sds1230-21-51-00

COOLING PACK SYSTEM

AIRCRAFTMAINTENANCE MANUAL

EFFECTIVITY: 21-51-00

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COOLING PACK SYSTEM

INTRODUCTION

The cooling pack system automatically controls the temperature anddecreases the humidity of the cockpit and cabin air. It has two coolingpacks installed in the forward part of the wing-to-fuselage fairing.

DESCRIPTION

The two cooling packs are attached to the fuselage with rods andbrackets. Some of these rods have flexible shock mounts at one end.The air passages that connect the packs to the fuselage have flexiblecouplings which are safetied with secondary beads.

The main components of the system are:

− Pack valve.

− Air cycle machine.

− Dual heat exchanger.

− Condenser/mixer.

− Water collector.

− Pack overpressure switch.

− Pack overtemperature switch.

− Pack setdown switch.

− Pack duct overtemperature switch.

− Temperature switch.

− Pack ducts.

The figure ″COOLING PACK SYSTEM - MAIN COMPONENT LOCA-TIONS″ shows the location of the main components of the system.


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ZONE191

PACKOVERPRESSURE

SWITCH

PACK VALVE

FAN

CONDENSERMIXER

PACK DUCTOVERTEMPERATURESWITCH

DUAL HEATEXCHANGER

ACM

PACKSETDOWNSWITCH

PACKOVERTEMPERATURESWITCH

WATERCOLLECTOR

AIR CONDITIONING/PNEUMATIC

C H

CKPT RECIRC PASS CABIN

GASPER

WING 1 A/ISTAB A/ISTARTER 1

XBLEED

WING 2 A/ISTARTER 2

BLEED 1 APU BLEED BLEED 2

ATTD

AUTOCLOSED OPEN

PACK 1 PACK 2

GNDCONN

OPEN

PULL KNOB FOR MANUAL CONTROL

C H

LEAK LEAK

DET. ADET. B

A

B

PACK 1CONTROLSWITCH

PACK 2CONTROLSWITCH

145AMM210092.MCE C

COOLING PACK SYSTEM - MAIN COMPONENT LOCATIONS



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COMPONENTS

PACK VALVE

There are two pack valves, one for each refrigeration pack.

The pack valve is part of the air conditioning system. It controls thepressure level from the bleed air supply to the refrigeration pack inthe Environmental Control System (ECS). It also shuts off the bleedair supply to the refrigeration pack when it receives the applicablesignal.

The pack valve is a butterfly type valve. It operates pneumatically.

The butterfly valve has a shaft and disc set installed in the valvehousing. The valve shaft is connected to the actuator by a linkagecrank and linkage. The supply air on the upstream side of the valvegoes through a filter.

The pressure controller bleeds servo pressure to control the regulatedpressure.

When the unit gets a 28 V DC electrical signal, the shutoff solenoidenergizes. This moves the valve to a more open position. When thiselectrical signal is removed, the shutoff solenoid de-energizes, andthe valve closes.

When the system is set to high schedule (Ref. 21-50), it sends a 28 VDC electrical signal to the schedule solenoid. This pressurizes thereset piston. When the reset piston is pressurized, there is more forceon the lever to keep the poppet valve closed. Less servo pressurebleeds, so the butterfly valve stays in a more open position (highschedule).

The valve shaft moves an actuator arm when the valve opens orcloses. The actuator arm operates the closed position switch. Theswitch sends a signal to the EICAS when the valve is fully closed.

You can lock the valve in the closed position with the lock plug asfollows:

− Remove the locking screw from the actuator housing. It has aretaining cable.

− Turn the valve to the closed position. The locking crank has a hexhead so you can put a wrench on it to turn the valve.

− Install the locking screw in the hole in the actuator housing that isnearest to the locking crank. This will lock the valve in the closedposition.The figure ″PACK VALVE - COMPONENT DETAILS AND LOCA-TION″ shows the location of the pack valve and its maincomponents.

AIRCRAFTMAINTENANCEMANUAL


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PACK VALVE - COMPONENT DETAILS AND LOCATIONSHEET 1



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THIS PAGE INTENTIONALLY LEFT BLANK


EFFECTIVITY: ALL

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LOC

KIN

G IN

ST

R.

PUSHSOLENOID(SHUTOFF)

HOLE FOR THELOCKING SCREW TOLOCK THE VALVE INTHE CLOSEDPOSITION

PUSHSOLENOID(SCHEDULE)

LOCKINGCRANK

BELLOWSADJUSTMENT

PRESSUREREGULATINGADJUSTMENT CLOSED

POSITIONSWITCH

ELECTRICALCONNECTOR

CONTROLCOVER

CONTROLHOUSING

LOCKINGSCREW

ACTUATORCOVER

ACTUATORHOUSING

VALVEHOUSING

BUTTERFLYDISC

THE AIR FILTERIS UNDER THISPLUG.

