Chapter 13: Landing Gear and Brakes

Question 1

LG WRN INHIB Pushbutton

Answer 1

Inhibits landing gear aural warning in event of radio altimeter failure
Deactivated if:
-TLA > 45 (two engines operative)
-TLA > 59 (one engine inoperative)
-Flaps 5 or FULL without gear down and locked

Question 2

PSEM and WOW Sensors

Answer 2

• Two (2) PSEMs each monitor all six (6) WOW sensors (2 per wheel)
• Inputs are logically (Boolean) combined
• If two (2) WOW fail on the same wheel, the landing gear lever will be locked in the down position

Question 3

Landing Gear Control System

Answer 3

• Commanded through landing gear lever and controlled by SPDA
• If landing gear lever failure, can be commanded through override switch
• If loss of hydraulic pressure, can be extended through alternate gear extension lever

Question 4

Landing Gear Commanded UP

Answer 4

• Hydraulic pressure released from landing gear locks
• Actuators pressurized to retract gear
• Held in place by mechanical uplocks
• PSEM detects WOW => SPDA commands gear lever locked in DOWN position
• Override switch bypasses PSEM to extend the gear

Question 5

Alternate Gear Extension

Answer 5

Pulling alternate gear extension lever…

 - Releases uplocks
 - Relieves hydraulic pressure allowing gear to freefall

Question 6

Downlock Release Button

Answer 6

Bypasses WOW protection for gear retraction

Should ONLY be used for obstacle clearance

Question 7

Landing Gear Aural Warning

Answer 7

Provides aural warning if gear is not down and locked in the following conditions:

• Flaps 5 or FULL (cannot be silenced)
• Other flap settings
  
  • RA < 700’ and
  • TLA < 45 (both engines operative)
  • TLA < 59 (one engine inoperative)

Question 8

Brake By Wire Components

Answer 8

• Two (2) Brake Control Modules (BCM)
  
  • BCM 1: DC ESS BUS 1
  • BCM 2: DC ESS BUS 2
• One (1) Auto Brake Control Module (ABM)
  
  • ABM: DC BUS 2

Question 9

Brake By Wire Protections

Answer 9

• Locked wheel protection
• Antiskid protection
• Automatic wheel braking
• Touchdown protection

Question 10

Locked Wheel Protection

Answer 10

• Active when wheel speed > 30 kt
• Senses when there is a 33% speed differential between L/R sides
• Commands zero pressure to slower wheel

Question 11

Antiskid Protection

Answer 11

• Prevents tire skidding by reducing hydraulic pressure, if necessary
• Deactivated below 10 kt
• Not available with the emergency/parking brake

Question 12

Automatic Wheel Braking

Answer 12

• Stops main wheels during retraction

- Mechanical device stops nose gear

Question 13

Touchdown Protection

Answer 13

• Prevents touchdown with brakes applies

- Deactivated three (3) seconds after WOW or wheel speed > 50 kt

Question 14

Emergency Parking Brake Accumulators

Answer 14

• Located in hydraulic systems 1 and 2

- Six (6) full brake applications

Question 15

Autobrake Arming Conditions

Answer 15

Landing Modes

- In-flight
- Wheel speed < 60 kt
- No faults
- Brakes not pressed
- Any TLA

RTO Mode

- On ground
- Wheel speed < 60 kt
- No faults
- TLA idle or rev

Question 16

Autobrake Activation Criteria

Answer 16

Landing and RTO Modes

- On Ground (must be at least two seconds for landing modes)
- Wheel speed > 60 kt
- No faults
- Brakes not pressed
- TLA idle or rev

Question 17

Autobrake Deactivation Criteria

Answer 17

Landing Modes

- Fault detected
- Brakes > 20%
- TLA above idle

RTO Mode

- In flight
- Fault detected below 60 kt
- Brakes pressed while autobrake applied
- TLA above idle while autobrakes applied

Question 18

Max Turning Radius

Answer 18

E170: 54’ 3” (horizontal stabilizer)
E175: 57’ 3” (horizontal stabilizer)
E175 EWT: 57’ 10” (wingtip)