Boeing 737 - 600/700/800/900. Operations Manual (1997 year)

Air Systems -

Table of Contents

Boeing 737 Operations Manual

Flight Deck

2.30.4

Passenger Cabin

2.30.4

Recirculation Fan

2.30.4

Equipment Cooling

2.30.4

Forward Cargo Compartment

2.30.5

Conditioned Air Source Connection

2.30.5

Air Conditioning Distribution Schematic

2.30.6

Air Conditioning System Description

2.31.1

Introduction

2.31.1

Air Conditioning Pack

2.31.1

Airflow Control

2.31.1

Ram Air System

2.31.2

Cooling Cycle

2.31.2

Pack Temperature Control

2.31.2

Air Conditioning Pack Schematic

2.31.3

Zone Temperature Control

2.31.4

Zone Temperature Control Modes

2.31.4

Unbalanced Pack Temperature Control Mode

2.31.4

Standby Pack Average Temperature

2.31.5

Fixed Cabin Temperature

2.31.5

Air Conditioning Distribution

2.31.5

Flight Deck

2.31.5

Passenger Cabin

2.31.5

Recirculation Fan

2.31.6

Equipment Cooling

2.31.6

Forward Cargo Compartment

2.31.6

Conditioned Air Source Connection

2.31.6

Air Conditioning Distribution Schematic

2.31.7

Pressurization System Description

2.40.1

Introduction

2.40.1

Pressure Relief Valves

2.40.1

Cabin Pressure Controller

2.40.1

2.TOC.0.2

Air Systems -

Table of Contents

Boeing 737 Operations Manual

Cabin Pressure Control System Schematic

2.40.2

Pressurization Outflow

2.40.2

Outflow Valve

2.40.3

Overboard Exhaust Valve

2.40.3

Pressurization Outflow Schematic

2.40.4

Auto Mode Operation

2.40.5

High Altitude Landing

2.40.6

Flight Path Events - Auto Mode

2.40.7

Manual Mode Operation

2.40.8

2.TOC.0.3

Boeing 737 Operations Manual

Air Systems

Chapter 2

Controls and Indicators

Section 10

Bleed Air Controls and Indicators

[737 - 600/700]

DUAL

RAM DOOR

BLEED

FULL OPEN

RECIRC FAN

OFF

AUTO

DUCT

OVHT

PRESS

PSI

TEST

L PACK

R PACK

ISOLATION

OFF

VALVE

AUTO

HIGH

AUTO

WING

PACK

WING

ANTI

TRIP OFF

OPEN

TRIP OFF

ANTI

ICE

WING-BODY

TRIP

WING-BODY

OVERHEAT

BLEED

TRIP OFF

RESET

OFF

APU

BLEED

FORWARD OVERHEAD PANEL

2.10.1

Air Systems -

Controls and Indicators

Boeing 737 Operations Manual

[737 - 800/900]

DUAL

RAM DOOR

BLEED

FULL OPEN

L RECIRC FAN

R RECIRC FAN

OFF

AUTO

DUCT

OVHT

PRESS

PSI

TEST

L PACK

R PACK

ISOLATION

OFF

VALVE

AUTO

HIGH

AUTO

WING

ANTI

PACK

OPEN

PACK

ANTI

ICE

WING-BODY

TRIP

WING-BODY

OVERHEAT

BLEED

TRIP OFF

RESET

OFF

APU

BLEED

FORWARD OVERHEAD PANEL

DUAL BLEED Light

Illuminated (amber) - APU bleed air valve open and engine No. 1 BLEED air

switch ON, or engine No. 2 BLEED air switch ON, APU bleed air valve and

isolation valve open.

ISOLATION VALVE Switch

CLOSE - closes isolation valve.

AUTO -

• closes isolation valve if both engine BLEED air switches are ON and both

air conditioning PACK switches are AUTO or HIGH

• opens isolation valve automatically if either engine BLEED air or air

conditioning PACK switch positioned OFF.

OPEN - opens isolation valve.

2.10.2

Air Systems -

Controls and Indicators

Boeing 737 Operations Manual

WING-BODY OVERHEAT Light

Illuminated (amber) -

• left light indicates overheat from bleed air duct leak in left engine strut,

left inboard wing leading edge, left air conditioning bay, keel beam or

APU bleed air duct

• right light indicates overheat from bleed air duct leak in right engine strut,

right inboard wing leading edge or right air conditioning bay.

Engine BLEED Air Switches

OFF - closes engine bleed air valve.

ON - opens engine bleed air valve when engines are operating.

APU BLEED Air Switch

OFF - closes APU bleed air valve.

ON - opens APU bleed air valve when APU is operating.

Bleed Air DUCT PRESSURE Indicator

Indicates pressure in L and R (left and right) bleed air ducts.