PREGSUPP

SERVP

FLOW

CLOSE

AMBP

SERVOACTUATOR

PISTON

DIAPHRAGM

FILTER

BUTTERFLYVALVE

LOCKPIN

SCHEDULE SOLENOID(SHOWN DE-ENERGIZED)

SHUTOFF SOLENOID(SHOWN DE-ENERGIZED)

CONTROLLEVER

CONTROLPISTON

RESETPISTON

CONTROLBELLOWS

POPPETVALVE

RESET PRESSURETEST PORT

CLOSEDPOSITIONSWITCH

MANUALLYTURN ANDLOCK CLOSED

145AMM210174.MCE

XX

XX

XX

XX

XX

XX

XX

XX

XX

XX

XX

XX

XX

XX

XX

XX

XX

XX

XX

XX

XX

XX

PACK VALVE - COMPONENT DETAILS AND LOCATIONSHEET 2



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DUAL HEAT EXCHANGER

There are two dual heat exchangers, one for each refrigeration pack.

The dual heat exchanger has three circuits. The primary circuitremoves heat from the bleed air before it goes to the compressorsection of the air cycle machine. The secondary circuit removes heatfrom the compressor air before it goes to the condenser section of thecondenser mixer and the turbine section of the air cycle machine. Thefan section of the air cycle machine pulls air through the ram circuit tomove the heat that the other two circuits removed.

The primary and secondary sections of the core are brazed together.Each section has an inlet and an outlet duct. The core uses aplate-and-fin configuration.

The dual heat exchanger attaches to the aircraft with two mounts thatare welded to the unit. There is a three-way mount that has bushingsto isolate the unit from vibration. There is also a one-way mount thatis brazed to the ram-air outlet header.

The figure ″COOLING PACK SYSTEM - DUAL HEAT EXCHANGER″shows the location of the dual heat exchanger and its maincomponents.



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ZONE191

DET. A

A

DET. B

B

CONDENSERMIXER

ACM

WATERCOLLECTOR

DUAL HEATEXCHANGER

FAN

ONE-WAYMOUNT

PRIMARYOUTLET DUCT

SECONDARYINLET DUCT

SECONDARYOUTLET DUCT

LOCATING LUG(USED DURINGINITIAL ASSEMBLY)

PRIMARYINLET DUCT

CORESECTION

RAM AIRINLET

TREE-WAYMOUNT

FAN INLETDIFFUSERHOUSING

DUAL HEAT EXCHANGER(FAN INLET

DIFFUSER HOUSING)DIFFUSER

FAN OUTLET

FAN INLET

RAM AIRCOOLING FAN

AIR CYCLE MACHINE(REF.)

SECTION C-C

C

TO OVERBOARD

TO FAN(OUTER)

FROM FAN(INNER)

145AMM210176.MCE C

COOLING PACK SYSTEM - DUAL HEAT EXCHANGER



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AIR CYCLE MACHINE

There are two Air Cycle Machines (ACM), one for each refrigerationpack.

The external structure of the ACM has three components: a turbinehousing, a compressor housing and a fan housing. Its internalstructure has a turbine rotor, compressor rotor and a cooling fan.

The three rotors turn axially as one assembly. The turbine rotor is onone end, the cooling fan is on the other end and the compressor rotoris between them. Shaft assemblies are on either side of the compres-sor rotor. There are thrust bearing and journal bearing surfaces in theshaft assembly adjacent to the turbine rotor. One more journal bear-ing surface is in the shaft assembly adjacent to the cooling fan.

The figure ″COOLING PACK SYSTEM - AIR CYCLE MACHINE″shows the main parts and a cutaway view of the unit.



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COMPRESSORHOUSING

FAN INLET(OUTER)

FAN OUTLET(INNER)

TURBINEHOUSING

TURBINEOUTLET

TURBINEINLET

FANHOUSING

TURBINEROTOR

COMPRESSORROTOR

FAN

FAN-ENDSHAFT

ASSEMBLY

TURBINE-ENDSHAFT

ASSEMBLYFROM PACK

BY-PASS DUCT(HOT AIR)

COMPRESSORINLET

COMPRESSOROUTLET

145AMM210112.MCE A

COOLING PACK SYSTEM - AIR CYCLE MACHINE



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CONDENSER/MIXER

There are two condenser/mixers in each aircraft, one for eachrefrigeration pack.

The condenser/mixer has three sections: a condenser, a mixer and awater collection section.

The mixer section is welded to the condenser section.

Air from the compressor of the Air Cycle Machine (ACM) goes throughthe secondary section of the dual heat exchanger where some of theheat is removed. The air then goes into the condenser inlet. Thecondenser core decreases the temperature of the air. Airflow throughthe mixer section removes some of the heat from the core. Thedecreased temperature and the increased pressure causes thecondensation of water that is in the air. The water then flows to thewater collector and out through the water drain. The water flows to anozzle that applies a spray of water to the ram-air inlet duct of theheat exchanger.

