Hydraulics -Controls and Indicators
Flight Control Panel (after Rudder System Enhancement Program (RSEP) modification)
FORWARD OVERHEAD PANEL
FLIGHT CONTROL Switches
STBY RUD – activates standby pump, opens standby rudder shutoff valve to
pressurize standby rudder power control unit, and illuminates amber STBY RUD
ON light.
OFF – closes flight control shutoff valve isolating ailerons, elevators and rudder
from associated hydraulic system pressure.
ON (guarded position) – normal operating position.
Hydraulics -Controls and Indicators 737 Operations Manual
Flight Control LOW PRESSURE Lights
Illuminated (amber) –
.
indicates low hydraulic system (A or B) pressure to ailerons, elevator and
rudder
.
deactivated when associated FLT CONTROL switch is positioned to
STBY RUD and standby rudder shutoff valve opens
.
the A system light indicates A system pressure is low when full RPR
pressure is commanded.
Note: The A system light will remain illuminated for approximately five seconds after A hydraulic system is activated.
STANDBY HYDRAULIC LOW QUANTITY Light
Illuminated (amber) –
.
indicates low quantity in standby hydraulic reservoir
.
always armed.
STANDBY HYDRAULIC LOW PRESSURE Light
Illuminated (amber) –
.
indicates output pressure of standby pump is low
.
armed only when standby pump operation has been selected or automatic
standby function is activated.
ALTERNATE FLAPS Master Switch
OFF (guarded position) – normal operating position.
ARM – closes trailing edge flap bypass valve, activates standby pump, and arms ALTERNATE FLAPS position switch.
STBY RUD ON Light
Illuminated (amber) - indicates the standby hydraulic system is commanded on to pressurize the standby rudder power control unit.
Copyright . The Boeing Company. See title page for details.
13.10.6 December 5, 2003
737 Operations Manual
Hydraulics Chapter 13
System Description Section 20
Introduction
The airplane has three hydraulic systems: A, B and standby. The standby system is used if system A and/or B pressure is lost. The hydraulic systems power the
following airplane systems:
.
flight controls
.
leading edge flaps and slats
.
trailing edge flaps
.
landing gear
.
wheel brakes
.
nose wheel steering
.
thrust reversers
.
autopilots
Either A or B hydraulic system can power all flight controls with no decrease in airplane controllability.
Each hydraulic system has a fluid reservoir located in the main wheel well area. System A and B reservoirs are pressurized by bleed air. The standby system reservoir is connected to the system B reservoir for pressurization and servicing. Pressurization of all reservoirs ensures positive fluid flow to all hydraulic pumps.
Hydraulic Power Distribution Schematic
AIR PRESSURE SYSTEM
A
ALTERNATE
BRAKES
AUTOPILOT A
M M
PTU CONTROL VALVE
NUMBER 1 THRUST REVERSER
INBOARD
FLIGHT SPOILER
NOSE WHEEL STEERING
GROUND
SPOILERS
STBY
SYSTEM
RUDDER
AILERONS
ELEVATOR AND
ELEV FEEL
LANDING
GEAR
LANDING GEAR
TRANSFER UNIT
M
POWER TRANSFER UNIT
AUTO SLATS
AND
LEADING EDGE
FLAPS & SLATS
NUMBER 2 THRUST REVERSER
OUTBOARD FLIGHT SPOILER
ALTERNATE NOSE WHEEL STEERING
1
AUTOPILOT B
AIR
SYSTEM
PRESSURE
B
YAW
DAMPER
NORMAL
BRAKES
TRAILING
EDGE FLAPS
As installed
Hydraulics -System Description 737 Operations Manual
A and B Hydraulic Systems
Components powered by hydraulic systems A and B are:
System A
.
ailerons
.
rudder
.
elevator and elevator feel
.
flight spoilers (one on each wing)
.
ground spoilers
.
alternate brakes
.
No. 1 thrust reverser
.
autopilot A
.
normal nose wheel steering
.
landing gear
.
power transfer unit (PTU)
System B
.
ailerons
.
rudder
.
elevator and elevator feel
