Landing gear

Question 1

Which hydraulic system is used for normal braking?

Answer 1

Normal braking uses the green hydraulic system.

Question 2

Which hydraulic system is used for alternate braking?

Answer 2

Alternate braking uses the blue hydraulic system.

Question 3

What controls and monitors the normal braking system?

Answer 3

The normal braking system is controlled and monitored by the Braking Steering Control Unit (BSCU) with Anti-Skid.

Question 4

What controls and monitors the alternate braking system, and what happens if it is lost?

Answer 4

The alternate braking system is controlled and monitored by the Braking Steering Control Unit (BSCU) with Anti-Skid. If the BSCU is lost, Anti-Skid is also lost.

Question 5

Which hydraulic system is used for landing gear extension and retraction?

Answer 5

The green hydraulic system is used for landing gear extension and retraction.

Question 6

How many Landing Gear Control and Interface Units (LGCIUs) are there?

Answer 6

There are two LGCIUs.

Question 7

What sensor does the Braking Steering Control Unit (BSCU) use for data?

Answer 7

The BSCU uses data from the wheel tachometer.

Question 8

Which hydraulic system powers the steering?

Answer 8

The steering is powered by the green hydraulic system.

Question 9

Where is the H dimension placard located?

Answer 9

The H dimension placard is located on the main strut.

Question 10

How is the main strut depressurized?

Answer 10

The main strut is depressurized via a removable plate on the upper main strut.

Question 11

What powers the landing gear pitch trimmer, and what is its function?

Answer 11

The landing gear pitch trimmer is powered by the green hydraulic system. It maintains the geometry of the links during retraction, take-off, and landing.

Question 12

What mechanism helps retract the landing gear by pulling the entire strut up?

Answer 12

A shortening mechanism installed at the top of the strut pulls the entire strut up into the gear for retraction.

Question 13

Which hydraulic system powers the landing gear doors?

Answer 13

The landing gear doors are powered by the green hydraulic system.

Question 14

How are the normal brakes supplied with green hydraulics?

Answer 14

The normal brakes are supplied with green hydraulics via a normal selector valve and a normal servo valve.

Question 15

How does the braking system determine whether to use normal or alternate braking?

Answer 15

An automatic selector in the braking system selects normal or alternate braking depending on available hydraulic pressure.

Question 16

Where is alternate braking displayed?

Answer 16

Alternate braking is shown on the triple indicator.

Question 17

What function does the alternate servo valve provide if the BSCU is still functioning?

Answer 17

The alternate servo valve acts as anti-skid but powers two wheels at once.

Question 18

How many full brake applications can be made using the accumulators?

Answer 18

You can get 7 full applications of the brakes from the accumulators.

Question 19

What happens to other braking modes when the parking brake is selected?

Answer 19

When the parking brake is selected, the BSCU inhibits all other braking modes.

Question 20

What type of system is used for gravity extension?

Answer 20

Gravity extension is a motor-driven system.

Question 21

What condition must be met to perform a brake indicator check?

Answer 21

The parking brake must be set for a brake indicator check.

Question 22

How many times can a spare strut seal changeover be performed?

Answer 22

A spare strut seal changeover can be carried out once.

Question 23

What is contained in the upper part of the main landing gear (MLG) strut?

Answer 23

The upper part of the MLG strut contains nitrogen with oil below it, while the lower part is just a sliding tube.

Question 24

What is contained in the nose landing gear (NLG) strut?

Answer 24

The NLG strut has nitrogen in the upper and lower parts with oil in the middle.

Question 25

How are the Landing Gear Control and Interface Units (LGCIUs) powered, and how do they function?

Answer 25

Both LGCIUs are continuously electrically supplied, but only one is active at a time and controls the extension/retraction sequence.

Question 26

What do the green and red triangles on the landing gear indicator represent?

Answer 26

A green triangle indicates the associated gear is down and locked, while a red triangle means the gear is not locked, either up or down.

