Boeing 767 300 Landing Gear

B767

Landing Gear DO NOT USE FOR FLIGHT

Boeing B767 - Systems Summary [Landing Gear]

Introduction The airplane has two main landing gear and a single nose gear. The nose gear is a conventional steerable two–wheel unit. Each main gear has four wheels in tandem pairs. Hydraulic power for retraction, extension, and steering is supplied by the center hydraulic system. An alternate extension system is also provided. The normal brake hydraulic system is powered by the right hydraulic system. The alternate brake hydraulic system is powered by the center hydraulic system. Antiskid protection is provided with both systems, but the autobrake system is available only through the normal system. A brake temperature monitor system displays each brake temperature on the EICAS status display.

Air/Ground Sensing System In–flight and ground operation of various airplane systems are controlled by the air/ground sensing system and the nose air/ground sensing system. The air/ground sensing system receives air/ground logic signals from tilt sensors located on each main landing gear. These signals are used to configure the airplane systems to the appropriate air or ground status. A nose air/ground sensing system receives air/ground logic signals from nose gear strut compression sensors. These signals are for controlling stall warning and portions of the caution and warning system. An EICAS advisory message AIR/GND SYS or NOSE A/G SYS indicates that some portion of the sensing system failed. Affected equipment and systems will not operate normally and therefore takeoff is not allowed.

Landing Gear Operation The landing gear are normally controlled by the landing gear lever. On the ground, the lever is held in the DN position by an automatic lever lock controlled by the main gear tilt sensor. The lever lock can be manually overridden by pushing and holding the landing gear lever LOCK OVRD switch. In flight, the lever lock is automatically released through air/ground sensing of main gear tilt sensor.

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Landing Gear Retraction When the landing gear lever is positioned to UP, the tilted landing gear begins to retract. The landing gear doors open and the gear retracts to up position. Automatic wheel braking occurs during gear retraction. The GEAR and DOORS lights illuminate as the landing gear retracts into the wheel wells. After retraction, the nose gear is held up by uplocks and the main gear is held up by the door structure. The GEAR and DOORS lights extinguish. The landing gear lever is placed in the OFF position to depressurize the landing gear system. The GEAR light remains illuminated and the EICAS caution message GEAR DISAGREE displays if any gear is not up and locked up after the normal transit time. The affected gear’s, gear down light, remains illuminated if the gear never unlocked from the down position. The DOORS light remains illuminated and the EICAS advisory message GEAR DOORS displays if any hydraulically actuated main gear door is not closed after normal transit time.

Landing Gear Extension When the landing gear lever is moved to DN, the landing gear doors open, the gear are unlocked, and the GEAR and DOORS lights illuminate. The gear are hydraulically powered to the down and locked position. The downlocks are powered to the locked position, all hydraulically actuated gear doors close, and the main gear trucks hydraulically tilt to the flight position. When all gear are down and locked, the gear down lights illuminate and the GEAR and DOORS lights extinguish. The amber GEAR light remains illuminated and the EICAS caution messages GEAR DISAGREE, L or R SIDE BRACE, L or R DRAG BRACE displays if any gear is not locked down after the normal transit time. The extinguished green gear down light indicates the affected gear. The DOORS light remains illuminated and the EICAS advisory message GEAR DOORS displays if any hydraulically actuated door is not closed after the normal transit time.

Landing Gear Alternate Extension The alternate landing gear extension system uses an electric motor to trip the locking mechanism for each gear. Selecting DN on the ALTN GEAR EXTEND switch releases all door and gear uplocks. The landing gear free–fall to the down and locked position. When all gear are down and locked, the gear down lights illuminate and the GEAR light extinguishes. During alternate extension, the DOORS light remains illuminated and the EICAS advisory message GEAR DOORS displays because all the hydraulically powered gear doors remain open.

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Nose Wheel Steering Nose wheel steering is powered by the center hydraulic system. In the event of a center hydraulic system leak, a reserve brakes and steering system can power the nose wheel steering. Primary steering control is provided by the nose wheel steering tiller.Limited steering control is available through the rudder pedals. The tiller can turn the nose wheel up to 65 degrees in either direction. A pointer on the tiller assembly shows tiller position relative to the neutral setting. The rudder pedals can be used to turn the nose wheels up to seven degrees in either direction. Tiller inputs override rudder pedal inputs.

