Landing Gear and Brakes

Question 1

How is the landing gear extended and retracted?

Answer 1

Electrically commanded and hydraulically actuated

Question 2

When will the aural warning for the landing gear sound?

Answer 2

If the gear is not down and locked with flaps 5, or
B. SLAT/FLAP lever in the 0, 1, 2, 3 or 4 position
(1) Radio altitude below 700 ft AGL, and
(2) Either thrust lever is set below 45° for two operative engines, or
(3) Thrust lever is set below 59° for a one-engine inoperative condition.

Question 3

Can the landing gear aural warning be silenced by pushing the LG WRN INHIB button?

Answer 3

Only if both radio altimeters have failed

Question 4

What are three landing gear extension modes?

Answer 4

Normal: Lever down
Electric override: Bypasses PSEM to directly command selector valve
Alternate gear extension: Manual uplock release opens free-fall sequencing valve

Question 5

What is the purpose of the DN LOCKS RLS button on the landing gear lever?

Answer 5

Mechanically releases the landing gear lever lock

Lock protects against inadvertent landing gear retraction when weight-on-wheels

Question 6

What keeps the gear locked in position?

Answer 6

Extended: Downlock springs
Retracted: Uplock hooks

Question 7

Describe the landing gear indications

Answer 7

Green: Down and locked
White: Up and locked
Amber: In transit
Red: Gear position and lever disagreement

Question 8

How do the landing gear doors actuate?

Answer 8

Mechanically, during landing gear extension or retraction

Question 9

How are the brakes commanded?

Answer 9

Brake by wire
Electrically commanded and hydraulically actuated
Pedal position transducers send brake request to BCM

Question 10

What hydraulic systems provide brake pressure?

Answer 10

HYD 1: Inboard
HYD 2: Outboard
HYD 1 & 2: Parking/emergency brake

Question 11

What protections are provided for braking?

Answer 11

Touchdown:No braking until 3 seconds or > 50kts wheel speed

Anti-skid: Compares wheel speeds and releases pressure (inop

Question 12

How many applications will the parking/emergency brake provide?

Answer 12

6

Question 13

What stops the wheels from spinning during retraction?

Answer 13

Main gear: BCM applies brakes after weight off wheels

Nose gear: Snubbers in the nose bay

Question 14

Which hydraulic system controls the nosewheel steering?

Answer 14

HYD 2

Question 15

What are the limits for the nosewheel steering?

Answer 15

Angle varies with groundspeed
Up to 40kts: 76 deg
41 to 100 kts: Decreases linearly from 76 to 7