-
661 pph (300 kg/h) hot flow.
EFG
.
LOW RETURN FUEL FLOW
CTC-201-134-02
EFFECTIVITY
73-11-50 Page 11
ALL CFM56-5B ENGINES FOR A319-A320-A321
ENGINE SYSTEMS Jan 03
CFMI PROPRIETARY INFORMATION
EFG FUEL RETURN VALVE CFM56-5B TRAINING MANUAL
High return flow operation.
If the engine oil temperature continues to increase, and reaches 95°C, the ECU energizes the V2 solenoid.
The ECU continues to send an electrical signal to the V1 solenoid, which maintains the shut-off valve open, through Psf fuel pressure.
The V2 solenoid opens the valve, allowing Psf pressure to the top of the pilot valve’s piston, which now moves left.
The hot fuel from the IDG oil cooler now passes through the pilot valve, and is directed to the flow control valve spring side.
The flow control valve moves to the left, completely opening the orifice connected to the A/C fuel return circuit.
The compensating valve adjusts the flow of the return fuel to a constant value of:
- 880 pph (400 kg/h) cold flow.
- 1322 pph (600 kg/h) hot flow.
EFFECTIVITY ALL CFM56-5B ENGINES FOR A319-A320-A321 CFMI PROPRIETARY INFORMATION 73-11-50 ENGINE SYSTEMS Page 12 Jan 03
EFG
.
HIGH RETURN FUEL FLOW
CTC-201-135-01
EFFECTIVITY
73-11-50 Page 13
ALL CFM56-5B ENGINES FOR A319-A320-A321
ENGINE SYSTEMS Jan 03
CFMI PROPRIETARY INFORMATION
CFM56-5B TRAINING MANUAL
EFG
FUEL RETURN VALVE
Modulated idle.
The High return fuel flow may, in some cases, not be enough to cool down the engine oil temperature.
Therefore, the engine minimum idle speed may be increased to create a higher fuel flow, resulting in more effective oil cooling in the main oil/fuel heat exchanger.
The modulated idle operation depends upon the oil temperature and the A/C ground or flight condition.
On ground, no IDG modulated idle is required.
In flight, the modulated idle operation is set when the oil temperature reaches 106.2°C.
N2 speed then accelerates, according to a linear schedule, up to a maximum of 11731 rpm, which corresponds to an oil temperature of 128°C.
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