Landing Gear

Question 1

Explain the operation of the landing gear

Answer 1

• flight crew normally operate landing gear via lever
• LGCIUs (1 or 2) control the sequencing of gear and doors electrically
• LGCIUs switch at the completion of each retraction cycle or failure
• green hydraulic system actuates all gears and doors
• LGCIUs electronically monitor 16 proximity switches to determine sequence of landing gear and doors.

Question 2

Does the landing gear have any protections?

Answer 2

• If aircraft is flying faster than 260 kt, a safety valve automatically cuts off hydraulic supply to the landing gear system
• interlock mechanism prevents anyone from accidentally retracting the gear while the aircraft is on the ground

Question 3

What happens when you turn the landing gear hand crank?

Answer 3

‐ Isolates the landing gear hydraulics from the green hydraulic system
‐ Unlocks the landing gear doors and the main and nose main gear
‐ Allows gravity to drop the gear into the extended position

Question 4

What information do the LGCIUs receive from the proximity detectors?

Answer 4

‐ The landing gears are locked down or up
‐ The shock absorbers are compressed or extended
‐ The landing gear doors are open, or closed
‐ The bogie are aligned or not

Question 5

Which LGCIU is connected to the Landing Gear Indicator Panel?

Answer 5

LGCIU 1

Question 6

How many turns of the crank to manually extend the landing gear?

Answer 6

3 turns

Question 7

On WHEEL SD page how to confirm if the gear is down and locked?

Answer 7

• 2 triangles for each gear

- Only one green triangle on each landing gear strut is sufficient to confirm that the landing gear is downlocked

Question 8

Which hydraulic system operates nose wheel steering?

Answer 8

Yellow hydraulic system

Question 9

What is required for the steering system to receive hydraulic pressure?

Answer 9

‐ A/SKID & N/W STRG switch is ON
‐ Towing control lever is in normal position
‐ At least one engine is running
‐ Aircraft is on ground

Question 10

Steering angle limits

Answer 10

+/- 6 degrees via rudder
+/- 75 degrees via steering hand wheel
+/- 95 degrees with steering system off for towing

Question 11

How many braking systems?

Answer 11

• normal system via green hydraulic pressure
• alternate system via the yellow hydraulic system
• anti-skid and autobrake system

Question 12

When does anti skid deactivate?

Answer 12

20 knts

Question 13

How is wheel reference speed determined?

Answer 13

• reference speed is determined by the Brake Steering Control Unit (BSCU) from the horizontal acceleration of ADIRU 1, or ADIRU 2, or ADIRU 3
• in case of all ADIRU failure reference speed equals maximum of either main landing gear wheel speeds

Question 14

Auto break arming conditions

Answer 14

‐ Green pressure available
‐ Anti-skid electrically powered
‐ No failure in the braking system
‐ At least one ADIRU is available

• MAX cannot be armed in flight

Question 15

Conditions to activate Autobrake

Answer 15

In LO or MED: ground spoilers extension
In MAX: ground spoilers extension and above 40knts
ground spoiler extend above 72knt wheel speed
- 2 SECs operative

Question 16

Breaking modes

Answer 16

‐ Normal braking
‐ Alternate braking with antiskid
‐ Alternate braking without antiskid
‐ Parking brake

Question 17

What can the accumulator supply?

Answer 17

• 7 full brake applications, or

- parking pressure for at least 12 h

Question 18

When is the landing gear safety valve activated

Answer 18

Above 260 knts hydraulic supply is cut off from the landing gear system