Cooling Pack System SchematicFigure 11B
LEFT PACK
TEMP
CONTROLLER
BLEED AIRFROM L ENGINE/APU/GROUNDSOURCE
L PACK FLOWCONTROL ANDSHUT OFFVALVE
CONDITIONEDAIR
COLD AIR
COOL AIR
WARM AIR
HOT AIR
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A
757
MAINTENANCE MANUAL
28V DC 28V DC OPEN
2
SOLENOID
POWER
B SUPPLY
LEFT PACK MANUAL CONTROL
FLOW CONT CLOSE
(PUSH TO OPENPULL TO CLOSE)P11
SOLENOIDA L PACKHIGH FLOWPACK OVHTBACK UP
190`F (88`C)TEMP CONTRLCARD
L PACK+AUTO/MAN
PACK NOT OVHTHIGH FLOWRELAY
TORQUE MOTORPACK OUTLET
L PACK-OVHT SW L PACK RESET
COMPRESSOR OVHT
BACK UP SW
TEMP CONTRLCARD 490`F (254`C) NOT CLOSED
CLOSED
28V DC FCV
COMPRESSOR OUTLET PACK INOP LIGHT
L PACK INOP LTOVHT SW
POSITION SWPACK INOP LIGHTCLOSE
EICAS CMD
L PACK OFF LT
3 SEC
L PACK FLOW CONTROLAND SHUTOFF VALVEFCV
OFF
AUTOPACK ON
OPEN
STBY N
CMD
STBY C
STBY W
3 SEC PACK ON
L PACK SELECTOR SWITCH ECS PACKON/OFF
HIGH FLOW
SAME AS
INTERNALSAIR CONDITIONING CONTROL PANEL
L FCV CLOSED
INHIBIT
AUTO
L PACK FLOW
FAILED HIGH FLOW ON
CONTROL CARD
ECS PACK HI/LOL PACK
AUTO/MAN 3R ENGINE ON R ENG ON
R PACK FLOWL ECS BLEED
1 SEC RELAY
CONTROL CARD 28V DC HIGH
R ENG OFF
CONFIG CARDR ENGINE OFF HIGH FLOW INHIBIT
FLOW
425`F (218`C)CMD
+
R ENGINE SPEED CARD
R FCV CLOSED
ON
-
L RECIRC FAN ON
-
L AIR SUPPLY PRSOV L PRSOV CLOSED AIR MIN MAX R AIR SUPPLY PRSOV R PRSOV CLOSED
CURRENTOFF
SCHEDULECOMPRESSOR5 MA
GROUND GND
L RECIRCOUTLETFAN CURRENT
TEMP SENSOR
AIR/GND RELAYL PACK FLOW CONTROL CARD 1 SYS 2
FAULTPROCESSING
+ _____ AND STORAGE FAULT
NOTES: INHIBIT
1
ALL INPUTS INVERTED GROUND
LEFT SYSTEM SHOWN, RIGHT SYSTEM SIMILAR L PACK TEMP CONTROLLER
INPUT = LOGIC "1".
2
ON GUN 001-005,
POWERED BY L BUS.
ON GUN 006-999,
POWERED BY THE L XFR BUS.
Pack Flow Control Operation Schematic
Figure 12
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MAINTENANCE MANUAL
(e)
The air-cycle-machine turbine decreases the pressure and the temperature of the air. The energy from the expanded air makes the air cycle machine operate. Subsequently, the air again flows through the condensor. This causes the air temperature to increase as it goes from the air cooling pack.
(f)
The low-limit-control valve and the temperature control valve lets some of the air go around the air cycle machine. This hot air flows to the turbine outlet to prevent ice. Also, because a smaller amount of air flows through the air cycle machine, the speed of the air cycle machine decreases. This causes the compressor outlet temperature to decrease and the air-cooling-pack-outlet temperature to increase.
(g)
Small amounts of air flow through the tubes in the air cooling pack. This air has special uses. Some tubes supply air to the low-limit-control valve to cause it to open or close. Some air goes from the secondary heat exchanger through a tube to get water from the water extractor. Also, some air goes from the compressor flows to the condensor and the turbine outlet to prevent ice.
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