Landing Gear and Brakes Flashcards
What hydraulic system powers normal extension and retraction of the landing gear?
Left hydraulic system
What system controls and monitors the position of the landing gear?
PSEU - Proximity Sensing Electronic Unit
What locks the main gear into the down position?
Internal segmented downlocking mechanism inside the actuator
What holds the gear in the up position?
Mechanical uplocks hold the gear in the up-and-locked position
How is the nose gear centered on retraction?
The steering control unit (SCU) electronically centers the nose gear
What locks the nose gear in the down position?
A spring-operated external lock mechanism on the drag brace mechanically locks the nose gear in the down position
The PSEU monitors what items on the aircraft? (4)
- Landing gear
- Aircraft doors
- Thrust levers
- Spoiler position
How many proximity sensors are on the landing and nose gear?
Dual sensors on each main gear and dual sensors on the nose landing gear
A GEAR DISAGREE caution will occur when what three things exist?
- Any gear in transit for more than 28 seconds
- Position of at least one gear does not agree with the gear
control lever except during normal transit - Landing gear handle left in up position during manual
extension
The gear and flaps display is removed from the primary page _______ seconds after the flaps are retracted and the gear is up?
30 seconds
The Aural GEAR is nonmutable if the following conditions occur … (3)
- Any gear not down and locked and
- Radio altimeter valid with a reading less than 500’ and
- Left and Right Thrust Levers less than 26 degrees thrust
lever angle or flaps greater than/equal to 27 degrees
The Aural GEAR is mutable if … (5)
- Any gear is not down and locked and
- Radio altimeter invalid and
- Left and Right Thrust Levers less than 26 degrees thrust
lever angle and - Altitude is less than 15,000’
- Various airspeed and flaps conditions exist
What is indicated if a Magenta symbol is displayed?
Data from the PSEU is not available or is invalid
How many downlock sensors of the two must agree for a downlocked safe condition to exist?
One
What must occur to get a valid gear up indication
The uplock sensor must detect gear up and both downlock sensors must detect gear not downlocked
The brake control unit commands a brake pressure of ______ for _______ seconds during retraction to ensure main wheels have stopped spinning as they enter the bay?
350 psi for 4 seconds
What is installed to slow the retraction of the nose landing gear?
A restrictor in the up hydraulic line for smoother retraction and less noise
During a manual release, what assists in the extension of the main landing gear?
Auxiliary extend actuators
What assists the nose gear in extending during a manual release?
Gravity and spring forces
During a manual extension, the manual selector valve admits pressure from __________ to both auxiliary extend actuators to assist the main landing gear into downlock?
The right hydraulic system supported by an accumulator
After a landing following an actual gear failure, what must occur?
The manual release handle should be stowed only after the gear pins have been installed
What is the maximum speed for the tires?
182 knots
What does each channel of the brake control system actually control?
One channel controls braking and antiskid operation for the inboard wheels while the second channel controls the outboard wheels
What conditions must the brake control system detect to apply hydraulic pressure on landing?
Either left or right WOW input from proximity sensors for more than 5 seconds or
Wheel spin-up greater than 50 knots
The brake control unit monitors wheel speed transducers to provide anti-skid protection down to ______ knots?
10 knots
The BCU also uses wheel speed transducers to provide outputs for __________ and __________ deployment?
- Spoiler and
- Thrust Reverser
The shutoff valves will remove hydraulic pressure to the BCU valves to disarm the BCU during flight when … ? (3)
- Weight-off-wheel on both main landing gears and
- Landing gear handle is up and
- Wheel speeds and velocity equal zero
The brake accumulator provides pressure to __________ ?
The outboard brakes
The brake accumulator receives pressure from what hydraulic system?
Right hydraulic
The emergency/parking brake meters hydraulic system pressure to what brakes?
All four main wheel brakes
The emergency/parking brake receives pressure from what hydraulic system?
Left hydraulic
Anti-skid BCU comparison is between what wheels?
The wheels on the same gear assembly and
Between each wheel on the same brake system (outboard or inboard) L inboard to R inboard and L outboard to R outboard
NWS is operable when what conditions are met (5) ?
- Left hydraulic system pressurized
- Nose gear down and locked
- Nose gear in a WOW condition
- NWS selected ON
- No faults detected by the SCU
Full authority of the NWS left and right is … ?
65 degrees
Rudder pedal command nosewheel steering up to … ?
7 degrees
With the torque link attached, the gear can only be rotated _______ in either direction?
120 degrees
With the torque links disconnected, how much chrome is necessary to be showing for towing at any angle?
3.5 inches of chrome visible