Brake System Each main gear wheel has a multiple disc brake. The nose wheels have no brakes. The brake system includes: • normal brake hydraulic system • alternate brake hydraulic system • brake accumulator • antiskid protection • autobrake system • parking brake

Normal Brake Hydraulic System The normal brake hydraulic system is powered by the right hydraulic system. The brake pedals provide independent control of the left and right brakes.

Alternate Brake Hydraulic System Alternate brake hydraulic system selection is automatic. If the right hydraulic system pressure is low, the center hydraulic system automatically supplies pressure to the alternate brake system. Pushing a brake pedal then sends hydraulic pressure through the alternate antiskid valves to the brakes. The BRAKE SOURCE light illuminates and the EICAS advisory message BRAKE SOURCE displays if both normal and alternate brake system pressures are low.

Reserve Brakes and Steering Pressing the RESERVE BKS & STRG switch provides hydraulic fluid to the center number one electric primary hydraulic pump. Pump pressure is then supplied exclusively to the alternate brake system and nose wheel steering system. The BRAKE SOURCE light and EICAS message extinguish when pressure is available. Page 3


The VALVE light illuminates and the EICAS advisory message RSV BRAKE VAL displays if a reserve brake valve disagrees with the commanded position.

Brake Accumulator If normal and alternate brake hydraulic power is lost, the brake accumulator can provide several braking applications or parking brake application.

Antiskid Protection Antiskid protection is provided in the normal and alternate brake hydraulic systems. The normal brake hydraulic system provides each main gear wheel with individual antiskid protection. When a wheel speed sensor detects a skid, the associated antiskid valve reduces brake pressure until skidding stops. The alternate brake hydraulic system provides antiskid protection to laterally paired wheels. Touchdown, hydroplaning, and locked wheel protection are provided. The ANTISKID light illuminates and the EICAS advisory message ANTISKID displays to indicate a fault is detected in the antiskid system. The ANTISKID light illuminates and the EICAS advisory message ANTISKID OFF displays to indicate the antiskid system is inoperative.

Autobrake System The autobrake system provides automatic braking at pre–selected deceleration rates for landing. The system operates only when the normal brake system is functioning. Antiskid system protection is provided during autobrake operation. The AUTO BRAKES light illuminates and the EICAS advisory message AUTOBRAKES displays if the autobrake system is disarmed or inoperative. Rejected Takeoff Selecting RTO prior to takeoff arms the autobrake system. The RTO mode can be selected only on the ground. The RTO autobrake setting commands maximum braking pressure if: • the airplane is on the ground • groundspeed is above 85 knots, and • both thrust levers are retarded to idle Maximum braking is obtained in this mode. If an RTO is initiated below 85 knots, the RTO autobrake function does not operate. Page 4


Landing Five 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 thrust levers are retarded to idle, and • the wheels have spun up Autobrake application occurs slightly after main gear touchdown. Deceleration is limited until main landing gear truck untilt occurs, then deceleration increases to the selected level. The deceleration level can be changed (without disarming the system) by rotating the selector. To maintain the selected airplane deceleration rate, autobrake pressure is reduced as other controls, such as thrust reversers and spoilers, contribute to total deceleration. The system provides braking to a complete stop or until it is disarmed. Autobrake – Disarm The system disarms immediately, the AUTO BRAKES light illuminates, and the EICAS advisory message AUTOBRAKES displays if any of the following occur: • pedal braking applied • either thrust lever advanced after landing • speedbrake lever is moved from the full up position after the speedbrakes have deployed on the ground • DISARM or OFF position selected on the autobrakes selector • autobrake fault • normal antiskid system fault When the autobrakes system disarms after landing: • the autobrakes selector automatically moves to the DISARM position • power is removed from the autobrake system • the AUTO BRAKES light illuminates When the autobrake system disarms during takeoff, the autobrakes selector remains in the RTO position. After takeoff, the autobrakes selector automatically moves to OFF.

