Boeing 737-800 - 20 System Description; Introduction; Pilot Controls

737 Flight Crew Operations Manual
Flight Controls Chapter 9
System Description Section 20
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D6-27370-866-EGP 9.20.1
20 System DescriptionSystem DescriptionFile Highlight
Introduction
The primary flight control system uses conventional control wheel, column and
pedals linked mechanically to hydraulic power control units which command the
primary flight control surfaces; ailerons, elevators and rudder. The flight controls
are powered by redundant hydraulic sources; system A and system B. Either
hydraulic system can operate all primary flight controls. The ailerons and
elevators may be operated manually if required. The rudder may be operated by
the standby hydraulic system if system A and system B pressure is not available.
The secondary flight controls, high lift devices consisting of Trailing Edge (TE)
flaps and Leading Edge (LE) flaps and slats (LE devices), are powered by
hydraulic system B. In the event hydraulic system B fails, the TE flaps can be
operated electrically. Under certain conditions the Power Transfer Unit (PTU)
automatically powers the LE devices. (Refer to Chapter 13, Hydraulics, Power
Transfer Unit). They can also be extended using standby hydraulic pressure.
Pilot Controls
The pilot controls consist of:
The columns and wheels are connected through transfer mechanisms which allow
the pilots to bypass a jammed control or surface.
There is a rigid connection between both pairs of rudder pedals.
The SPEED BRAKE lever allows manual or automatic symmetric actuation of the
spoilers.
• two control columns
• two control wheels
• two pairs of rudder pedals
• SPEED BRAKE lever
• FLAP lever
• STAB TRIM cutout switches
• STAB TRIM override switch
• stabilizer trim switches
• stabilizer trim wheel
• AILERON trim switches
• RUDDER trim control
• YAW DAMPER switch
• ALTERNATE FLAPS master
switch
• alternate flaps position switch
• FLT CONTROL switches
• flight SPOILER switches
September 28, 2006