Landing gear & Brakes Flashcards
Outboard Brakes
Outboard Brakes
Each main gear has both inboard and outboard brakes.
Hydraulic system 1 powers the outboard brakes.
Landing gear
Landing gear retraction and extension is powered by hydraulic system 2.
If EDP 2 (or engine 2) fails, the PTU assists in landing gear extension and retraction.
Onboard brakes and Nosewheel steering
Each main gear has both inboard and outboard brakes.
Hydraulic system 2 powers the inboard brakes and nosewheel steering.
Emergency/Parking Brake Accumulator
It stores hydraulic pressure from system 1 and 2 for the sole use of the Emergency/Parking Brake.
If hydraulic system 1 and 2 are depressurized, it provides enough pressure for 6 emergency/parking brake applications.
“Steer Off” displayed EICAS
STEER OFF displayed when steering is disconnected
• Hydraulic System 2 depressurized
•Steering disconnect switch is pressed (do not need to hold disconnect switch)on Yolk
•External Steering Disengage switch is set to DISENGAGE
Emergency Accumulator Pressure
The EMER ACCU PSI is shown on systems status page. If the indications are green, then there should be adequate pressure for the emer/parking brake to work
If indications are yellow (amber), the accumulator can be recharged by turning on the ACMPs in hydraulic system 1 and 2
Brake temperature Indication.
Found on systems status page. Both inboard and outboard brake temperatures must be in the green prior to takeoff
Auto Brake Selector Knob
RTO is a takeoff setting
LO/MED/HI are landing settings.
RTO (Rejected Takeoff) Setting
Automatically applies maximum braking during a rejected takeoff.
Recognizes a rejected takeoff by:
• Wheel speed above 60 kts, and
•Thrust levers in IDLE or REV (including MAX REV)
Releases the brakes when:
• Brake pedal pressure is applied (20%), or
•System faults (below 60 kts), or Thrust levers greater than IDLE
AutoBrake Lo setting
Automatically applies low braking on landing (gently applies brakes 2 seconds after weight on wheels).
Applies brakes to slows the airplane at about 2 knots per second (or 0.12 G’s).
Used for runway with adequate runway available
AutoBrake Med setting
Automatically applies medium braking on landing (applies brakes 2 seconds after weight on wheels).
Applies brakes to slows the airplane at about 4 knots per second (or 0.24 G’s)
-used on short or contaminated runways
AutoBrake Hi setting
Automatically applies high (not maximum) braking on landing (applies brakes 2 seconds after weight on wheels).
Applies brakes to slows the airplane at about 8 knots per second (or 0.41 G’s)
Rarely used do to aggressive and almost half g
When does Emergency/Parking Brake Light Illuminate?
ON is displayed when the emergency/parking brake is actuated and there is hydraulic pressure on the brake line.
DownLock release Button (Red)
The aircraft has WOW (Weight-on-wheels) sensors. When the WOW sense “on the ground”, the landing gear lever is mechanically locked in the down position.
Pressing the DN LOCK REL button overrides this protection and allows the landing gear lever to be moved regardless of the WOW sensors.
Landing Gear Lever
Commands normal extension and retraction of the landing gear (requires hydraulic pressure in system 2).
Landing Gear Warning Inhibition Button
If the gear is not down and locked when the system detects an intention to land the airplane, the aural “LANDING GEAR” is announced.
Pressing this button inhibits this warning (white bar illuminates, will not inhibit the warning if flaps are 5 or FULL).
Alternate Gear Extension Compartment
When pulled (Lever), releases hydraulic pressure in the landing gear lines and mechanically releases all landing gear uplocks. The gear extends via gravity and aerodynamic forces. If a main gear does not fully extend, it may be necessary to yaw the aircraft to add aerodynamic force to fully extend the main gear.
Electrical override switch (Landing Gear)
Electrical Override Switch( 2 Positions)
• NORMAL: Allows the Landing Gear Lever to extend and retract the landing gear.
• GEAR DOWN: Electronically bypasses the sensors and evaluation computers, and extends the landing gear.
Rudder Pedals / Braking
The rudder pedals allow for brake-by-wire and steerby wire.
Brake wear is monitored by wear pins
(4 per main gear).
Rudder Pedals The BCMs (Brake Control Modules) add protection: (4)
Antiskid protection
Automatic Wheel braking
Touchdown Protection
Locked wheel Protection
Rudder Pedals The BCMs (Brake Control Modules) add protection: Anti-skid Protection
prevents tire skidding and maximizes brake efficiency
Active at 10 kts or greater wheel speed
Rudder Pedals The BCMs (Brake Control Modules) add protection: Automatic wheel braking
Stops the main Gear during landing Gear retraction
Rudder Pedals The BCMs (Brake Control Modules) add protection: Locked wheel Protection
prevents locked wheels by comparing inboard/outboard speeds
•Active above 30 kts
Rudder Pedals The BCMs (Brake Control Modules) add protection: Touchdown Protection
Prevents the airplane from touching down with brakes applied. On landing, it only allows braking after:
• Wheel speed is above 50 knots, or
•3 seconds after touchdown.
Rudder Pedals - Nosewheel Steering
The rudder pedals can steer 7⁰ left/right.
Note: The steering must be engaged. To engage steering, hydraulic system 2 must be pressurized and the handwheel steering (tiller) must be pressed and released.
When the emergency/parking brake is set, the pilot can verify adequate pressure by looking at:
The EMERG/PRKG BRAKE light (below the AutoBrake Knob)
A pilot can verify that the steering is off by:
A “Steer Off” message on the EICAS
On the ground, the Electric Hydraulic Pump 2 will be automatically activated when the following conditions occur:
Engine 1 running and
Parking brake released
* ACMP will turn off 6 minutes after resetting parking brake
The PTU will be automatically started when all the following conditions are met:
Flaps not set to zero or Landing Gear not up and locked and,
• EDP 1 not failed and,
• Hydraulic reservoir 2 quantity above 12%.