Wing-Body Overheat (OVHT) TEST Switch

Push -

• tests wing-body overheat detector circuits

• illuminates both WING-BODY OVERHEAT lights.

BLEED TRIP OFF Light

Illuminated (amber) - excessive engine bleed air temperature or pressure

• related engine bleed air valve closes automatically

• requires reset.

TRIP RESET Switch

[737 - 600/700]

Push (if fault condition is corrected) -

• resets BLEED TRIP OFF, PACK TRIP OFF and DUCT OVERHEAT

lights

• lights remain illuminated until reset.

2.10.3

Air Systems -

Controls and Indicators

Boeing 737 Operations Manual

TRIP RESET Switch

[737 - 800/900]

Push (if fault condition is corrected) -

• resets BLEED TRIP OFF, PACK and ZONE TEMP lights

• related engine bleed valve opens, or related pack valve opens, or related

air mix valve opens

• lights remain illuminated until reset.

2.10.4

Air Systems -

Controls and Indicators

Boeing 737 Operations Manual

Air Conditioning Controls and Indicators

[737 - 600/700 and Air Temperature Indicator in degrees C]]

CONT CABIN

AIR TEMP

PASS CABIN

SUPPLY

PASS

DUCT

CABIN

AIR MIX

VALVE

TEMP

DUCT

OVERHEAT

100

AUTO

COOL

WARM

COOL

WARM

COOL

WARM

COOL

WARM

MANUAL

DUAL

RAM DOOR

BLEED

FULL OPEN

RECIRC FAN

OFF

AUTO

DUCT

OVHT

PRESS

PSI

TEST

L PACK

ISOLATION

R PACK

OFF

VALVE

AUTO

HIGH

AUTO

WING

PACK

WING

ANTI

TRIP OFF

OPEN

TRIP OFF

ANTI

ICE

WING-BODY

TRIP

WING-BODY

OVERHEAT

BLEED

TRIP OFF

RESET

OFF

APU

BLEED

FORWARD OVERHEAD PANEL

AIR Temperature (TEMP) Source Selector

SUPPLY DUCT - selects main distribution supply duct

sensor

for

TEMP

indicator.

2.10.5

Air Systems -

Controls and Indicators

Boeing 737 Operations Manual

PASS CABIN - selects passenger cabin sensor for TEMP indicator.

DUCT OVERHEAT Light

Illuminated (amber) -

• bleed air temperature in related duct exceeds limit

• air mix valves drive full cold

• requires reset.

Control (CONT) CABIN and Passenger (PASS) CABIN Temperature

Selector

AUTO - automatic temperature controller controls passenger cabin or flight deck

temperature as selected.

MANUAL - air mix valves controlled manually. Automatic temperature

controller bypassed.

RAM DOOR FULL OPEN Light

Illuminated (blue) - indicates ram door in full open position.

Air Conditioning PACK Switch

OFF - pack signalled OFF.

AUTO -

• with both packs operating, each pack regulates to low flow

• with one pack operating, operating pack regulates to high flow in flight

with flaps up

• when operating one pack from APU (both engine BLEED air switches

OFF), regulates to high flow.

HIGH -

• pack regulates to high flow

• provides maximum flow rate on ground with APU BLEED air switch ON.

AIR MIX VALVE Indicator

Indicates position of air mix valves:

• controlled automatically with related temperature selector in AUTO

• controlled manually with related temperature selector in MANUAL.

Air Temperature (TEMP) Indicator

Indicates temperature at location selected with AIR TEMP source selector.

2.10.6

Air Systems -

Controls and Indicators

Boeing 737 Operations Manual

Recirculation (RECIRC) FAN Switch

OFF - fan signalled off.

AUTO - fan signalled on except when both packs operating with either PACK

switch in HIGH.

PACK TRIP OFF Light

Illuminated (amber) -

• indicates pack temperature has exceeded limits

• related pack valve automatically closes and mix valves drive full cold

• requires reset.

TRIP RESET Switch

Push (if fault condition is corrected) -

• resets BLEED TRIP OFF, PACK TRIP OFF and DUCT OVERHEAT

lights

• related engine bleed air valves open, or related pack valves open, or

related air mix valves open

• lights remain illuminated until reset.

October 15, 2001

2.10.7

Air Systems -

Controls and Indicators

Boeing 737 Operations Manual

[737 - 800/900 and Air Temperature Indicator in degrees F]

AIR TEMP

PASS

CAB

120MP1.