Cold air from the turbine section of the ACM flows into the mixer inlet.This air is mixed with recirculated cabin air. The mixed air is warmerthan the air from the ACM. Air in the mixer section then flows throughthe core of the condenser section. In the core, it gets some more heatfrom the core. The air then goes to the cabin distribution system.

WATER COLLECTOR

The water collector is installed between the secondary heat exchangeroutlet and the ACM turbine inlet duct. It removes the water producedin the secondary heat exchanger outlet. Swirl vanes installed at theduct inlet increase the water droplet formation in the main air stream.A helix flow pattern in the straight duct section permits the coalescingof water droplets on the smooth duct wall. This is before collecting thewater in the collector body.

The collector body has a scupper section to divert water collected onthe duct from going into the main air stream flow again. A spray

nozzle removes the water accumulated at the bottom of the collector.

The figure ″COOLING PACK SYSTEM - CONDENSER/MIXERLOCATION″ shows its location.



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ZONE191

DET. A

DET. B

A

B

FROMTURBINE

FROMRECIRCULATION

FAN

FROM DUALHEAT EXCHANGER

TO CABIN

TO WATERSEPARATOR

FROM RAM AIR

145AMM210175.MCE B

COOLING PACK SYSTEM - CONDENSER/MIXER LOCATION



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PACK OVERPRESSURE SWITCH

There is one overpressure switch for each pack. The pressure switchis pneumatically operated. The switch gets pressure input at one endand has an electrical connector at the other. When the pressureincreases to the set point, the pressure switch closes a circuit betweenconnector pins A and B. When the pressure decreases to the setpoint, the switch opens the circuit between pins A and B and closesthe circuit between pins B and C.

PACK OVERTEMPERATURE SWITCH

There is one overtemperature switch for each pack. It is a single-pole,double-throw thermal switch. The switch gets temperature input atone end and has an electrical connector at the other. Each threadedswitch has a wrench flat for removal and installation.

PACK SETDOWN SWITCH

There is one setdown switch for each pack. It is a single-pole, double-throw thermal switch. The switch gets temperature input at one endand has an electrical connector at the other. Each threaded switchhas a wrench flat for removal and installation.

PACK DUCT OVERTEMPERATURE SWITCH

There is one duct overtemperature switch for each pack. It is asingle-pole, double-throw thermal switch. The switch gets temperatureinput at one end and has an electrical connector at the other. Eachthreaded switch has a wrench flat for removal and installation.

TEMPERATURE SWITCH

There is one temperature switch for each pack. The switch is hermeti-cally sealed, single-pole, single-throw, with snap-action and switch-ing, calibrated to close on temperature increase.

PACK DUCTS

The pack ducts are basically made from aluminum type AA6061-T6with diameters of 2.00 and 2.50 inches and thickness of 0.050 and0.10 inches. The primary heat exchanger outlet/compressor inlet ductis made from silicone rubber.

The figure ″COOLING PACK SYSTEM - SENSOR LOCATIONS″shows the location of the pack sensors.



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THERMAL SWITCH

PRESSURESWITCH

DET. A

DET. B

DET. C DET. DDET. E

DET. F

A

B

C

D

PACK OVERTEMPERATURESWITCH

PACK SETDOWN

SWITCH PACK DUCTOVERTEMPERATURE

SWITCH

E F

145AMM210118.MCE D

COOLING PACK SYSTEM - SENSOR LOCATIONS



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OPERATION

The pack valve controls the pressure at the inlet of the refrigerationpack. There are two regulator schedules for the valve: Normal (29.5psig at sea level) and High (42.5 psig at sea level). These values varywith altitude.

When both pack valves are open, they limit their downstream pres-sures in the Normal Mode. In case pack valve 2 is closed, pack valve1 will operate in the High Mode. In case pack valve 1 is closed andthe wing 1 anti-icing valve is closed, pack valve 2 will operate in theHigh Mode. These schedules are automatically selected and theycorrespond to a normal flow schedule or a schedule biased upward toachieve additional flow and cooling. Under some off-design or failureconditions, selecting high flow will cause the compressor outlettemperature to increase beyond the desired limits. The pack setdownswitch, set at 227 ± 6oC (440 ± 10oF), will be used to detect thistemperature and automatically set down the regulator schedule fromthe high flow mode to the normal flow mode by deactivating the highstage solenoid. This allows uninterrupted pack operation at the normalvalve schedule.

If the temperature at the compressor outlet is more than 243 ± 6oC(470 ± 10oF), the pack overtemperature switch sends a signal toclose the pack valve. This shuts down the pack. If the pressure at theoutlet of the pack valve is more than 55 ± 1.5 psig, the overpressureswitch sends a signal to close the pack valve. A re-initialization isnecessary to start the pack again.

The controlled bleed air comes in the pack and goes through thethrottle valve section of the dual temperature control valve. The airthat comes out of the throttle valve goes through the primary sectionof the heat exchanger to remove some of the heat.

