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EFFECTIVITY
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ALL CFM56-5B ENGINES FOR A319-A320-A321
ENGINE SYSTEMS Jan 03
CFMI PROPRIETARY INFORMATION
CFM56-5B TRAINING MANUAL
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STARTER AIR VALVE
Closing operation.
The butterfly valve remains closed when the solenoid is de-energized.
Inlet air pressure is routed through a downstream facing probe and regulating orifice to chamber A. The probe prevents contaminants entering the valve.
The pressure is then routed across the solenoid pilot valve, now in the open position, to chamber B.
Since the pressure on both sides of diaphragm B is equal, no force remains. The pressure in chamber A exerts a force on diaphragm A, and this force, combined with the force of the closing torsion spring, closes the butterfly valve.
To prevent the possibility of valve malfunction due to freezing of the solenoid pilot valve, the unit incorporates a small permanent pneumatic bleed flow to heat the solenoid control valve.
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EFFECTIVITY
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ALL CFM56-5B ENGINES FOR A319-A320-A321
ENGINE SYSTEMS Jan 03
CFMI PROPRIETARY INFORMATION
CFM56-5B TRAINING MANUAL
EFG
STARTER AIR VALVE
Manual override operation.
The valve is manually opened by first pushing the wrench button and then, rotating the manual override lever.
Pushing the wrench button vents chamber A and B past the manual override vent ball. Because the manual override vent is larger than the regulating orifice, the pressures in chambers A and B decrease to ambient pressure.
Since there is no longer any diaphragm force on the actuator, the handle can be rotated against the closing torsion spring to open the butterfly.
When the handle is released, the torsion spring turns the butterfly valve to the closed position, and the button is returned to the closed position by the action of the vent ball spring.
The override handle aligns with markings on the valve to provide an external indication of the butterfly valve position.
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ALL CFM56-5B ENGINES FOR A319-A320-A321
ENGINE SYSTEMS Jan 03
CFMI PROPRIETARY INFORMATION
CFM56-5B TRAINING MANUAL
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