet flange and provides containment for the turbine rotor (15). Steel nozzles (1) which direct air into the rotor, are integral with the turbine inlet housing. Flow paths are shaped to minimise inlet and outlet losses.
The drive turbine rotative assembly consists of the rotor, shaft, pinion gear (11) and bearing cartridge. The turbine blades, hub, and shaft are integral and machined from a titanium forging. The shaft is supported by the bearing cartridge which utilises two preloaded angular contact ball bearings. A carbon seal assembly (6) is used to prevent external oil leakage from the rotor/bearing system.
A two-stage, triple-mesh train (3) transmits torque from the turbine to the output shaft (7). The gears are mounted in a magnesium gear cage which also supports the turbine rotor bearings. The turbine inlet housing and gear cage are bolted to the magnesium transmission housing which supports the clutch (9) and output shaft assembly (7).
The starter consists of a drive turbine assembly housed in a steel/ containment housing (2), a gear reduction system, a clutch (8), output shaft assembly (7), a mounting adapter (5), Quick Attach Detach (QAD) clamp (10).
Pneumatic StarterA steel inlet housing provides the starter air inlet flange and provides containment for the turbine rotor (15). Steel nozzles (1) which direct air into the rotor, are integral with the turbine inlet housing. Flow paths are shaped to minimise inlet and outlet losses.
The drive turbine rotative assembly consists of the rotor, shaft, pinion gear (11) and bearing cartridge. The turbine blades, hub, and shaft are integral and machined from a titanium forging. The shaft is supported by the bearing cartridge which utilises two preloaded angular contact ball bearings. A carbon seal assembly (6) is used to prevent external oil leakage from the rotor/bearing system.
A two-stage, triple-mesh train (3) transmits torque from the turbine to the output shaft (7). The gears are mounted in a magnesium gear cage which also supports the turbine rotor bearings. The turbine inlet housing and gear cage are bolted to the magnesium transmission housing which supports the clutch (9) and output shaft assembly (7).
C. Operation
(1) The starter is supplied with compressed air which rotates the turbine blades and is released through the air exhaust. The air is supplied through the pneumatic starter valve, the solenoid of which is controlled by the Engine Electronic Control (EEC). High speed and low torque is caused as the turbine rotates. This is changed into low speed, high torque by the reduction gear train. A clutch transmits torque from this gear hub to the output shaft through a ratchet and pawl mechanism.
(2) At starter speed between 5900 to 6120 rpm an electrical signal is transmitted from the engine tachometer. This signal removes electrical power from the starter solenoid and closes the pneumatic starter valve. The starter air supply stops and the starter speed decreases in relation to the engine speed. Centrifugal force overcomes the clutch leaf spring tension and releases the clutch pawls from the gear hub ratchet teeth. The starter turbine output shaft disengages and decreases its speed while the engine accelerates to operate at minimum power.
D. Lubrication
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| Physical and Operational Characteristics |
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| Turbine type :single stage axial flow |
| Reduction gearing : compound planetary |
| Internal engagement : pawl and ratchet type |
| Drive shaft disengagement speed : 5900 RPM to 6120 RPM |
| Drive shaft reengagement speed : 1412 RPM |
| Direction of output shaft rotation : clockwise when looking at mounting face |
| of starter |
| LUBRICATION |
| System type : splash type system |
| Capacity : 12 FL.OZ (approximately 360 cc) |
E. Containment
In the event of a starter turbine overspeed (due to starter valve failed open or the clutch failed engaged), the rim and blade will separate from the hub at a predetermined rotational speed value.
The steel inlet housing is designed to contain all fragments within its own envelope, except for fragments emitted from the exhaust.
Any fragments emitted from the exhaust will not have sufficient energy to provoque powerplant or aircraft secondary damage.
The starter will remain on its mounting pad and the inlet duct will not shear off during a burst situation.
In the event of a starter turbine overspeed (due to starter valve failed open or the clutch failed engaged), the rim and blade will separate from the hub at a predetermined rotational speed value.
The steel inlet housing is designed to contain all fragments within its own envelope, except for fragments emitted from the exhaust.
Any fragments emitted from the exhaust will not have sufficient energy to provoque powerplant or aircraft secondary damage.
The starter will remain on its mounting pad and the inlet duct will not shear off during a burst situation.