After the air goes through the primary section of the heat exchanger,it goes through the compressor section of the air cycle machine. Thiscompresses and increases the temperature of the air. The hot,compressed air goes through the secondary section of the heat

exchanger. This removes much of the heat. The fan section of the aircycle machine pulls ram air through the ram circuit of the heatexchanger to remove heat from the primary and secondary sectionsof the heat exchanger.

When the air comes out of the secondary section of the heatexchanger, it goes to the condenser section of the condenser mixer.More of the heat is removed. Condensation occurs in the condensersection also. When the air leaves the condenser section of thecondenser mixer, it then goes through the water collector.

The water collector has a swirl vane that pushes the water to thewalls of the water collector. When the water moves further into thewater collector, gravity pushes the water to the bottom. At the bottomof the water collector, near its outlet, there is a water drain. The waterthat goes through the drain in the water collector, goes to a nozzlethat makes a spray on the secondary face of the heat exchanger.Evaporation of this water removes more of the heat from the heatexchanger.

After the air goes through the condenser section of the condensermixer, it goes to the turbine section of the air cycle machine. In thissection, the air becomes expanded. The expanded air supplies powerto turn the rotative assembly in the air cycle machine. The rotativeassembly has the turbine and compressor rotors and the cooling fan.When the air becomes expanded in the turbine section of the air cyclemachine, it also becomes cold. Hot bypass air is added fortemperature control. The air goes out of the turbine section and mixeswith the warmer air from the recirculation fan. The air then goesthrough the cold side of the condenser mixer.

There is a check valve downstream of the recirculation fan. Thisprevents airflow from the turbine section of the air cycle machinethrough the recirculation fan. The mixed air goes through the packoutlet to the cabin and crew distribution system (Ref. 21-20).

If the temperature of the air at the pack outlet is more than 93 ± 6oC(200 ± 10oF), the pack duct overtemperature switch sends a signal to



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close the pack valve. The pack duct overtemperature switch alsosends a signal to the EICAS. The EICAS display will show a cautionmessage ″PACK 1/2 OVHT″.

The figure ″COOLING PACK SYSTEM - SCHEMATIC DIAGRAM″shows the operation of the system.



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FROM LH BLEED SYSTEM

PACK VALVE

PACKOVERPRESSURE

SWITCH

RAM AIR

TO CREW PANEL

EMERGENCYVENTILATION

P F1 S S

+−

LH ECS PACK

PACK

SWITCH

PACK

SWITCHSETDOWN

TO PACK

FAN

COMP

47010¯F

44010¯F

PTF2

TO PACKTURB

MIXER

CO

ND

PACKDUCTOVERTEMPERATURESWITCH

WATERCOLLECTOR

RECIRCULATION AIR INLET

M

SECONDARYHEAT

EXCHANGER

HEATEXCHANGER

PRIMARY

TO PACK VALVE

VALVE

VALVE

FADEC ECS OFF SIGNAL

APU BLEED OFF

PACK DUCT LEAKAGE

ENGINE START

1

1

2

2

3 3

OVERTEMPERATURE

AIR CONDITIONING/PNEUMATIC

C H

CKPT RECIRC PASS CABIN

GASPER

WING 1 A/ISTAB A/ISTARTER 1

XBLEED

WING 2 A/ISTARTER 2

BLEED 1 APU BLEED BLEED 2

ATTD

AUTOCLOSED OPEN

PACK 1 PACK 2

GNDCONN

OPEN

PULL KNOB FOR MANUAL CONTROL

C H

LEAK LEAK

OPPOSITE PACK CLOSED

55 1.5 PSIG

4

4

WING A/I VALVE CLOSED (FOR RH PACK VALVE)

200

10

¯F

EM145AMM210373A.DGN

COOLING PACK SYSTEM - SCHEMATIC DIAGRAM



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PACK SYSTEM 1 - ELECTRICAL OPERATION

DC Bus 1 supplies 28 V DC to energize the pack valve 1 solenoid,allowing the pack valve 1 to open if:

− The air conditioning 1 switch on the overhead panel is pushed.

− Pack 1 shutoff relay 1 is not energized.




− Pack 1 shutoff relay 5 is energized or wing 1 anti-ice valve indica-tion relay is not energized or pack valve 2 position relay 2 is notenergized.

As soon as pack valve 1 is opened, its position switch sends a groundsignal to energize pack valve 1 position relay 1:

− To send a ground signal to allow the Digital Temperature Controller1 (DTC 1) operation.

− To allow the cockpit recirculation fan operation.

− To control the APU surge valve to close.

− To remove the signal not to allow the ram air valve opening.

Pack valve 1 position relay 2 receives a ground signal from the packvalve 1 position switch and is energized.

Pack valve 1 will operate in the high mode (high-stage solenoidenergized) when:

− Pack valve 2 position relay 2 is not energized (pack valve 2closed).

− The pack 1 set-down relay is not energized (pack 1 set-downswitch not actuated).

