LIGHTS Switch
AUTO – the airstair tread lights illuminate automatically upon airstair extension
and extinguish upon retraction.
ON – illuminates the airstair tread lights.

Normal Control Switches
Note: AC and DC electrical power must be available on airplane.
RETRACT – retracts the airstair. The handrail extensions must be stowed prior to
retracting the airstair.
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Airplane General, Emergency Equipment, Doors, Windows -Controls and Indicators 737 Flight Crew Operations Manual

EXTEND – extends the airstair.

STANDBY Control Switch Note: Switch must be held in while using EXTEND or RETRACT. Battery switch must be ON. Extend – extends the airstair. Retract – retracts the airstair.
CAUTION: Use of standby bypasses all safety circuits. Airstair handrail extensions must be stowed or substantial damage could result.

STAIRS Operating (OPER) Light
Illuminated (amber) – indicates the airstair is in transit.

AIRSTAIRS Control Switch
EXTEND – extends the airstair. RETRACT – retracts the airstair.

POWER Switch
(spring-loaded to NORMAL)
NORMAL – requires both AC and DC power.
STANDBY – requires DC power.

Copyright . The Boeing Company. See title page for details.
1.30.26  June 1, 2005

Airplane General, Emergency Equipment, Doors, Windows -Controls and Indicators
Water System Controls

Water Quantity Indicator
Indicates quantity of water in reservoir.

Water System Service Panel
Fill Fitting
Used to fill tank.

Fill and Overflow Valve Handle
Open - enables filling or gravity draining water tank.
Closed - normal position.

Tank Drain Valve Handle
Open -drains water from tank.
Closed - normal position.

Access Panel
Cannot be closed unless the Fill and Overflow Valve and Tank Drain Valve Handles are in the closed position.
Copyright . The Boeing Company. See title page for details.
Airplane General, Emergency Equipment, Doors, Windows -Controls and Indicators 737 Flight Crew Operations Manual

Lavatory Controls
YA613 - YC413, YK101 - YK104

Water Heater Switch
On – activates the water heater.

Water Heater Light
Illuminated - heater operating.

Temperature Control Switch
Water Supply Selector Valve
SUPPLY ON – provides water to lavatory sink faucets and water heater (normal
position).
FAUCET ONLY– water is supplied to faucet only.
OFF – shuts off water to lavatory sink faucets and water heater.
TOILET ONLY– water is supplied to toilet only.

Drain Valve
Located in the forward lavatory.
Copyright . The Boeing Company. See title page for details.
1.30.28  June 1, 2005

Airplane General, Emergency Equipment, Doors, Windows -Controls and Indicators
737 Flight Crew Operations Manual
YD651 - YD655

LAVATORY SINK CABINET

Water Heater Switch
On – activates the water heater.

Water Heater Light
Illuminated - heater operating.

Temperature Control Switch
Water Supply Selector Valve
Each lavatory has a Water Supply Selector Valve. The Water Supply Selector
Valve has four positions, and is located in the cabinet below the sink. SUPPLY ON – Normal operating position. When the water system is depressurized, all lavatories except “A” will drain. In this lavatory, the drain valve must be opened to drain the lavatory
FAUCET ONLY – In this position, water is supplied to the faucet, but not to the toilet
Copyright . The Boeing Company. See title page for details.
Airplane General, Emergency Equipment, Doors, Windows -Controls and Indicators 737 Flight Crew Operations Manual

TOILET ONLY – In this position, water is supplied to the toilet, but not to the faucet OFF – No water is supplied to the lavatory.

Drain Valve Handle (red)
Located in the forward lavatory only.
Copyright . The Boeing Company. See title page for details.
1.30.30  June 1, 2005

737 Flight Crew Operations Manual

Introduction
YA613 - YC154, YD651 - YK104
This chapter describes miscellaneous airplane systems, including:

.
lighting systems . emergency egress
. oxygen systems . flight deck seats

.
fire extinguishers .galleys

.
emergency equipment . water systems

.
doors and windows . lavatories

.
cargo compartments

YC411, YC413
　
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