FWD

AFT

200

CONT

TRIM AIR

CAB

OFF

ZONE

TEMP a

CONT CAB

FWD CAB

AFT CAB

AUTO

OFF

DUAL

RAM DOOR

BLEED

FULL OPEN

L RECIRC FAN

R RECIRC FAN

OFF

AUTO

DUCT

OVHT

PRESS

PSI

TEST

L PACK

R PACK

ISOLATION

OFF

VALVE

OFF

AUTO

HIGH

AUTO

WING

PACK

OPEN

PACK

ANTI

ICE

WING-BODY

TRIP

WING-BODY

OVERHEAT

BLEED

TRIP OFF

RESET

OFF

APU

BLEED

FORWARD OVERHEAD PANEL

Air Temperature (TEMP) Indicator

Indicates temperature at location selected with AIR TEMP source selector.

2.10.8

Air Systems -

Controls and Indicators

Boeing 737 Operations Manual

ZONE TEMP Lights

Illuminated (amber) -

• CONT CAB indicates a duct temperature overheat or failure of the flight

deck primary and standby temperature control

• FWD CAB or AFT CAB indicates duct temperature overheat.

During Master Caution light recall:

• CONT CAB indicates failure of the flight deck primary or standby

temperature control

• either FWD CAB or AFT CAB indicates failure of the associated zone

temperature control

• lights will extinguish when Master Caution is reset.

Temperature Selector

AUTO - provides automatic temperature control for the associated zones.

Rotating the control toward C (cool) or W (warm) manually sets the desired

temperature.

OFF - closes the associated trim air modulating valve.

RAM DOOR FULL OPEN Light

Illuminated (blue) - indicates ram door in full open position.

Air Conditioning PACK Switch

OFF - pack signalled OFF.

AUTO -

• with both packs operating, each pack regulates to low flow

• with one pack operating, operating pack regulates to high flow in flight

with flaps up

• when operating one pack from APU (both engine BLEED air switches

OFF), regulates to high flow.

HIGH -

• pack regulates to high flow

• provides maximum flow rate on ground with APU BLEED air switch ON.

AIR Temperature (TEMP) Source Selector

SUPPLY DUCT - selects appropriate zone supply duct temperature

PASS CAB - selects forward or aft passenger cabin temperature

PACK - selects left or right pack temperatures.

2.10.9

Air Systems -

Controls and Indicators

Boeing 737 Operations Manual

TRIM AIR Switch

ON - trim air pressure regulating and shutoff valve signaled open.

OFF - trim air pressure regulating and shutoff valve signaled closed.

Recirculation (RECIRC) FAN Switches

OFF - fan signalled off.

AUTO -

• in-flight -

• the left recirculation fan operates if both packs are operating unless

either PACK switch is in HIGH

• the right recirculation fan operates if both packs are operating unless

both PACK switches are in HIGH.

• on the ground -

• the left recirculation fan operates unless both PACK switches are in

HIGH

• the right recirculation fan operates even if both PACK switches are in

HIGH.

PACK Light

Illuminated (amber) -

• indicates pack trip off or failure of both primary and standby pack

controls

• during Master Caution recall, indicates failure of either primary or

standby pack control. Extinguishes when Master Caution is reset

TRIP RESET Switch

Push (if fault condition is corrected) -

• resets BLEED TRIP OFF, PACK and ZONE TEMP lights

• lights remain illuminated until reset.

2.10.10

Air Systems -

Controls and Indicators

Boeing 737 Operations Manual

Equipment Cooling Panel

EQUIP COOLING

SUPPLY

EXHAUST

NORM

ALTN

OFF

FORWARD OVERHEAD PANEL

Equipment (EQUIP) COOLING SUPPLY Switch

NORM - normal cooling supply fan activated.

ALTN - alternate cooling supply fan activated.

Equipment Cooling Supply OFF Light

Illuminated (amber) - no airflow from selected cooling supply fan.

Equipment (EQUIP) COOLING EXHAUST Switch

NORM - normal cooling exhaust fan activated.

ALTN - alternate cooling exhaust fan activated.

Equipment Cooling Exhaust OFF Light

Illuminated (amber) - no airflow from selected cooling exhaust fan.

2.10.11

Air Systems -

Controls and Indicators

Boeing 737 Operations Manual

Cabin Altitude Panel

[Option - High Altitude Landing switch]

ALT

HORN

CUTOUT

CABIN

ALT

X 1000 FEET

HIGH

ALT LDG

PRESS DIFF

LIMIT:TAKE-

INOP

OFF & LDG

.125 PSI

FORWARD OVERHEAD PANEL

CABIN Altimeter (ALT)/Differential Pressure (DIFF PRESS)

Indicator

Inner Scale - indicates cabin altitude in feet.

Outer Scale - indicates differential pressure between cabin and ambient in psi.

CABIN Rate of CLIMB Indicator

Indicates cabin rate of climb or descent in feet per minute.

