Oral: Landing Gear & Brakes Questions

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…

a) < 700’ RA and low TLA, or
b) 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 graceperiod)

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

1) Brake by Wire
2) Electrically commanded and hydraulically actuated
3) Pedal position transducers send brake requests to the BCM (Brake Control Module)

Question 10

What hydraulic system(s) provide brake pressure?

Answer 10

1. HYD 1 Outboard brakes
2. HYD 2 Inboard brakes
3. 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.wheelspeed 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?

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

Question 15

What are the limits for the nosewheel steering?

Answer 15

Angle varies with ground speed.
•(Up to 40 kts) +76°
•(41 to 100 kts) Decreases linearly from 76° to 7°