Parking Brake The parking brake can be set with the normal or alternate brake hydraulic system pressurized. If the normal and alternate brake systems are not pressurized, parking brake pressure is maintained by the brake accumulator. The brake accumulator is pressurized by the right hydraulic system. Accumulator pressure is shown on the BRAKE PRESS indicator. Page 5


The parking brake is set by fully depressing both brake pedals, pulling the parking brake handle up, then releasing the pedals. 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 handle releases. The PARK BRAKE light illuminates and the EICAS advisory message PARKING BRAKE displays when the parking brake is set.

Brake Temperature Indication Wheel brake temperatures are displayed on the EICAS status page. Numerical values related to wheel brake temperature are displayed for each main gear brake. Brake temperature values range from 0 to 9. Temperature values are not instantaneous and tend to build for 10 to 15 minutes after the brakes are applied. Initial range values of 0 to 2 are cyan numbers in a cyan box. For normal range values of 3 and 4, the number is cyan and the box is white for the first brake per truck that exceeds a value of 2. Values in the high range of 5 to 9 have a white number and box. The BRAKE TEMP light illuminates for values of 5 and above.

Tailskid The airplane is equipped with a tailskid system. The tailskid extends for takeoff and landing and retracts during flight. It helps to protect the pressurized part of the airplane from contact with the runway. The tailskid uses the main landing gear actuation system. The TAILSKID light illuminates and the EICAS advisory message TAILSKID is displayed when the tailskid position disagrees with the landing gear lever position.

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Landing Gear EICAS Messages The following EICAS messages can be displayed. Note: Refer to Chapter 15, Warning Systems, for configuration warning messages.

Brakes Message

Level

Light

Aural

Condition

ANTISKID

Advisory

ANTISKID

A fault is detected in the antiskid system.

ANTISKID OFF

Advisory

ANTISKID

Antiskid system is inoperative.

AUTOBRAKES

Advisory

AUTO BRAKES

Auto brakes are disarmed or inoperative.

BRAKE SOURCE

Advisory

BRAKE SOURCE

Normal and alternate brake system pressures are low.

PARKING BRAKE

Advisory

PARK BRAKE

The parking brake is set.

RSV BRAKE VAL

Advisory

VALVE

Valve(s) position disagrees with the commanded position.

Landing Gear Message AIR/GND SYS

Level

Light

Aural

Advisory

Condition Air/ground sensing system failed.

GEAR DISAGREE Caution

GEAR

GEAR DOORS

Advisory

DOORS

L DRAG BRACE R DRAG BRACE

Caution

GEAR

Beeper

The main gear drag brace is not locked down.

L SIDE BRACE R SIDE BRACE

Caution

GEAR

Beeper

The main gear side brace is not locked down.

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Beeper

Gear position disagrees with landing gear lever position. One or more gear doors are not closed.


Message NOSE A/G SYS

Level

Light

Aural

Advisory

Condition Nose air/ground sensing system failed.

Tailskid Message TAILSKID

Level

Light

Aural

Advisory

TAILSKID

Condition Tailskid position disagrees with landing gear lever position.

Landing Gear Panel [Option-Brake Temp light installed] 4 BRAKE TEMP

1 2

D O O R S

3

TAILSKID NOSE LEFT

G E A R

5

RIGHT

CENTER FORWARD PANEL 1

Brake Temperature (BRAKE TEMP) Light

Illuminated (white) – a wheel brake temperature is in high range (a value of 5 or above on the status page). 2

DOORS Light

Illuminated (amber) – a door is not closed. 3

Landing Gear Down Lights (NOSE, LEFT, and RIGHT)

Illuminated (green) – the associated landing gear is down and locked. 4

TAILSKID Light

Illuminated (amber) – the tailskid position disagrees with the landing gear lever position. 5

Landing GEAR Disagree Light

Illuminated (amber) –the gear position disagrees with the lever position.

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Option-Brake Temp light not installed] 3 D O O R S

1 2

TAILSKID NOSE LEFT

G E A R

4

RIGHT


DOORS Light

Illuminated (amber) – a door is not closed. 2

Landing Gear Down Lights (NOSE, LEFT, and RIGHT)

Illuminated (green) – the associated landing gear is down and locked. 3

TAILSKID Light

Illuminated (amber) – the tailskid position disagrees with the landing gear lever position. 4

Landing GEAR Disagree Light

Illuminated (amber) –the gear position disagrees with the lever position.