2. Pneumatic Starter Valve
A. General
The pneumatic starter valve is installed on the air duct on the lower right side of the LP compressor. It is provided to control the supply of the starter with air, from an order given by the EEC.
The pneumatic starter valve is installed on the air duct on the lower right side of the LP compressor. It is provided to control the supply of the starter with air, from an order given by the EEC.
B. Description
(1) The starter valve is a butterfly type valve, pneumatically operated and electrically controlled. The valve is installed on the air duct on the lower right hand side of the LP compressor case.
(2) The starter valve controls the flow of air from the air duct to the engine starter.
(3) The steel butterfly valve is installed on a stainless steel shaft, which is held in PTFE bushes.
(4) An extension on the valve shaft can be used to manually operate the valve. This can be done with a 0.375 in. square socket. The extension includes a switch and a visual position indication device. As the valve opens more than 7 degrees, the switch operates and transmits a position indication to the EEC.
(5) Pneumatic control is given by a two-function diaphragm type actuator and a solenoid valve. The actuator has two pistons of different areas which are installed on the same shaft. Actuator movement is linked mechanically to the butterfly valve shaft.
(6) The solenoid valve has an electrically operated solenoid, a ball valve and a plunger loaded by a spring.
C. Operation
(1) To open the valve:
Air from immediately upstream of the butterfly valve is put through a filter. The filtered air is then passed through an orifice and supplied to the solenoid valve. Air from upstream of the orifice is also supplied to the smaller piston of the two-function actuator. When the solenoid is energized, its ball valve opens, which permits the flow of air to the larger piston. The movement of this ball valve also simultaneously closes the bleed to ambient. The air then pushes against the face of the larger piston on the two-function actuator.
The piston moves to the left as its pressure increases above that of both the spring and the small-area piston. Actuator movement is transmitted through its linkage and turns the butterfly valve to the open position.
Air from immediately upstream of the butterfly valve is put through a filter. The filtered air is then passed through an orifice and supplied to the solenoid valve. Air from upstream of the orifice is also supplied to the smaller piston of the two-function actuator. When the solenoid is energized, its ball valve opens, which permits the flow of air to the larger piston. The movement of this ball valve also simultaneously closes the bleed to ambient. The air then pushes against the face of the larger piston on the two-function actuator.
The piston moves to the left as its pressure increases above that of both the spring and the small-area piston. Actuator movement is transmitted through its linkage and turns the butterfly valve to the open position.
(2) To close the valve:
When electrical power is removed from the solenoid valve, the ball valve closes. Air pressure from the larger piston of the two-function actuator is bled to ambient through the solenoid valve. The air pressure from the smaller piston closes the two-function actuator and through its linkage, closes the butterfly valve. The actuator spring will also close the butterfly valve if there is a pressure drop upstream of the butterfly valve. The valve will stay closed until air pressure is supplied and the solenoid is operated again.
When electrical power is removed from the solenoid valve, the ball valve closes. Air pressure from the larger piston of the two-function actuator is bled to ambient through the solenoid valve. The air pressure from the smaller piston closes the two-function actuator and through its linkage, closes the butterfly valve. The actuator spring will also close the butterfly valve if there is a pressure drop upstream of the butterfly valve. The valve will stay closed until air pressure is supplied and the solenoid is operated again.
(3) Manual operation
If an electrical failure occurs in the starter valve, the butterfly valve can be operated manually. An extension is included at the actuator end of the butterfly shaft, which is used to manually operate the valve. The end of the shaft is adapted to engage a 0.375 in. square drive.
If an electrical failure occurs in the starter valve, the butterfly valve can be operated manually. An extension is included at the actuator end of the butterfly shaft, which is used to manually operate the valve. The end of the shaft is adapted to engage a 0.375 in. square drive.
(4) Position indication
The position of the butterfly valve is indicated through a plunger operated switch.
The position of the butterfly valve is indicated through a plunger operated switch.
(5) Pneumatic starter valve test
The operation of the pneumatic starter valve can be checked on ground, engine not running, through the maintenance MENU mode of the EEC.
This test will be performed by selecting the STARTER VALVE TEST page in the MENU.
The operation of the pneumatic starter valve can be checked on ground, engine not running, through the maintenance MENU mode of the EEC.
This test will be performed by selecting the STARTER VALVE TEST page in the MENU.