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737ng机型熟悉讲义
附件包括：
B737NG系统学习第01部（外部检查）.pdf
B737NG系统学习第02部（警告系统）.pdf
B737NG系统学习第03部（气源系统）.pdf
B737NG系统学习第04部（防冰防雨）.pdf
B737NG系统学习第05部（APU系统）.pdf
B737NG系统学习第06部（电源系统）.pdf
B737NG系统学习第07部（发动机）.pdf
B737NG系统学习第08部（火警系统）.pdf
B737NG系统学习第09部（飞行控制）.pdf
B737NG系统学习第10部（燃油系统）.pdf
B737NG系统学习第11部（液压系统）.pdf
B737NG系统学习第12部（起落架）.pdf
Landing Gear
Introduction
The airplane has two main landing gear and a single nose gear. Each main gear is
a conventional two–wheel landing gear unit. The nose gear is a conventional
steerable two–wheel unit.
Hydraulic power for retraction, extension, and nose wheel steering is normally
supplied by hydraulic system A. A manual landing gear extension system and an
alternate source of hydraulic power for nose wheel steering are also provided.
The normal brake system is powered by hydraulic system B. The alternate brake
system is powered by hydraulic system A. Antiskid protection is provided on both
brake systems, but the autobrake system is available only with the normal brake
system.
[Aircraft Option]
A brake temperature monitoring system displays each main landing gear brake
temperature on the lower DU.
Landing Gear Operation
The landing gear are normally controlled by the LANDING GEAR lever. On the
ground, a landing gear lever lock, prevents the LANDING GEAR lever from
moving to the up position. An override trigger in the lever may be used to bypass
the landing gear lever lock. In flight, the air/ground system energizes a solenoid
which opens the lever lock.
Landing Gear Retraction
When the LANDING GEAR lever is moved to UP, the landing gear begins to
retract. During retraction, the brakes automatically stop rotation of the main gear
wheels. After retraction, the main gear are held in place by mechanical uplocks.
Rubber seals and oversized hubcaps complete the fairing of the outboard wheels.
The nose wheels retract forward into the wheel well and nose wheel rotation is
stopped by snubbers. The nose gear is held in place by an overcenter lock and
enclosed by doors which are mechanically linked to the gear.
Page 1
Hydraulic pressure is removed from the landing gear system with the LANDING
GEAR lever in the OFF position.
If a main landing gear tire is damaged during takeoff, it is possible that braking of
the main gear wheels during retraction may be affected. A spinning tire with a
loose tread must be stopped prior to entering the wheel well or it can cause damage
to wheel well components. When a spinning tire with loose tread impacts a fitting
in the wheel well ring opening, that gear stops retracting and free falls back to the
down position. The affected gear cannot be retracted until the fitting is replaced.
Landing Gear Transfer Unit
Hydraulic system B pressure is available for raising the landing gear through the
landing gear transfer unit. Hydraulic system B supplies the volume of hydraulic
fluid required to raise the landing gear at the normal rate when all of the following
conditions exist:
• airborne
• No. 1 engine RPM drops below a limit value
• LANDING GEAR lever is positioned UP
• either main landing gear is not up and locked.
Landing Gear Extension
When the LANDING GEAR lever is moved to DN, hydraulic system A pressure
is used to release the uplocks. The landing gear extends by hydraulic pressure,
gravity and air loads. Overcenter mechanical and hydraulic locks hold the gear at
full extension. The nose wheel doors remain open when the gear is down.
Landing Gear Manual Extension
If hydraulic system A pressure is lost, the manual extension system provides
another means of landing gear extension. Manual gear releases on the flight deck
are used to release uplocks that allow the gear to free–fall to the down and locked
position. The forces that pull the gear down are gravity and air loads.
With the manual extension access door open:
• manual landing gear extension is possible with the LANDING GEAR
lever in any position
• normal landing gear extension is possible if hydraulic system A pressure
is available
• landing gear retraction is disabled.
Following a manual extension, the landing gear may be retracted normally by
accomplishing the following steps:
• close the manual extension access door
• move the LANDING GEAR lever to DOWN with hydraulic system A
pressure available, and then
• position the LANDING GEAR lever to UP.
Page 2
Nose Wheel Steering
The airplane is equipped with nose wheel steering which is powered by hydraulic
system A when the NOSE WHEEL STEERING switch is in the NORM position.
Nose wheel steering is powered by hydraulic system B when the NOSE WHEEL
STEERING switch is placed to ALT. Nose wheel steering is powered only when
the airplane is on the ground. In the event of a hydraulic leak downstream of the
Landing Gear Transfer Unit, resulting in a loss of hydraulic system B fluid in the
reservoir, a sensor closes the Landing Gear Transfer Valve and alternate steering
will be lost.
Primary steering is controlled through the nose wheel steering wheel. Limited
steering control is available through the rudder pedals. A pointer on the nose
steering wheel assembly shows nose wheel steering position relative to the neutral
setting. Rudder pedal steering is deactivated as the nose gear strut extends.
A lockout pin may be installed in the towing lever to depressurize nose wheel
steering. This allows airplane pushback or towing without depressurizing the
hydraulic systems.
