EFG
.
CTC-201-033-02
EFFECTIVITY
73-21-18 Page 33
ALL CFM56-5B ENGINES FOR A319-A320-A321
ENGINE SYSTEMS Jan 03
CFMI PROPRIETARY INFORMATION
CFM56-5B TRAINING MANUAL
EFG
HYDROMECHANICAL UNIT
Engine run condition.
When the FMV is in the run condition, the SOV signal supplied through the FMV shut-off shuttle valve is Pb.
The A/C shut-off solenoid plunger is de-energized and held in the ‘down’ position by magnetic latches.
In this position, the SOV pressure signal (Pb) supplied by the FMV shuttle valve, is able to pass through to the bottom of the shut-off shuttle valve.
Pcr pressure is supplied to the top of the shut-off shuttle valve and, because of the differential pressure (Pcr, Pb) across it, the valve is pushed down, allowing normal operation of the Delta P regulator and of the pressurizing and shut-off valve.
EFG
. .
.
CTC-201-275-01
EFFECTIVITY
73-21-18 Page 35
ALL CFM56-5B ENGINES FOR A319-A320-A321
ENGINE SYSTEMS Jan 03
CFMI PROPRIETARY INFORMATION
CFM56-5B TRAINING MANUAL
EFG
HYDROMECHANICAL UNIT
Engine shut-down by cockpit order.
The cockpit shut-down order is activated by the pilot who moves the Master lever to the “OFF” position.
This energizes the A/C shut-off solenoid coil and the magnetic latch force is overcome. Consequently the plunger moves up and ports Psf to the SOV line.
Because of the differential pressure (Psf, Pcr), the shut-off shuttle valve moves up to ensure pressurizing and shut-off valve closure and pump unloading (by-pass valve open).
EFG
. .
.
CTC-201-276-01
EFFECTIVITY
73-21-18 Page 37
ALL CFM56-5B ENGINES FOR A319-A320-A321
ENGINE SYSTEMS Jan 03
CFMI PROPRIETARY INFORMATION
CFM56-5B TRAINING MANUAL
EFG
HYDROMECHANICAL UNIT
ECU automatic engine shutdown during starting sequence on the ground.
In the event of an abnormal starting sequence on the ground, the ECU determines a need to shut down the engine and triggers a shutdown function.
The shutdown function commands the FMV servo piston towards the minimum stop.
At an FMV angle of approximately 10 degrees, the FMV servo piston’s minimum stop screw contacts the plunger of the FMV shut-off shuttle valve.
As the metering valve modulated pressure (Pz) is low enough, the servo overcomes the force of Psf pressure exerted on the other side of the FMV shut-off shuttle valve plunger, and continues to move towards the minimum stop position.
At an FMV angle of approximately 7 or 8 degrees, the FMV shut-off shuttle valve plunger moves far enough to switch output pressure (SOV signal) from Pb to Psf.
The FMV continues moving until the metering valve servo contacts the minimum stop (FMV angle of 5 degrees). 中国航空网 www.aero.cn 航空翻译 www.aviation.cn 本文链接地址：TRAINING MANUAL CFM56-5B ENGINE SYSTEMS 培训手册 CFM56-5B 发动机系统(48)
