Landing Gear & 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, and
▪< 700’ RA and low TLA, or
▪ Any altitude with flaps set > 5

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 - LG 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 LOCK 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 & locked
White Up & locked
Amber In transit
Red Gear position & lever disagreement (20 sec grace period)

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 requests to the BCM (Brake Control Module)

Question 10

What hydraulic system(s) provide brake pressure?

Answer 10

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

Question 11

What protections are provided for braking?

Answer 11

Touchdown No braking until 3 seconds or > 50 kts. wheel speed after touchdown
Anti-skid Compares wheel speeds and releases pressure (inop <10 kts)
Locked-wheel Allows up to 33% differential braking for steering purposes (inop <30 kts)

Question 12

How many applications will the parking/emergency brake provide in a HYD 1 and 2 failure?

Answer 12

6 applications

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 stop the wheels

Question 14

Which hydraulic system controls the nosewheel steering?

Answer 14

HYD 2