-SYS FAULT light will come on
-caution EICAS message, BLEED
-status EICAS message, BLEED PRV ENG
-an aural warning will be heard.
(c)
The high pressure controller will close the HPSOV before high stage engine pressure reaches 105 psig. If the HPSOV does not close and high stage engine pressure is greater than 127 | 10 psig, it will cause the following indications:
-SYS FAULT light to come on
-caution EICAS message, BLEED
-status EICAS message, BLEED HP ENG.
(d)
These indications will stop if the HPSOV closes or the pressure is less than 127 | 10 psig.
(e)
The indication light logic is in the ASCTU. The SYS FAULT light will come on when any of the following conditions occur: 1) The HPSOV does not close after it is given the command
signal to close. 2) The PRV stays open when there is an overpressure condition (78 | 2 psig) for more than 5 seconds. 3) The PRV does not close after it is given the command signal to close.
(f)
The HPSOV and the PRV will close when the overtemperature switch determines that there is an overheat condition. The overtemperature switch operates if the temperature increases above 450 °F (232 °C). Anytime there is an overheat condition for more than 5 seconds, the status EICAS message (BLEED OVHT) will be shown and the SYS FAULT light will come on.
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MAINTENANCE MANUAL
AIR SUPPLY CONTROL AND TEST UNIT (ASCTU)
Engine High Pressure Control SchematicFigure 17 (Sheet 1)
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MAINTENANCE MANUAL
TO SUPPLY
DISTRIBUTION PRESSURE REGULATING
AND SHUTOFF VALVE (PRSOV)
C SHT 1
SHT 1 C BLEED AIR OVERPRESSURE SWITCH
BLEED AIR
OVERTEMPERATURE
SWITCH OVBD
FULLY OPEN
FULLY CLOSED
PRV POSITION SW
PRESSURE REGULATING VALVE (PRV)
FAN AIR MOD
17TH-STAGE
FAN
8TH 15TH-
AIR
STAGE STAGE
ENGINE BLEED AIR
SUPPLY AIR EXHAUST AIR
SHT 1 A
FULLY OPEN
FULLY CLOSED HPSOV POSITION SW HI PRESSURE SHUTOFF VALVE (HPSOV)
PC
PH-PC
PHL
AUTO. PHH
SHUTOFF
SHT 1 B
HI PRESSURE CONTROLLR (HPC)
H SHT 1 C SHT 1 CONTROLLER (PRC) E SHT 1 D SHT 1 PRESSURE REGULATING CLOSED AUTO
C SHT 1
G SHT 1
C SHT 1
C SHT 1
C SHT 1
F SHT 1
High Pressure Control and Pressure Regulating Control Schematic
Figure 17 (Sheet 2)
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MAINTENANCE MANUAL
NOTE: ALL ENGINES SIMILAR
Pressure Regulating And Shutoff Valve SchematicFigure 18
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MAINTENANCE MANUAL
INTERFACE UNITS
____LEFT SYSTEM SHOWN;NOTE:
RIGHT SYSTEM SIMILAR.
Wing Isolation Valve Schematic
Figure 19
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