Brakes

Question 1

What is the purpose of the brakes?

Answer 1

To convert kinetic energy into heat energy

Question 2

Braking performance is mainly limited by

Answer 2

The ability to dissipate heat (if too hot, brakes become less effective)

Question 3

Is differential braking possible on large jet aircraft?

Answer 3

Yes, but it is not usually used unless the nose gear can caster (like the DA40).

Question 4

Why is the anti-skid system so important?

Answer 4

Because pilots ultimately have no ‘feel’ of the brakes, because their inputs are hydraulically applied.

Question 5

Does the anti-skid system operate each wheel individually or each gear?

Answer 5

Each wheel! Every wheel will have a hydraulic line attached to the brake, and therefore a modulator will be fitted which prevent skidding.

Question 6

What are the 5 purposes of the anti-skid system?

Answer 6

Skid protection, locked wheel protection, touchdown protection (accidentally landing with brakes on), hydroplane, and failsafe protection (won’t let tyres lock).

Question 7

To what point does the anti-skid system let wheels get in relation to skidding?

Answer 7

Verge of skidding but not actually skidding

Question 8

What is a lockout valve?

Answer 8

Ultimately protects you from losing all your brakes. If a leak is detected in the line, a valve will close, and only oil downstream of the valve will be lost.

Question 9

How do alternate brakes work?

Answer 9

If the primary hydraulic system is lost, then the same brake pedals are supplied, but this time different hydraulic fluid via a shuttle valve will be used to depress the brake pads.

Question 10

What is the concept of auto-brakes?

Answer 10

Depending on the level (rate of deceleration) you select, the system will automatically brake for you.

Question 11

As the aircraft slows down using auto-brakes, is the brake pressure increased or decreased?

Answer 11

brake pressure is increased to maintain the same rate. If it stayed the same, then the aircraft would not maintain the same rate.

Question 12

When reverse thrust is used in conjunction with auto-brakes, is the brake pressure increased or decreased?

Answer 12

Decreased, because the reverse thrust is doing some of the work.

Question 13

How long will the auto-brake system stay active?

Answer 13

Until fully stopped or disarmed.

Question 14

What is the purpose of the auto-brake shuttle valve?

Answer 14

Isolates auto-brake or brake pedal pressure. If auto-brake is armed, then the brake pedal pressure is isolated. If the pilot steps on the brakes, the shuttle valve switches and now the auto-brake system is isolated (no longer armed)

Question 15

What are the levels of auto-brake, and when are they used?

Answer 15

1-2, normal dry runway
2-4, wet/icy runway
5, max braking (emergency)

Question 16

If you need to stop in the shortest distance possible, would you use auto-brake or manual braking?

Answer 16

Manual braking (stronger than level 5 auto-brake) if you are landing, but auto-brake if it is a RTO.

Question 17

What pilot actions would terminate the auto-brake system?

Answer 17

Manual input on the brake pedals, disarming the system, retracting the speed brakes on the ground, and increasing thrust after idle (e.g. RTO).

Question 18

What is automatic retraction braking?

Answer 18

If the pilot applies brakes while the wheels are being retracted, then gyroscopic forces can cause damage, so this system will stop the wheels spinning before gear is retracted.

Question 19

What is the firewire?

Answer 19

When temperatures within the wheel well exceed a specified valua, a warning light will illuminate. Crews will then have to extend the gear in the hopes of the slipstream extinguishing the fire as there is no extinguish system attached.

Question 20

What are fusible plugs?

Answer 20

Plugs that will melt at high temperatures and deflate the tyres to prevent explosion.

Question 21

Where are thermal fuse (fusbile) plugs fitted?

Answer 21

The inner wheel.

Question 22

What does the brake pressure gauge monitor?

Answer 22

Accumulator pressure, NOT the pressure being applied to the brakes.