*
LVDT -linear variable differential transformer

*
MACH -mach number

*
MFD -multi-function display

*
RVDT -rotary variable differential transformer

*
SVA -stator vane actuator

*
TCA -turbine cooling air

*
TCC -turbine case cooling

*
TRA -throttle resolver angle

*
TVBC -turbine vane and blade cooling

*
TVC -turbine vane cooling

*
VSV -variable stator vane

EFFECTIVITY BEJ ALL  75-00-00 
Page 2 
D633W101-BEJ  Jan 05/2004 

PW4000 SERIES ENGINES

777 AIRCRAFT MAINTENANCE MANUAL

AIR -INTRODUCTION

EFFECTIVITY BEJ ALL  75-00-00 
Page 3 
D633W101-BEJ  Sep 05/2002 

PW4000 SERIES ENGINES

777 AIRCRAFT MAINTENANCE MANUAL

AIR -INTRODUCTION

EFFECTIVITY BEJ ALL POST SB 777-71-0032  75-00-00 
Page 4 
D633W101-BEJ  Jan 05/2004 

AIR -GENERAL DESCRIPTION

General
The electronic engine control (EEC) controls and monitors these engine air cooling and compressor control subsystems:
*
Engine external accessories cooling

*
Turbine case cooling

*
Turbine vane and blade cooling

*
Compressor stator vane control

*
Compressor bleed control

*
Thrust balance control.

Engine External Accessories Cooling
The engine external accessories cooling system uses fan air to cool engine components and the area between the engine and the thrust reverser. Tubes send air to cool specific components. The EEC controls the nacelle zone ventilation shutoff valve to let fan air cool the area under the thrust reverser. PS3 servo air pressure operates the valve.
Turbine Case Cooling
Fan air cools the high pressure turbine (HPT) and the low pressure turbine (LPT) cases. This decreases the turbine blade tip clearance and increases the life of the LPT case. The EEC controls both actuators in the TCC air valve actuator. Servo fuel pressure moves the actuators to modulate the HPT and LPT air valves.
EFFECTIVITY BEJ ALL BEJ ALL POST SB 777-71-0032
Turbine Vane And Blade Cooling
The turbine vane and blade cooling system uses 12th stage air to cool the HPT 2nd stage vanes and blades. This increases engine performance. The EEC controls the TVBC air shutoff valve solenoid and the TVC air valve actuator. PS3 servo air pressure closes the poppet-type valves. Servo fuel pressure moves the TVC air valve actuator to modulate the air valve.
BEJ ALL
Turbine Vane And Blade Cooling
The turbine vane and blade cooling system uses 12th stage air to cool the HPT 2nd stage vanes and blades, the LPT 3rd through 5th stage vanes, and the number 3 bearing buffer air. This increases engine performance. The EEC controls the TVBC air shutoff valve solenoid. PS3 servo air pressure closes the poppet-type valves.
　
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本文鏈接地址：777 AMM 飛機維護手冊 發動機引氣 Engine Air PW 777 AIRCRAFT MAINTENANCE MANUAL(3)