Landing Gear & Brakes *** Flashcards
Describe the OFF position of the landing gear.
• Landing gear hydraulic system is depressurized.
How many degrees can the nose-wheel steering system turn the nose gear with the tiller, and how many degrees with the rudder pedals?
- 70 degrees in either direction with the tiller
* 7 degrees with the rudder pedals
When does RTO apply maximum brake pressure?
- Airplane on the ground
- All 4 thrust levers are closed, and
- Above 85 knots.
What does the BRAKE SOURCE amber light indicate when illuminated?
• Active brake hydraulic sources (hydraulic systems 4, 1, and 2) have low pressure
What does a white, crosshatched, expanded gear position indication mean?
• Respective landing gear in transit
What does an amber X display on an expanded gear position mean?
• Landing gear position indicator inoperative
What does a white empty box on the Gear synoptic display indicate?
• Respective landing gear door position indicators inoperative
What sensing systems control in flight and ground operation of various airplane systems?
- Air/ground sensing system
* Nose gear extension 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
* Nose gear steering
What conditions must be satisfied in order for the landing gear lever lock to release?
- Main gear are tilted
* Body gear centered
Describe the sequence of events when the landing gear lever is moved UP.
- The landing gear doors open
- Automatic braking occurs
- Landing gear begin to retract.
- EICAS gives related indications
How are the landing gear held in position after retraction?
- Main gear are held in the up position by uplocks
* The nose gear is mechanically locked in the up position.
During landing gear extension, state what happens if any gear position disagrees with lever position after normal transit time.
• The EICAS changes to the expanded non-normal format
• Affected gear displayed as in transit, or UP if the gear never unlocked
from the up position.
How does the gear extend through the alternate gear extension system?
- By pushing the Alternate Gear Extend switches
- The gear uplocks and gear door latches are electrically released.
- The gear free-falls
- Gravity and air loads extend the gear
- Springs pull the downlocks into the locked position
When does body gear steering operate?
• When the nose wheel steering angle exceeds 20 degrees
When is body gear steering activated and when is it deactivated?
- Activated Ground speed decreasing through 15 knots
* Deactivated Ground speed increasing through 20 knots
What is the purpose of the brake accumulator?
• Provides parking brake application
Describe the difference between normal and alternate anti-skid braking systems.
• Normal brake antiskid provides each main gear wheel with individual
antiskid protection.
• Alternate brake antiskid provides antiskid protection to lateral wheel pairs
(forward and/or aft pair on each truck), rather than to individual wheels
How does the brake torque limiter function in the Alternate brake system?
- Brake torque is sensed on an individual wheel basis.
- Signal sent to alternate anti-skid valve.
- Brake pressure is released on a laterally paired wheel basis.
When do the auto brakes apply after landing?
- All thrust levers are closed
- Ground mode sensed
- The wheels have spun up
Which systems contribute to total airplane deceleration on landing and reduces autobrake pressure?
- Thrust reverse
* Spoilers
Give examples of what would disarm the autobrakes after landing.
• Pedal braking applied
• Any Thrust lever advanced after landing
• Speedbrake lever moved to DOWN detent after speedbrakes have been
deployed on the ground
• DISARM or OFF position selected on the Autobrakes selector
• Autobrake fault
• Normal antiskid system fault
• Loss of normal hydraulic pressure
What hydraulic system pressurizes the brake accumulator?
• System 4
Can the airplane be stopped with normal accumulator pressure?
• No, the accumulator is not designed to stop the aircraft.
Why is it necessary to pressurize hydraulic system 4 before pressurizing the other systems?
• Precludes the transfer of hydraulic fluid from system 1 or 2 into system
4, when the parking brake is set, and then released.
What provides automatic brake source selection?
• Pressure-operated selector valves
What value on the brake temperature monitoring system causes the BRAKE TEMP Advisory EICAS message to appear?
• 5
Is autobrake system available when alternate braking system is in use?
No, only primary.
Landing gear DOWN sequence of events?
- Doors open
- Gear are unlocked
- Gear hydraulically powered DOWN
- Door close
- Main gear trucks tilt to flight position
What EICAS landing gear position displays when alternate extension system is used?
Expanded gear position indication.
Nosewheel and body gear steering HYD SYS?
HYD SYS 1
What happens to body gear as speed increases through 20 knots?
Hydraulically centered
Do nose wheel have brakes installed?
NO
Normal braking HYD SYS?
HYD SYS 4
If HYD SYS 4 pressure is low for braking, what happens?
HYD SYS 1 supplies pressure to the alternate brake hydraulic system.
Placing AUTOBRAKES selector in DISARM does what?
- Disengages autobrake
- Releases brake pressure
Brake temp values on EICAS range from?
0 to 9
With regards to gear position indications, white crosshatch means?
In transit
AUTOBRAKES are only available when what braking system is functioning?
Primary, meaning HYD SYS 4 providing system pressure.
Is antiskid protection provided during AUTOBRAKE operation?
Yes,
AUTOBRAKE upon landing provides braking until?
Complete stop or system disarmed.
When AUTOBRAKE system is disarmed upon landing (by using pedals braking for instance), where does selector move to?
DISARM
Where does AUTOBRAKE selector move to during takeoff?
Remain in RTO, even if disarmed. Moves to OFF after takeoff.
What decides which HYD SYS controls braking application?
Pressure operated selected valves
Is the RTO function of the AUTOBRAKES system available under 85 knots?
NO
Difference between OFF and DISARM switch positions on AUTOBRAKE PANEL?
- OFF will disarm and reset system
- DISARM will disarm system and release all brake pressure to the wheels.
When do AUTOBRAKES engage after touchdown?
- Weight on wheels
- Wheels spin up
- ALL Thrust Levers CLOSED
What does it mean when the Brake Source light is illuminated on the Captain’s panel?
Active brake source (Hydraulic systems 4, 1 and 2) have low pressure
What is the difference between the normal and alternate brake systems?
Normal system operates off hydraulic system 4. Autobrakes and full anti-skid is available.
The alternate system operates off hydraulic system 1(if 4 fails) then 2 (if 1 fails). Anti-skid is reduced to pairs of wheels and autobrakes are not available.
Can I select autobrakes when hydraulic system 1 is the active brake source?
No
Above what ground speed does the RTO function become available?
85 knots