Brake System
Each main gear wheel has a multi–disc hydraulic powered brake. The brake pedals
provide independent control of the left and right brakes. The nose wheels have no
brakes. The brake system includes:
Normal Brake System
The normal brake system is powered by hydraulic system B.
Alternate Brake System
The alternate brake system is powered by hydraulic system A. If hydraulic system
B is low or fails, hydraulic system A automatically supplies pressure to the
alternate brake system.
Brake Accumulator
The brake accumulator is pressurized by hydraulic system B. If both normal and
alternate brake system pressure is lost, trapped hydraulic pressure in the brake
accumulator can still provide several braking applications or parking brake
application.
• normal brake system
• alternate brake system
• brake accumulator
• antiskid protection
• autobrake system
• parking brake
[Aircraft Option]
• brake temperature indication
Page 3
Antiskid Protection
Antiskid protection is provided in the normal and alternate brake systems.
The normal brake hydraulic system provides each main gear wheel with
individual antiskid protection. When the system detects a skid, the associated
antiskid valve reduces brake pressure until skidding stops. The alternate brake
hydraulic system works similar to the normal system however antiskid protection
is applied to main gear wheel pairs instead of individual wheels.
Both normal and alternate brake systems provide skid, locked wheel, touchdown
and hydroplane protection.
Antiskid protection is available even with loss of both hydraulic systems.
Autobrake System
The autobrake system uses hydraulic system B pressure to provide maximum
deceleration for rejected takeoff and automatic braking at preselected deceleration
rates immediately after touchdown. The system operates only when the normal
brake system is functioning. Antiskid system protection is provided during
autobrake operation.
Rejected Takeoff (RTO)
The RTO mode can be selected only when on the ground. Upon selection, the
AUTO BRAKE DISARM light illuminates for one to two seconds and then
extinguishes, indicating that an automatic self–test has been successfully
accomplished.
To arm the RTO mode prior to takeoff the following conditions must exist:
• airplane on the ground
• antiskid and autobrake systems operational
• AUTO BRAKE select switch positioned to RTO
• wheel speed less than 60 knots
• forward thrust levers positioned to IDLE.
With RTO selected, if the takeoff is rejected prior to wheel speed reaching 90
knots autobraking is not initiated, the AUTO BRAKE DISARM light does not
illuminate and the RTO autobrake function remains armed. If the takeoff is
rejected after reaching a wheel speed of 90 knots, maximum braking is applied
automatically when the forward thrust levers are retarded to IDLE.
Page 4
The RTO mode is automatically disarmed when both air/ground systems indicate
the air mode. The AUTO BRAKE DISARM light does not illuminate and the
AUTO BRAKE select switch remains in the RTO position. To reset or manually
disarm the autobrake system, position the selector to OFF. If a landing is made
with RTO selected (AUTO BRAKE select switch not cycled through OFF), no
automatic braking action occurs and the AUTO BRAKE DISARM light
illuminates two seconds after touchdown.
Landing
When a landing autobrake selection is made, the system performs a turn–on–
self–test. If the turn–on–self–test is not successful, the AUTO BRAKE DISARM
light illuminates and the autobrake system does not arm.
Four levels of deceleration can be selected for landing. However, on dry runways,
the maximum autobrake deceleration rate in the landing mode is less than that
produced by full pedal braking.
After landing, autobrake application begins when:
• both forward thrust levers are retarded to IDLE
• the main wheels spin–up.
Note: Landing autobrake settings may be selected after touchdown prior to
decelerating through 60 kts of ground speed. Braking initiates immediately
if the above conditions are met.
To maintain the selected landing deceleration rate, autobrake pressure is reduced
as other controls, such as thrust reversers and spoilers, contribute to total
deceleration. The deceleration level can be changed (without disarming the
system) by rotating the selector. The autobrake system brings the airplane to a
complete stop unless the braking is terminated by the pilot.
Autobrake – Disarm
The pilots may disarm the autobrake system by moving the selector switch to the
OFF position. This action does not cause the AUTO BRAKE DISARM light to
illuminate. After braking has started, any of the following pilot actions disarm the
system immediately and illuminate the AUTO BRAKE DISARM light:
• moving the SPEED BRAKE lever to the down detent
• advancing the forward thrust lever(s), except during the first 3 seconds
after touchdown for landing
• applying manual brakes.
Page 5
Parking Brake
The parking brake can be set with either A or B hydraulic systems pressurized. If
A and B hydraulic systems are not pressurized, parking brake pressure is
maintained by the brake accumulator. Accumulator pressure is shown on the HYD
BRAKE PRESS indicator.
The parking brake is set by depressing both brake pedals fully, while
simultaneously pulling the PARKING BRAKE lever up. This mechanically
latches the pedals in the depressed position and commands the parking brake valve
to close.
The parking brake is released by depressing the pedals until the PARKING
BRAKE lever releases. A fault in the parking brake system may cause the
ANTISKID INOP light to illuminate.
The TAKEOFF CONFIG lights illuminate and the takeoff configuration warning
horn sounds if either forward thrust lever is advanced for takeoff with the parking
brake set.
Air/Ground System
In flight and ground operation of various airplane systems are controlled by the
air/ground system.
The system receives air/ground logic signals from six sensors, two on each
landing gear. These signals are used to configure the airplane systems to the
appropriate air or ground status.
Air/Ground System Logic Table |
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