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Gear Extension/Retraction

UP

RETRACT 270K

1 OFF

EXTEND OR EXTENDED 270K-.82M DN

LOCK OVRD

3 ALTN GEAR EXTEND 250K-.75M OFF

2 DN


Landing Gear Lever

UP – the landing gear retracts. OFF – hydraulic pressure is removed from landing gear system. DN – the landing gear extends. 2

Alternate Gear Extend (ALTN GEAR EXTEND) Switch

OFF – the landing gear lever operates normally. DN (down) – the landing gear extends by the alternate extension system. 3

Landing Gear Lever Lock Override (LOCK OVRD) Switch

Push – releases the landing gear lever lock.

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Nose Wheel Steering Tiller A nose wheel steering tiller is installed on the left sidewall.

1 2

SIDEWALL 1

Nose Wheel Steering Tiller

Rotate – • turns the nose wheels up to 65 degrees in either direction • overrides rudder pedal steering 2

Tiller Position Indicator

Shows tiller displacement from the straight–ahead, neutral position.

Brake System Rudder/Brake Pedals 1

2

1

Rudder Pedal Adjust Crank

Pull and Rotate – adjusts the rudder pedals forward or aft. 2

Rudder/Brake Pedals

Push the full pedal –turns the nose wheel up to seven degrees in either direction. Page 11


Push the top of the pedals – actuates the wheel brakes. Refer to Chapter 9, Flight Controls for the description of rudder operation.

Auto Brakes Selector AUTO BRAKES

1

AUTO BRAKES 2

1

3

DISARM

2

4

OFF

MAX AUTO

RTO


AUTO BRAKES Light

Illuminated (amber) – the auto brakes are disarmed or inoperative. 2

AUTO BRAKES Selector

OFF – deactivates the autobrake system. DISARM – • disengages the auto brake system • releases brake pressure 1,2,3,4, MAX AUTO – selects the desired deceleration rate. RTO – automatically applies maximum brake pressure when the thrust levers are retarded to idle above 85 knots.

Parking Brake Handle 1

2

PARK BRAKE P A R K B R A K E

CONTROL STAND 1

Parking Brake (PARK BRAKE) Light

Illuminated (amber) – the parking brake is set.

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2

Parking Brake (PARK BRAKE) Handle

Pull – sets the parking brake when both brake pedals are simultaneously depressed. Release – simultaneously depress both brake pedals.

Brake Accumulator Pressure Indicator BRAKE 4 PRESS

1

PSIX1000

3

0

1

2


Brake Accumulator Pressure (BRAKE PRESS) Indicator

Indicates brake accumulator pressure (psi x1000).

Brake Source Light BRAKE SOURCE

1


BRAKE SOURCE Light

Illuminated (amber) – both normal and alternate brake system pressures are low.

Reserve Brakes and Steering Switch RESERVE BKS & STRG

1

ON

2

VALVE

CENTER FORWARD PANEL

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Boeing B767 - Systems Summary [Landing Gear] 1

RESERVE Brakes and Steering (BKS & STRG) Switch

ON – provides pressure to alternate brake system and nose wheel steering system. Off – (ON not visible) – the reserve brakes and steering system is commanded off. 2

Reserve Brakes and Steering VALVE Light

Illuminated (amber) – • switch OFF – valve(s) disagree with commanded position from automatic isolation feature • switch ON – valve(s) disagree with manually selected switch position

Antiskid Light 1

ANTISKID

OVERHEAD PANEL 1

ANTISKID Light

Illuminated (amber) – a fault is detected in the antiskid system.

Brake Temperature [Option-EICAS Status Display Brake Temp]

2 2

1 2

2 1

2 1

1

BRAKE TEMP

EICAS STATUS DISPLAY 1

Brake Temperature (BRAKE TEMP)

Indicates a relative value of wheel brake temperature. • values range from 0 to 9 • 0 to 2 – initial range, box and number are cyan • 3 to 4 – normal range, box is white for the first brake per truck that exceeds a value of 2 and number is cyan • 5 to 9 – high range, box and number are white for each brake with a value of 5 or above Page 14

Boeing 767 300 Landing Gear

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