Landing Gear and Brakes

Question 1

Are Brakes De-Pressurized during FLT

Answer 1

Yes

1. 10 seconds after Liftoff
2. Gear Handle in UP position
3. Wheel Speed is 0

Question 2

How is Alternate Landing Gear Extension Powered

Answer 2

Mechanically Powered, Gravity Actuated

Question 3

What are 4 Functions of the 2 BCM’s and 1 ABM

Answer 3

Anti-Skid
Touchdown Protection
Locked Wheel
Auto Wheel Braking

Question 4

What 4 Actions Cancel Auto-Brakes

Answer 4

1. Auto Brake Selector knob to OFF
2. Brake Pedals are Applied (Wheel Speed Above 60 kts if RTO is selected
3. Brake Control System Failure (Below 60 kts if RTO is selected)
4. Either TL applied beyond IDLE during Auto Brake application

Question 5

What are Fusible Plugs on wheels used for

Answer 5

Pins attached to the wheels, which melt relieving tire pressure in case of tire overheat

Question 6

How does Alternate Gear Extension work

Answer 6

1. Press the button on top of Alternate Gear Lever that allows it to be Actuated
2. Pull the Handle Up
3. Opens Free-Fall selector valve, Depressurizes the Landing Gear Hydraulic lines and releases all Gear Uplocks

Question 7

What Protection are provided for Braking

Answer 7

1. Touchdown (No Braking until 3 seconds or >50 kts wheel speed
2. Locked Wheel (allows up to 33% Braking for Steering purposes)
3. Anti-Skid (compares wheel speed and releases pressure)
4. Auto Wheel Braking (prevents MLG from being Retracted with wheels spinning)

Question 8

How does the Electric Override for Landing Gear work

Answer 8

1. Move SWT from Normal to Gear Down position
2. This will By-Pass Proximity Sensor Electronic Module (PSEM) and goes direct to LG selector valve to Open FWD and AFT Gear Doors and Extend the Gears

Question 9

How many WoW Sensors are there and what monitors the WoW Sensors

Answer 9

6 WoW Sensors monitored by 2 PSEM’s that send signals to EICAS Messages

Question 10

What are the Limits for Nose Wheel Steering

Answer 10

Angle varies with Ground Speed

1. Up to 40 kts - 76*
2. From 40 kts to 100 kts decreases linearly from 76* to 7*

Question 11

How are the Brakes Commanded

Answer 11

1. Brakes by Wire (Electrically commanded and Hydraulically Actuated)
2. Pedal Position Transducers send Brake requests to BCM

Question 12

What is the purpose of DN LOCK RLS Button

Answer 12

1. Mechanically releases the Landing Gear Lever Lock

2. Lock protects against inadvertent LG Retraction when WoW

Question 13

Can LG Aural Warning be Silenced by pushing the LG WRN INHIBIT Button

Answer 13

Only if both Radar Altimeters have Failed

Question 14

When will Aural Warning for LG Sound

Answer 14

If Gear is NOT Down and Locked and:

1. <700’ RA
2. Low TLA (45* for both Engines, 59* OEI)
3. Any Altitude with Flaps 5 or >

Question 15

What stops the Wheels from spinning during Retraction

Answer 15

Main Gear = BCM applies brakes after WoW

Nose Gear = Snubbers in the Nose Bay stop the Wheels from spinning