Pack valve 1 will operate in the normal (low) mode (high-stagesolenoid deenergized) when:

− Pack valve 2 position relay 2 is energized (pack valve 2 open) or

− The pack 1 set-down relay is energized (pack 1 set-down switchactuated).

The pack 1 set-down relay will be energized when the temperature ofthe air downstream of the ACM compressor reaches 227 ± 6oC (440± 10oF). When it occurs, the pack 1 set-down switch sends a groundsignal to energize the pack 1 set-down relay, and it is kept energizedby a ground signal that passes through its contacts when it isenergized. It deenergizes the high-stage solenoid and pack valve 1operates in the normal (low) mode.

Pack valve 1 will automatically close when:

− The pack 1 overpressure switch senses an overpressure of 55 ±1.5 psig downstream of pack valve 1. The pack 1 overpressureswitch sends a ground signal to energize pack 1 shutoff relay 3. Itis kept energized by a ground signal that passes through itscontacts. When it occurs, a ground signal is removed from DAU 1.The EICAS display shows the ″PACK 1 OVLD″ caution message.

− The pack 1 overtemperature switch senses an overtemperature of243 ± 6oC (470 ± 10oF) downstream of the ACM compressor andsends a ground signal to energize pack 1 shutoff relay 3. It is alsokept energized by a ground signal that passes through its contacts.When it occurs, a ground signal is removed from DAU 1. TheEICAS display shows the ″PACK 1 OVLD″ caution message.

− A pack duct leak occurs. It also sends a ground signal to energizepack 1 shutoff relay 3. It is also kept energized by a ground signalthat passes through its contacts.

− Pack 1 shutoff relay 4 receives a ground signal to be energizedduring engine 1 start, or during engine 1 or engine 2 start using theAPU bleed.



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− The wing 1 anti-ice valve indication relay is energized (wing 1anti-ice valve open, ice condition operation), pack valve 2 positionrelay 2 is energized (pack valve 2 open), and pack 1 shutoff relay5 is deenergized [altitude < 24,500 ft (increasing) or altitude <23,500 ft (decreasing)].

− Pack 1 shutoff relay 1 receives an ECS OFF output ground signalfrom FADEC 1A to be energized. A ground signal passes throughthe contacts of pack 1 shutoff relay 1 to keep it energized.

− Pack 1 shutoff relay 2 receives an ECS OFF output ground signalfrom FADEC 1B to be energized. A ground signal passes throughthe contacts of pack 1 shutoff relay 2 to keep it energized.

− The pack 1 duct overtemperature switch senses anovertemperature of 93 ± 6oC (200 ± 10oF) downstream of thecondenser/mixer of pack 1. The pack 1 duct overtemperature switchsends a ground signal to energize pack 1 shutoff relay 3. It is keptenergized by a ground signal that passes through its contacts.When it occurs, a ground signal is sent to DAU 1. The EICASdisplay shows the ″PACK 1 OVHT″ caution message.

When pack valve 1 closes, the pack valve 1 position switch sends aground signal to DAU 1. The EICAS display shows the ″PACK 1 VLVCLSD″ advisory message. If there is a disagreement between thevalve actual position and the selected position, the EICAS displayshows the ″PACK 1 VLV FAIL″ caution message.

The APU bleed valve relay is energized when the APU bleed valve isopened to inhibit the ECS OFF output ground signal from bothFADEC’s 1A and 1B.

The figure ″COOLING PACK SYSTEM - PACK VALVE 1 - ELECTRI-CAL SCHEMATIC DIAGRAM″ shows the operation of pack valve 1.



