Effectivity
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 36-CONTENTS
 GUN Page 3 Feb 18/02
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A 747-400 MAINTENANCE MANUAL
 CHAPTER 36 - PNEUMATIC SYSTEM
 TABLE OF CONTENTS_________________
 Chapter
 Section
 Subject Subject_______ _______  Page____  Effectivity___________
 VALVE - WING ISOLATION 36-11-07
 Maintenance Practices  201  ALL
 Removal/Installation  401  ALL
 BLEED AIR PRECOOLER SYSTEM 36-12-00
 Description and Operation  1  ALL
 General  1
 Precooler - Bleed Air  1
 Sensor - Fan Air Temperature  1
 Valve - Fan Air Modulating  1
 Operation  2
 PRECOOLER - ENGINE BLEED AIR 36-12-01
 Removal/Installation  401  ALL
 Inspection/Check  601  ALL
 Approved Repairs  801  ALL
 SENSOR - FAN AIR TEMPERATURE 36-12-02
 Removal/Installation  401  ALL
 VALVE - FAN AIR MODULATING 36-12-04
 Maintenance Practices  201  ALL
 Removal/Installation  401  ALL
 ENGINE BLEED AIR INDICATION SYSTEM 36-20-00__________________________________
 Component Location  101  ALL
 Component Index
 Component Location
 INDICATING SYSTEM - ENGINE BLEED 36-21-00
 AIR PRESSURE
 Description and Operation  1  ALL
 Adjustment/Test  501  ALL
 SENSOR - BLEED AIR PRESSURE 36-21-02
 Removal/Installation  401  ALL
 SWITCH - BLEED AIR OVERPRESSURE 36-21-03
 Removal/Installation  401  ALL
 Adjustment/Test  501  ALL
 TRANSMITTER - DUCT PRESSURE 36-21-01
 Removal/Installation  401  ALL

 36-CONTENTS
 GUN Page 4 Feb 18/02
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400 MAINTENANCE MANUAL
 CHAPTER 36 - PNEUMATIC SYSTEM
 TABLE OF CONTENTS
_________________
 Chapter Section
 Subject_______  Subject ____ Effectivity_______ Page ___________
 INDICATING SYSTEM - ENGINE BLEED 36-22-00
 AIR TEMPERATURE

 Description and Operation 1 ALL Sensor - Bleed Air Temperature 1 Switch - Bleed Air 1
 Overtemperature SENSOR - BLEED AIR TEMPERATURE 36-22-02 Removal/Installation 401 ALL SWITCH - BLEED AIR 36-22-01
 OVERTEMPERATURE Removal/Installation 401 ALL Adjustment/Test 501 ALL
 36-CONTENTS
 GUN Page 5 Feb 18/02
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400 MAINTENANCE MANUAL
 PNEUMATIC SYSTEM - DESCRIPTION AND OPERATION
____________________________________________
 1.  General_______
 A.  The pneumatic system controls the flow, pressure, and temperature of the engine bleed air that is used for these systems:
 -Airplane pressurization and environmental control system (ECS)
 -Wing leading edge flap drives
 -
Engine cowl and wing thermal anti-icing

 -
Engine cross-starting

 -Hydraulic pump operation and reservoir pressurization
 -
Potable water tank pressurization.

 B.  
The engine bleed air supply system is operated by the engine bleed switches on the bleed control module in the flight compartment. The Air Supply Control and Test Unit (ASCTU) monitors the engine mounted air supply components and the distribution system. The ASCTU receives inputs from the bleed control module and sends the appropriate commands to the individual air supply components.

 C.  
Each engine supplies compressed air to the pneumatic system. There are two sources of bleed air available from the engine; intermediate pressure (8th-stage) and high pressure (15th-stage). Engine fan air is used to remove heat from the engine bleed air in the precooler.

 D.  
The pneumatic system can also be pressurized with a ground air source or the APU. The APU is also used as a secondary pressure source in flight.

 E.  
The pressure and temperature of the pneumatic ducts can be monitored on the Engine Indicating and Crew Alerting System (EICAS). A SYS FAULT light and an EICAS message will be shown for an overpressure or an overtemperature condition.
　
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