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.The EICAS memo message APU RUNNING is displayed whenAPU N1 is 95% and higher.APU bleed air is supplied through the center sectionof the bleed air duct.The check valve in the APU supply line prevents reverse flowof bleed air from the duct into the APU.Bleed duct overheat protection is provided in the APU bleed air system to detectleaks.If the APU shuts down for an overheat, it cannot be restarted.Ground Bleed Air SupplyExternal connectors are provided to connect a ground source of high pressure airdirectly to the bleed air duct.Check valves prevent reverse flow of bleed air from the bleed air duct to theconnectors.Copyright © The Boeing Company.See title page for details.2.40.2 D6-30151-425 October 1, 2000 Air Systems -Bleed Air System Description747 Operations ManualBleed Air Duct SystemThe left and right isolation valves separate the bleed air duct into three sections:left, center, and right.The system normally operates with the isolation valvesopen.The valves are controlled by the left and right isolation valve switches.Duct Leak and Overheat Detection SystemA bleed duct overheat system is provided to detect leaks.If a duct leak is detected,the bleed air duct section affected can be isolated by closing the respectiveisolation and engine bleed air valves.Bleed Air System Non-normal OperationsIf a bleed duct leak is detected, closing the respective isolation and engine bleedvalves prevents further air loss.If the center duct section is isolated, pushing the Aft Cargo Heat switch off closesthe electrically operated aft cargo heat valves to prevent cabin air flowing inreverse through the aft cargo heat supply duct and into the leaking center dectsection.All temperature zones operate in backup temperature control modewithout trim air.Potable water pressurization and cargo smoke detection are notavailable.If the left or right duct section is isolated, the respective leading edge flaps operateelectrically in secondary mode.The respective hydraulic demand pump one orfour is selected OFF to avoid the EICAS alert message HYD PRESS DEMANDfrom being displayed during approach.A maximum of one air conditioning packon assures sufficient thrust is available from the two engines which supply air tothe unaffected duct sections.The EICAS alert message BLEED is displayed for bleed overpressure, or PRV orHP bleed valve failed to close when commanded.If the respective NAI VALVEmessage is displayed after pushing the related Nacelle Anti-ice switch ON, thePRV is closed because the HP bleed valve failed open and nacelle anti-ice is notavailable.Copyright © The Boeing Company.See title page for details.December 01, 1999 D6-30151-425 2.40.3 Air Systems -Bleed Air System Description747 Operations ManualBleed Air System SchematicAIR CONDITIONING PACKS1 2 3NORM NORM NORMA A AOFF OFF OFFB B BAUTOOFF ONLEWINGL ISLN R ISLNFLAPSANTI-ICEVALVE VALVEAUTOTOOFF ONP PDUCT DUCT HYD SYS 3LEFTPRESSURE PRESSURE RESERVOIRWINGPRESSANDTRIM AIRAUXENGINESONAIR DRIVEN1 & 2HYDRAULIC3DEMAND PUMPENGINEONHYD SYS 4BLEEDAFT CARGO HTCARGO SMOKEOFFVALVE RESERVOIRDETECTIONONPRESS3OFFTEMPPOTABLE WATER 4AUTOENGINEPRESSURIZATIONONON BLEEDOFFVALVENACELLETHRUSTANTI-ICE4REVERSEROFFAUTOONFANPRECOOLER NACELLEANTI-ICEGRD3SOURCESIPBLEEDTHRUSTAPUPRV3REVERSERAPU BLEED AIRONISOLATIONVALVEHP BLEEDVALVESTARTFANVALVEPRECOOLERAPU4IPBLEEDPRV4HP BLEEDSTARTVALVECopyright © The Boeing Company.See title page for details.2.40.4 D6-30151-425 December 01, 1999 747 Operations ManualAir Systems Chapter 2EICAS Messages Section 50Air Systems EICAS MessagesThe following EICAS messages can be displayed.EICAS Alert MessagesMessage Level Aural ConditionBLD DUCT LEAK Caution Beeper Bleed air leak or overheat along the left,L, C, R center, or right duct section.Message Level Aural ConditionBLD OVHT/PRV Advisory Engine bleed air overheat or PRV failed1, 2, 3, 4 closed.BLEED 1, 2, 3, 4 Advisory Engine bleed air overpressure, or HP bleedvalve or PRV failed to close whencommanded.Message Level Aural Condition>BLEED 1, 2, 3, 4 Advisory Engine Bleed Air switch OFF, engineOFF operating, and engine bleed air valveclosed.BLEED HP ENG Advisory HP bleed valve failed closed.1, 2, 3, 4BLEED ISLN L, R Advisory Isolation Valve switch position and valveposition disagree.Message Level Aural Condition>BLEED ISLN Advisory APU bleed isolation valve positionAPU disagrees with commanded position.Copyright © The Boeing Company.See title page for details.April 01, 2001 D6-30151-425 2.50.1 Air Systems -EICAS Messages747 Operations ManualMessage Level Aural ConditionCABIN ALT Caution Beeper Both cabin altitude controllers inoperativeAUTO or both Outflow Valve Manual switchesON.CABIN Warning Siren Cabin altitude exceeds 10,000 feetALTITUDE>E/E CLNG Advisory Fault in equipment cooling system andCARD system not fully functional.Messageinhibited in flight [ Pobierz caÅ‚ość w formacie PDF ]