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CB0229

2 1

A

C

B

PACK 1

5

DC BUS 1

WT0003

S7163

C2

B1

B2

A1

A2

D3

C3

B3

A3

4 98

5 6 7

D1

D2

C1

DC

DC

DC

DC

ON

OFF

OVERHEAD PANEL

PACK VALVE 1 S0110 PACK 1 OVERTEMP SW

P0549

R

J5

P0551

R

J5

-191 -191

K0071

XK0071

C1

C3C2

X2

X1

XK0261

A1

A3A2

B1

B3B2

X1

X2

K0261

K0260

K0183

XK0319

A1

A3A2

B1

B3B2

X1

X2

K0319

XK0187

A1

A3A2

B1

B3B2

C1

C3C2

D1

D3D2

X1

X2

K0187

XK0198

A1

A3A2

B1

B3B2

X1

X2

K0198

K0558

P0456

A

B

C

DC

P0454

B

A

C

DC

S0250 -191

49-60-50

P

D

E

F

B

A

C

GROUND WHEN ENG1

STARTS OR DURING

ENG1/ENG2 START

USING APU BLEED

DC

36-12-50

ENRGZ WHENAPU BLEED VALVE

PACK 1 SHUTOFF

PACK 1 SHUTOFFPACK 1 SHUTOFF

PACK 1 SHUTOFF

PACK VALVE 1POSITION

DC

DC

DC

PACK 1 OVERPRESSURE SW

PACK OVERPRESS 1

PACK VALVE 1 POS

PACK VALVE 1 CMD

CLOSED

NOT CLOSED

SOV

SOLENOID

HIGH STAGE

SOLENOID

DAU 1

S0252

-191

21-24-50

21-25-50

XK0260

A1

A3A2

B1

B3B2

X1

X2

PACK 1 SET DOWN SW

XK0183

A1

A3A2

B1

B3B2

X1

X2

21-61-50

DC

J1019

A-50

A-1

A-33

A-34

A-35

P1233

A

B

C

S0277

-191

P1038

D

ELEC COMPARTMENTPUSH BUTTONS DIM

(33-12-53)-113

OUTPUT 0-5VDC

225ETC - AIR CONDITIONING/PNEUMATIC

225DTC - CKT BKR PANEL

21- 21-

33-

FROM PACKDUCT LEAK

(31-41-50)-123

PACK OVERTEMP 1

DUCT OVERTEMP 1

232 C

ECS OFF OUTPUT

ECS OFF OUTPUT

FADEC 1A FADEC 1B(76-12-50)-271 (76-12-50)-271

85 C

DC

216 C

SH

SH

PACK 1 DUCT OVERTEMP SW

ENERGIZE TO

ALLOW OPENING

IS NOT CLOSED

COCKPIT TEMP CONTTO ENERGIZE DTC1

CABIN TEMP CONTTO ENERGIZE TCM

TO ALLOW

APU SURGEVALVE

CLOSE CMD

TO ALLOW DTC1OPERATION

COCKPIT RECIRCFAN OPERATION

TO ALLOW RAMAIR VALVEOPENING

WING-TO-FUS FAIR FWD PNL WING-TO-FUS FAIR FWD PNL

REAR ELEK COMPT REAR ELEK COMPT

WING-TO-FUS FAIR FWD PNL WING-TO-FUS FAIR FWD PNLCOCKPIT FLOOR

WING-TO-FUS FAIR FWD PNL

223ELW - LEFT RELAY SUPPORT

J1

APU BLEED VALVE

55 1.5 PSIG

-223CR0070

21-51-52

SH

SH

243 5 C

44 PSIG

36-

AIR COND 1 SW

P1023

23

P1022

23

J7187

50

XK0435

C1

C3

C2

X2

X1

K0435

K0529 XK0529

A1

A3

A2

B1

B3

B2X1

X2

/

DC

PACK 1 SHUTOFF

/

ENERG WHEN

IS NOT CLSD

WGI A/I VLV

30-10-50

34-15-50 - 213ADC 1

FWD ELEK COMPT FWD ELEK COMPTADC 2

34-15-50 - 214MAINTENANCE PANEL - 223

L AFT CONSOLE

PACK VALVE 2 POS RELAY 2

21-51-51 21-51-51

- 224ERW

XK0557

A1

A3A2

X1

X2

K0557

PACK VALVE 1 POS RELAY 2- 223ELW

>24500 FT

= GROUND

>24500 FT

= GROUND

ALT TRIP TEST

L RELAY SUPPORT - (I5)

RELAY1 - (C13)

RELAY 4 - (C19)RELAY 3 - (C15)

RELAY 2 - (C18)

RELAY 1 - (C17)

RELAY - (C11)

21-51-51

RLY 5 - (D22)

WING1 A/I VLV

IND RLY - (I23)

XK0558

A1

A3A2

B1

B3B2

X1

X2

R RELAY SUPPORT - (I5)

PACK 1 SET RELAYRELAY - (C16)

2285

L0181

CR0303

CR0316

61-50 62-50

12-53

5

4

1

12-50

1 A/C WITH PUSHBUTTON−LIGHTING TEST−SWITCH.

4 52 3

3 P0944

2

6C

93

6C

227

A/C S/N 145 THRU 188PRE−MOD SB 145−21−0028

A/C S/N 189, AND ON, ORPOST−MOD SB 145−21−0028



6

PRE−MOD SB 145−21−00516

EM145AMM210272D.DGN

COOLING PACK SYSTEM - PACK VALVE 1 - ELECTRICAL SCHEMATIC DIAGRAM



Oct 27/06

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230

PACK SYSTEM 2 - ELECTRICAL OPERATION

DC Bus 2 supplies 28 V DC to energize the pack valve 2 solenoid,allowing the pack valve 2 to open if:

− The air conditioning 2 switch on the overhead panel is pushed.





As soon as pack valve 2 is opened, its position switch sends a groundsignal to energize pack valve 2 position relay 1:

− To send a ground signal to allow the Digital Temperature Controller2 (DTC 2) operation.

− To allow the cabin recirculation fan operation.

− To control the APU surge valve to close.

− To remove the signal not to allow the ram air valve opening.

Pack valve 2 position relay 2 receives a ground signal from the packvalve 2 position switch and is energized.

Pack valve 2 will operate in the high mode (high-stage solenoidenergized) when:

− Pack valve 1 position relay 2 is not energized (pack valve 1closed).

− The pack 2 set-down relay is not energized (pack 2 set-downswitch not actuated).

