EFG
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CTC-201-277-01
EFFECTIVITY
73-21-18 Page 39
ALL CFM56-5B ENGINES FOR A319-A320-A321
ENGINE SYSTEMS Jan 03
CFMI PROPRIETARY INFORMATION
CFM56-5B TRAINING MANUAL
EFG
HYDROMECHANICAL UNIT
Reset function.
If the A/C solenoid was used to initiate engine shut-down, (Pilot action - Master Lever OFF), the ECU must still command the FMV below 8 degrees in order to port Psf and hydraulically reset the solenoid back to a run state.
During the starting sequence, the master lever is “ON”, therefore the A/C solenoid coil is de-energized.
The ECU control logic sends an electrical signal to the FMV torque motor, which positions the FMV and FMV shut-off shuttle valve to port Psf pressure to the top of the A/C shut-off solenoid valve plunger.
This Psf pressure, applied to the top of the solenoid plunger, is only opposed by Pb at the bottom and so, the plunger moves down, hydraulically resetting the valve.
The ECU reset function then stops and the FMV is positioned to deliver fuel.
EFG
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CTC-201-286-01
EFFECTIVITY
73-21-18 Page 41
ALL CFM56-5B ENGINES FOR A319-A320-A321
ENGINE SYSTEMS Jan 03
CFMI PROPRIETARY INFORMATION
CFM56-5B TRAINING MANUAL
EFG
HYDROMECHANICAL UNIT
Servo flow regulation system.
The servo flow regulator system regulates the flow of fuel to actuators.
The system is composed of six flow regulators :
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Fuel Metering Servo Valve (already described).
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Variable Stator Vane (VSV).
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Variable Bleed Valve (VBV).
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Transient Bleed Valve (TBV).
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High Pressure Turbine Clearance Control (HPTCC).
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Low Pressure Turbine Clearance Control (LPTCC).
The regulators use three and four-way pilot valves to produce a defined pressure versus flow schedule.
There are also 2 solenoid valves:
- The Burner Staging Valve (BSV).
-The A/C shut-off solenoid (already described).
EFG
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CTC-201-273-01
EFFECTIVITY
73-21-18 Page 43
ALL CFM56-5B ENGINES FOR A319-A320-A321
ENGINE SYSTEMS Jan 03
CFMI PROPRIETARY INFORMATION
CFM56-5B TRAINING MANUAL
EFG
HYDROMECHANICAL UNIT
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