Landing Gear Flashcards
Describe the OFF position of the landing gear?
Hydraulic pressure relieved
Gear held mechanically
How many degrees can the nose wheel steering system turn the nose and body?
Nose
- Tiller: 70deg
- rudder pedals: 7deg
(Tiller overrides rudder pedals)
Body
- follows nose after nose exceeds 20deg
When does RTO apply maximum brake pressure?
On the ground
- with the RTO armed
- grnd speed above 85kts
- all thrust levers to closed
What does the BRAKE SOURCE amber light indicate when illuminated?
Loss of Hydraulic systems 4,1 and 2
- down to accumulator pressure
What does a white cross hatched expanded gear position indication mean?
Respective landing gear in transit
What does an amber X display on an expanded gear position mean?
Landing gear indicator INOP
What does an empty box on the Gear Synoptic display indicate?
Respective landing gear door position indicator INOP
What sensing system control in flight and ground operations of various airplane systems
Air/Ground sensing system and nose gear sensing system
How does the airplane distinguish between air mode and ground mode
A combination of main gear tilt sensors
Nose gear extension sensing provides a signal to relays controlling functions in which systems
Stall warning and nose gear steering
What conditions must be satisfied in order for the landing gear lever lock to release
Main gear tilted
Body gear centered
Describe the sequence of events when the landing gear lever is moved to UP
- EICAS gear position indication changes from DOWN (green) to (white) crosshatched transit indication
- As gear retract automatic wheel braking is applied
- During retraction main gear tilt to retracted position
- After retraction (and release to off) main gear held by up-locks
- EICAS changes to UP (white) for 10 sec and then blanks
How are the landing gear held in UP position after retraction
Mechanical locks. Lever to off depressurizes hydraulics
During landing gear extension or retraction what happens if any gear position disagrees with the lever position after normal transit time
EICAS message GEAR DISAGREE appears and a beeper activates. The gear position indication changes to the expanded non-normal format
How does the gear extend through alternator gear extension system?
- The gear of the associated hydraulic system (hyd 1 for nose and body and hyd 4 for wing) will freefall when associated switch is pushed
- pressing an alternator Gear Extend switch releases the associated gear up-locks and gear doors allowing free fall gravity and air loads extend the gear and prints pull the down locks into position
- EICAS displays expanded gear position indication display
- all hydraulic operated gear doors remain open
- may be directed to push one or both switches
- nose/body switch will also reactive steering for Hyd sys 1, stop straight ahead, have gear pinned and get towed
When does body gear steering operate?
When nose gear steering angle exceeds 20deg
- no direct control follows nose 20-70
- activates below 15deg
- deactivates above 20kts
- reactivates below 15deg
When is body gear steering deactivated
Above 20kts
What is the purpose of the brake accumulator?
Provides parking brake application
Describe the difference between normal and alternate anti skid braking
Normal: each main gear individual anti skid protection
Alt: anti-skid protection provided to laterally paired wheels
How does breaker torque limiter function in the alternate brake system
Senses excessive braking
- norm brakes: signals anti skid valve to release brake pressure on specific wheel
- alternate brakes: release brake pressure on alternately pared wheels
When do the auto brakes apply after landing
- Aircraft on the ground
- wheel spin up detected
- all thrust levers closed
Which systems contribute to total airplane deceleration on landing?
- Spoilers
- Thrust reversers
- Brakes
Give examples of what would disarm the auto brakes after landing?
Crew Actions:
- brake pedal being applied
- any thrust lever advanced after landing
- speed brake lever DOWN
- DISARM or OFF selected
SYS Faults
- Autobrake Fault
- Normal Anti-skid System Fault
- Loss of normal brake hydraulic pressure
What hydraulic system pressurizes the brake accumulator
Hydraulic system 4
(Used to set parking brake - not set aircraft)
Can the airplane be stopped with normal accumulator pressure?
No.
Why is it necessary to pressurize hydraulic system 4 before pressurizing the other systems?
To prevent fluid transfer from hydraulic system 1 or 2 into system 4 when the parking brake is set and then released
Note: brake hydraulic return lines dump into Hydraulic System 4
What provides automatic brake source selection?
Pressure-operated selector valves.
What value on the brake temperature monitoring system causes BRAKE TEMP advisory EICAS message to appear
- Brake temp equal pro greater than 5 units
Note: range 0-9 - Normal range: 0-4 (white)
- Highg range: 5-9 (amber)