− Wing 1 anti-ice valve indication relay is not energized (wing 1anti-ice valve in the closed position).

Pack valve 2 will operate in the normal (low) mode (high-stagesolenoid deenergized) when:

− Pack valve 1 position relay 2 is energized (pack valve 1 open) or

− The pack 2 set-down relay is energized (pack 2 set-down switchactuated) or

− Wing 1 anti-ice valve indication relay is energized (wing 1 anti-icevalve in the open position).

The pack 2 set-down relay will be energized when the temperature ofthe air downstream of the ACM compressor reaches 227 ± 6oC (440± 10oF). When it occurs, the pack 2 set-down switch sends a groundsignal to energize the pack 2 set-down relay, and it is kept energizedby a ground signal that passes through its contacts when it isenergized. It deenergizes the high-stage solenoid and pack valve 2operates in the normal (low) mode.

Pack valve 2 will automatically close when:

− The pack 2 overpressure switch senses an overpressure of 55 ±1.5 psig downstream of pack valve 2. The pack 2 overpressureswitch sends a ground signal to energize pack 2 shutoff relay 3. Itis kept energized by a ground signal that passes through itscontacts. When it occurs, a ground signal is removed from DAU 1.The EICAS display shows the ″PACK 2 OVLD″ caution message.

− The pack 2 overtemperature switch senses an overtemperature of243 ± 6oC (470 ± 10oF) downstream of the ACM compressor andsends a ground signal to energize pack 2 shutoff relay 3. It is alsokept energized by a ground signal that passes through its contacts.When it occurs, a ground signal is removed from DAU 1. TheEICAS display shows the ″PACK 2 OVLD″ caution message.

− A pack duct leak occurs. It also sends a ground signal to energizepack 2 shutoff relay 3. It is also kept energized by a ground signalthat passes through its contacts.

− Pack 2 shutoff relay 4 receives a ground signal to be energizedduring engine 2 start, or during engine 1 or engine 2 start using theAPU bleed.



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Mar 29/01

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− Pack 2 shutoff relay 1 receives an ECS OFF output ground signalfrom FADEC 2A to be energized. A ground signal passes throughthe contacts of pack 2 shutoff relay 1 to keep it energized.

− Pack 2 shutoff relay 2 receives an ECS OFF output ground signalfrom FADEC 2B to be energized. A ground signal passes throughthe contacts of pack 2 shutoff relay 2 to keep it energized.

− The pack 2 duct overtemperature switch senses anovertemperature of 93 ± 6oC (200 ± 10oF) downstream of thecondenser/mixer of pack 2. The pack 2 duct overtemperature switchsends a ground signal to energize pack 2 shutoff relay 3. It is keptenergized by a ground signal that passes through its contacts.When it occurs, a ground signal is sent to DAU 1. The EICASdisplay shows the ″PACK 2 OVHT″ caution message.

When pack valve 2 closes, the pack valve 2 position switch sends aground signal to DAU 1. The EICAS display shows the ″PACK 2 VLVCLSD″ advisory message. If there is a disagreement between thevalve actual position and the selected position, the EICAS displayshows the ″PACK 2 VLV FAIL″ caution message.

The APU bleed valve relay is energized when the APU bleed valve isopened and the cross bleed relay is energized when the cross bleedvalve is opened. When this occurs, the ECS OFF output groundsignals from both FADEC’s 2A and 2B are inhibited.

The figure ″COOLING PACK SYSTEM - PACK VALVE 2 - ELECTRI-CAL SCHEMATIC DIAGRAM″ shows the operation of pack valve 2.

The figure ″COOLING SYSTEM - DUCT LEAK SENSOR DIAGRAM″shows the operation of the sensors.