Question 27

What is the function of the Isolation Safety Valve in the landing gear system?

Answer 27

The Isolation Safety Valve de-energizes closed when the airspeed is greater than 280 knots, isolating the landing gear system from the green hydraulic system.

Question 28

What functions does the dual-channel BSCU control?

Answer 28

The dual-channel BSCU controls normal, manual, and auto braking systems with anti-skid protection.

Question 29

What is the purpose of the return accumulator in the landing gear system?

Answer 29

The return accumulator (one per gear) prevents pressure spikes in the return line when the brakes are released.

Question 30

How does the BSCU activate the normal braking selector valve in manual braking mode?

Answer 30

In manual braking mode, brake pedal deflections are converted into a voltage by the brake pedal transmitter unit and sent to the BSCU. If the deflection exceeds 2 degrees, the BSCU energizes the normal braking selector valve.

Question 31

When does the green DECEL light illuminate while auto brake is engaged?

Answer 31

The green DECEL light illuminates when 80% of the required rate of deceleration is achieved.

Question 32

What conditions must be met for Auto Braking to be active?

Answer 32

Auto Braking requires green hydraulics, no BSCU failure, at least 2 PRIMs, and one ADIRU available.

Question 33

Which braking system is used for Auto Braking?

Answer 33

Auto Braking is achieved via the normal braking system.

Question 34

How can you confirm if anti-skid is currently active on the SD wheel page?

Answer 34

Anti-skid is active if 3 green bars are displayed on the SD wheel page.

Question 35

Where are the two alternate brake accumulators located?

Answer 35

They are located forward of the main landing gear bay.

Question 36

How are the brake accumulators charged, and what features do they have?

Answer 36

The brake accumulators are charged from the blue hydraulic ground service panel, and each has its own gauge and inflating valve.

Question 37

Where are the pressure gauges for servicing the brake accumulators located?

Answer 37

Two pressure gauges are provided on the blue ground service panel for the correct servicing of the accumulators.

Question 38

What component provides parking brake pressure to the triple indicator?

Answer 38

Alternate Brake Pressure Transducers are installed on each MLG to provide parking brake pressure to the triple indicator.

Question 39

How long does the accumulator pressure allow parking brake application?

Answer 39

The accumulator pressure allows parking brake application for 12 hours.

Question 40

What are the three sources of steering command inputs?

Answer 40

1- The handwheel 2- The rudder pedals 3- Autopilot guidance orders

Question 41

How many internal systems does the BSCU have, and what are their functions?

Answer 41

The BSCU has two independently supplied internal systems, both of which control and monitor steering.

Question 42

What is the maximum steering angle with the handwheel when the aircraft speed is less than 40 knots?

Answer 42

72 degrees at speeds less than 40 knots.

Question 43

What is the maximum steering angle with the rudder pedals, and at what speed is it available?

Answer 43

6 degrees at speeds less than 100 knots. (sent to the BSCU via PRIM 1, 2 & 3)

Question 44

What happens to the steering angle as airspeed increases?

Answer 44

The steering angle decreases

Question 45

What happens when the pedal disconnect pushbutton on the handwheel is pressed?

Answer 45

Steering via the rudder pedals is disconnected.

Question 46

What mechanism centres the NLG wheels when fully extended in flight?

Answer 46

Two cams drive the wheels to the centre position.

Question 47

What connects the hydraulic lines to the two steering actuators?

Answer 47

Rotating selector valves.

Question 48

What happens to the nose wheels in the case of total BSCU or hydraulic failure?

Answer 48

The nose wheels can castor in the direction of aircraft travel, and shimmy damping remains the same as a fully powered system.

Question 49

What is the maximum towing angle of the aircraft?

Answer 49

65 degrees.

Question 50

At what towing angle do the proximity sensors indicate exceedance?

Answer 50

93 degrees.