Altitude (ALT) HORN CUTOUT Switch

Push -

• cuts out intermittent cabin altitude warning horn

• altitude warning horn sounds when cabin reaches 10,000 feet altitude.

2.10.12

Air Systems -

Controls and Indicators

Boeing 737 Operations Manual

High Altitude Landing Switch

[Option - High Altitude Landing switch]

Off - (ON not visible)

• reprograms cabin pressurization from high altitude to normal operation

• extinguishes INOP light

High Altitude Landing INOP Light

[Option - High Altitude Landing switch]

Illuminated (amber) - indicates high altitude landing system fault.

Cabin Pressurization Panel

AUTO

OFF SCHED

ALTN

MANUAL

FAIL

DESCENT

AUTO

MANUAL

FLT ALT

LAND ALT

ALTN

AUTO

MAN

CAB ALT

LAND ALT

2000

4000

6000

8000

FLT ALT

<FL160 FL220 FL260 FL320 FL410

FORWARD OVERHEAD PANEL

AUTO FAIL Light

Illuminated (amber) - automatic pressurization system failure detected:

• indicates a single controller failure when ALTN light is also illuminated

• indicates a dual controller failure when illuminated alone.

2.10.13

Air Systems -

Controls and Indicators

Boeing 737 Operations Manual

OFF Schedule (SCHED) DESCENT Light

Illuminated (amber) - airplane descended before reaching the planned cruise

altitude set in the FLT ALT indicator.

Flight Altitude (FLT ALT) Indicator

• indicates selected cruise altitude

• set before takeoff.

Flight Altitude Selector

Rotate - set planned cruise altitude.(-1,000 ft. to 42,000 ft. in 500 ft. increments).

Landing Altitude (LAND ALT) Indicator

• indicates altitude of intended landing field

• set before takeoff.

Landing Altitude Selector

Rotate - select planned landing field altitude. (-1,000 ft. to 14,000 ft. in 50 ft.

increments).

MANUAL Light

Illuminated (green) - pressurization system operating in the manual mode.

Alternate (ALTN) Light

Illuminated (green) - pressurization system operating in the alternate automatic

mode:

• Illumination of both ALTN and AUTO FAIL lights indicates a single

controller failure and automatic transfer to ALTN mode

• pressurization mode selector in ALTN position.

Outflow VALVE Position Indicator

• indicates position of outflow valve

• operates in all modes.

Outflow Valve Switch (spring-loaded to center)

CLOSE - closes outflow valve electrically with pressurization mode selector in

MAN position.

OPEN - opens outflow valve electrically with pressurization mode selector in

MAN position.

2.10.14

Air Systems -

Controls and Indicators

Boeing 737 Operations Manual

Pressurization Mode Selector

AUTO - pressurization system controlled automatically.

ALTN - pressurization system controlled automatically using ALTN controller.

MAN -

• pressurization system controlled manually by outflow valve switch

• both auto controllers bypassed.

Cabin /Flight Altitude (CAB ALT)(FLT ALT) Placard

Used to determine setting for cabin altitude when operating in manual mode.

2.10.15

Boeing 737 Operations Manual

Air Systems

Chapter 2

Bleed Air System Description

Section 20

Introduction

Air for the bleed air system can be supplied by the engines, APU, or an external

air cart/source. The APU or external cart supplies air to the bleed air duct prior to

engine start. After engine start, air for the bleed air system is normally supplied by

the engines.

The following systems rely on the bleed air system for operation:

• Air conditioning/pressurization

• Wing and engine thermal anti-icing

• Engine starting

• Hydraulic reservoirs pressurization

• Water tank pressurization

[Option - Aspirated TAT]

• Aspirated TAT probe

Switches on the air conditioning panel operate the APU and engine bleed air

supply system.

Engine Bleed System Supply

Engine bleed air is obtained from the 5th and 9th stages of the compressor section.

When 5th stage low pressure bleed air is insufficient for the bleed air system

requirements, the high stage valve modulates open to maintain adequate bleed air

pressure. During takeoff, climb, and most cruise conditions, low pressure bleed air

from the 5th stage is adequate and the high stage valve remains closed.

Engine Bleed Air Valves

The engine bleed air valve acts as a pressure regulator and shutoff valve. With the

engine bleed air switch ON, the valve is DC activated and pressure operated. The

valve maintains proper system operating pressure and reduces bleed air outflow in

response to high bleed air temperature.

Bleed Trip Sensors

Bleed trip sensors illuminate the respective BLEED TRIP OFF light when engine

bleed air temperature or pressure exceeds a predetermined limit. The respective

engine bleed air valve closes automatically.

2.20.1

Boeing 737 - 600/700/800/900. Operations Manual (1997 year) - page 26