Mar 29/01

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230

CB0228

2 1

P0945

A

C

B

PACK 2

5

DC BUS 2

WT0004

S7164

C2

B1

B2

A1

A2

D3

C3

B3

A3

4 98

5 6 7

D1

D2

C1

DC

DC

DC

DC

ON

OFF

OVERHEAD PANEL

L PACK VALVE 2 S0111 PACK 2 OVERTEMP SW

P0550

R

J5

P0552

R

J5

-191 -191

K0071

XK0071

D1

D3D2

X2

X1

XK0263

A1

A3A2

B1

B3B2

X1

X2

K0263

K0262

K0184

XK0320

A1

A3A2

B1

B3B2

X1

X2

K0320

XK0188

A1

A3A2

B1

B3B2

C1

C3C2

D1

D3D2

X1

X2

K0188

XK0199

A1

A3A2

B1

B3B2

X1

X2

K0199

XK0557

A1

A3A2

X1

K0557

P0457

A

B

C

DC

P0455

B

A

C

DC

S0251 -191

49-60-50

P

D

E

F

B

A

C

GROUND WHEN ENG2

STARTS OR DURING

ENG1/ENG2 START

USING APU BLEED

DC

36-12-50

ENRGZ WHENAPU BLEED VALVE

PACK 2 SHUTOFF

PACK 2 SHUTOFF

PACK 2 SHUTOFF PACK 2 SHUTOFFSET DOWN

DC

DC

DC

PACK 2 OVERPRESSURE SW

PACK OVERPRESS 2

PACK VALVE 2 POS

PACK VALVE 2 CMD

CLOSED

NOT CLOSED

SOV

SOLENOID

HIGH STAGE

SOLENOID

DAU 1

S0253

-191

21-25-50

XK0262

A1

A3A2

B1

B3B2

X1

X2

PACK 2 SET DOWN SW

XK0184

A1

A3A2

B1

B3B2

X1

X2

21-62-50

J1021

A-50

A-33

A-34

A-35

A-36

P1234

A

B

C

S0278

-191

P1038

D

ELEC COMPARTMENTPUSH BUTTONS DIM

(33-12-53)-113

OUTPUT 0-5VDC

225ETC - AIR CONDITIONING/PNEUMATIC

225DTC - CKT BKR PANEL

21- 21-

33-

FROM PACKDUCT LEAK

PACK 2

(31-41-50)-123

PACK OVERTEMP 2

DUCT OVERTEMP 2

232 C

ECS OFF OUTPUT

ECS OFF OUTPUT

FADEC 2A FADEC 2B(76-12-51)-272 (76-12-51)-272

85 C

DC

216 C

SH

SH

PACK 2 DUCT OVERTEMP SW

CABIN TEMP CONTROLTO ENERGIZE DTC2

COCKPIT TEMP CONTROLTO ENERGIZE TCM

IS NOT CLOSED

21-24-51TO ALL0W

CABIN RECIRC FAN OPERATION

APU SURGEVALVE

CLOSE CMD

TO ALLOW RAMAIR VALVEOPENING

ENERGIZE TO

ALLOW OPENING

WING-TO-FUS FAIR FWD PNL WING-TO-FUS FAIR FWD PNL

REAR ELEK COMPT REAR ELEK COMPT

WING-TO-FUS FAIR FWD PNL WING-TO-FUS FAIR FWD PNLCOCKPIT FLOOR

WING-TO-FUS FAIR FWD PNL

J2

55 1.5 PSIG

APU BLEED VALVE

223ELW-LEFT RELAY SUPPORT

224ERW - RIGHT RELAY SUPPORT

-224

CR0071

21-51-52

SH

SH

243 5 C

44 PSIG

36-

AIR COND 2 SW

XK0171

A1

A3A2

X2

X1

K0171

36-11-52

PACK VALVE 1 POS RLY 2

-223ELW

21-51-50

K0558

21-51-50

-224ERWPACK VALVE 2 POS RLY 1

-224ERWPACK VALVE 2 POS RLY 2

XK0558

A1

A3A2

B1

B3B2

X1

X2

RELAY - (C12)

R RELAY SUPPORT - (C19)

RELAY 4 - (C15)RELAY 3 - (C10)

RELAY 2 - (C14)

RELAY 1 - (C13)

CROSS BLEED RLY - (C8)

RELAY - (C11)

L RELAY SUPPORT - (I5)

R RELAY SUPPORT - (I5)

K0435

-223ELWWING A/I VALVES IND RLYL RLY SUPPORT - (I23)

2284

0182

XK0435

D3

D1

X2X1

D2

CR0302

CR0315

62-50 61-50

12-53

1

5

12-50

4

TO ALLOW DTC2

OPERATION

30-10-50 30-10-50

1

A/C WITH PUSHBUTTON−LIGHTING TEST−SWITCH.

X2

3

2

4 52 3

6C

93

6C

227





PRE−MOD SB 145−21−00516

6

EM145AMM210273D.DGN

COOLING PACK SYSTEM - PACK VALVE 2 - ELECTRICAL SCHEMATIC DIAGRAM



Oct 27/06

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sds1

230



EFFECTIVITY: ALL

21-51-00

Mar 29/01

(45-45-50) -124 CMC COCKPIT FLOOR

J1423

A-A

1

B-A

1

PA

CK

DU

CT

LE

AK

1

PA

CK

DU

CT

LE

AK

2

LH P

AC

K D

UC

T L

EA

KS

0169

RH

PA

CK

DU

CT

LE

AK

S01

79-1

91

-191

DC

DC

CR0070-223 CR0071-223

(92

˚C)

197

˚F

197

˚F(9

2 ˚C

)

21-51-51TO SHUT PACK

VALVE 2 OFF

21-51-50TO SHUT PACK

VALVE 1 OFF

145AMM210101.MCE B

COOLING SYSTEM - DUCT LEAK SENSOR DIAGRAM



Mar 29/01

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sds1

230



EFFECTIVITY: ALL

21-51-00

Mar 29/01

sds1230-21-51-00

Documents

refrigeration pack

pack valves

pack ducts

pack overtemperature

valve shaft

butterfly valve

pack overpressure switch

pack setdown switch