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A servo valve, to override and/or hold the poppet valve open.
Twenty fuel nozzle operation.
A three-way dual solenoid, located in the HMU, is de-energized and low fuel pressure (Pcr) is applied to both ends of the poppet valve.
A spring keeps the poppet valve in the BSV open, allowing fuel to flow from the inlet port to the outlet port.
EFG
20 FUEL NOZZLES OPERATION
CTC-201-106-01
EFFECTIVITY
73-11-70 Page 7
ALL CFM56-5B ENGINES FOR A319-A320-A321
ENGINE SYSTEMS Jan 03
CFMI PROPRIETARY INFORMATION
CFM56-5B TRAINING MANUAL
EFG
BURNER STAGING VALVE
10 fuel nozzle operation.
To close the poppet valve, an electrical signal is applied to the dual solenoid valve in the HMU.
This allows high pressure fuel (Pc) to be directed to the top of the valve, to close the poppet.
In the closed position, the differential pressure moves the valve down.
A bleed orifice in the poppet keeps the pressure in the spring cavity at Pcr pressure.
There are two position switches located on the valve, one for ECU channel A and one for channel B. The switches click closed when the poppet valve is about to close.
A calibrated orifice allows a small amount of fuel to pass to the nozzles to avoid fuel nozzle tip coking.
EFG
10 FUEL NOZZLES OPERATION
CTC-201-107-01
EFFECTIVITY
73-11-70 Page 9
ALL CFM56-5B ENGINES FOR A319-A320-A321
ENGINE SYSTEMS Jan 03
CFMI PROPRIETARY INFORMATION
CFM56-5B TRAINING MANUAL
EFG
BURNER STAGING VALVE
Failsafe Operation.
The BSV is equipped with a servo valve installed in parallel with the fuel supply inlet port.
When the inlet pressure reaches 250 psi, the servo valve moves down, thus restricting and blocking the Pcr port.
The bleed orifice in the poppet enables the pressure to be balanced in the top and bottom cavities.
The poppet valve cavity is now ported to Pc fuel pressure, and the spring lifts the poppet valve.
Metered fuel passes through the valve and is delivered to the fuel nozzles.
The two position switches click open just as the poppet valve begins to open.
EFG
FAILSAFE OPERATION
CTC-201-108-02
EFFECTIVITY
73-11-70 Page 11
ALL CFM56-5B ENGINES FOR A319-A320-A321
ENGINE SYSTEMS Jan 03
CFMI PROPRIETARY INFORMATION
EFG BURNER STAGING VALVE CFM56-5B TRAINING MANUAL
Burner staging valve control.
The control laws logic in the ECU calculates the BSV position demand.
The process has four parts:
- BSV status.
- Fuel/air ratio calculations.
- BSV inhibition logic.
- BSV position demand logic.
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