Wheels tyres and brakes

Question 1

The air in a tyre can be contained in 2 ways. What are they?

Answer 1

Tubed
tubeless

Question 2

What is the ply rating of a tyre?

Answer 2

Indication of the tyre’s strength

Question 3

What is tread for?

Answer 3

Adds grip by expelling water, usually ribbed type.

Question 4

What is a re-tread?

Answer 4

Bonding a new tread pattern to a worn tyre

Question 5

What is tyre creep?

Answer 5

Movement of the tyre around it’s rim. Caused by it’s raid acceleration on landing.

Question 6

How is type creep monitored?

Answer 6

Creep marks. Overlapping is good.

Question 7

What is a tyre limiting speed?

Answer 7

Structure only able to withstand a limited amount of ground-rolling forces

Question 8

What do cuts and excessive wear do?

Answer 8

Increase the risk of a tyre burst. Check the wear indicators are within limits.

Question 9

What pop to release tyre pressure if it becomes excessive?

Answer 9

Thermal (fusible) plugs

Question 10

Reasons to reject a tyre: (8)

Answer 10

Significant cuts
Bulges
Flat spots
FOD
Contamination
Excessive Creep
Excessive wear
over/under inflated

Question 11

Describe a disc brake

Answer 11

A hydraulically operated calliper, lined with break pads, clamps onto a disc bolted on to the wheel. Friction slows the wheel

Question 12

What are the brakes made of in light aircraft and how are they operated?

Answer 12

Steel discs
Calliper is operated by two or three hydraulic pistons

Question 13

What brake components are duplicated in a large aircraft?

Answer 13

discs
circular pressure plates
piston clamp assemblies

Question 14

How does the 787 differ on the break front?

Answer 14

Each assembly houses 4 actuators and motors

The motor torque proportionally applies pressure via the actuator to squeeze the assembly

Temperature sensors alter brake pressure in response to temperature to allow for thermal expansion/contraction.

Question 15

Carbon is good because

Answer 15

Carbon is lighter and has a higher operating temperature limit, better coefficient of friction and wears less.

Question 16

Hot brakes lose their ability to generate friction this is known as

Answer 16

brake fade

Question 17

What is the purpose of a brakes?

Answer 17

Convert kinetic energy to heat

Question 18

What shows the level of brake wear?

Answer 18

brake wear indicator pins

Question 19

On a hydraulic braking system find emergency break pressure from which component?

Answer 19

Brake accumulator

Question 20

Anti-skid: how does that work?

Answer 20

Sensors measure wheel rotation and compare the results.

It can then reduce / remove brake pressure

Question 21

What can anti-skid do to the breaking performance? How often does it operate.

Answer 21

Potentially half it
It operates many times a second.

Question 22

Which protection also offers touchdown protection? What do it do?

Answer 22

Anti-skid
Releases pressure to the brakes before touchdown.

Question 23

Auto-brake requires which system to be operational

Answer 23

Anti-skid

Question 24

When is auto-break deactivated?

Answer 24

TOGA applied on landing
Break pedals touched.