AGK Systems - Wheels, Tyres and Brakes

Question 1

What is Ply Rating?

Answer 1

Indicates tyre strength

Question 2

Tread

Answer 2

Rubber. Provides grip, expels water

Question 3

Tubless

Answer 3

Internally airtight, no inner tube. Lighter & runs cooler

Question 4

Bias (or cross-ply)

Answer 4

Plies laid in pairs. Adjacent at 90°

Question 5

Radial

Answer 5

Plies are laid from bead to bead

Question 6

Retread

Answer 6

New tread heat bonded onto old carcass

Question 7

Tubed Tyres

Answer 7

Use an inner tube with an inflation valve attached to it which is fed bout through a hole in the wheel

Question 8

What is Tyre Creep?

Answer 8

Only relevant for tubed tyres

Sudden accelerations cause the tyre to slip around the wheel

Creep is greatest just a tier a new tyre has been fitted. Excessive creep damages the inflation valve

Creep is monitored with creep marks

Question 9

Tyre Speed Rating

Answer 9

Often rated in MPH

It dictates the a/c tyre limiting speed on the ground (Vtyre)

Question 10

Low Pressure tyre

Answer 10

Up to 200psi

Question 11

High Pressure tyre

Answer 11

200-315psi

Question 12

Two types of braking systems…

Answer 12

Fixed Disk - Floating Calliper

Floating Disk - Fixed Calliper

Both use hydraulic pressure to clamp brake friction pads tightly against a steel disk

Question 13

Why is the caliper mounted on pins?

Answer 13

To allow for lateral movement known as ‘float’

Question 14

When do you check break wear indictors?

Answer 14

Only check them with the brakes applied

Question 15

Carbon Brake advantages/disadvantages

Answer 15

Adv

Lighter

Absorb twice as much heat as steel brakes

Carbon brakes last longer
~30%-175% improvement

Dis-adv

More expensive to fit but longer lifetime

Question 16

Should ATC be informed if you have hot brakes?

Answer 16

Yes

May put you on a remote stand as you are deemed dangerous as a tyre may explode. So they’d not want you near a terminal building

Question 17

Anti Skin System

Answer 17

Conroller knows how fast each wheel is spinning

When a wheel slows down, it knows its about to skid
~releases break pressure from that assembly to allow for maximum breaking efficiency

After this, the controller re applies the break break pressure slowly until it gets back to normal

Question 18

Touchdown Protection

Answer 18

Anti skid usually incorporates touchdown protection

Prevents break pressure being applied

Question 19

Bounce Protection

Answer 19

If the a/c bounces after touchdown, the system releases break pressure. This allows the wheels to spin up again before the second touchdown

Question 20

Spin down (t/o or landing)

Spin Up (When coming into contact with runway- locked)

Answer 20

9√P (psi) ==>kts

7.7√P (psi) ==>kts

Question 21

What is Hydroplanning

Answer 21

Hydroplanning is a result of built up water on the runway

If speed increases, the tyre is lifted off the surface

Results in:
Reduced or no breaking ability
Loss of directional control
Damage to tyres from superheated system

Question 22

Hydroplane Protection

Answer 22

Protection only on the rear wheels

Prevents the risk of locked rear wheels during touchdown

If gear is selected down and wheel speed is less than ground speed, the systems releases the break pressure on the rear wheel

Question 23

What happens if the Anti-Skid is inoperative

Answer 23

Landing distance can double

Amber warning caption illuminates if a fault is detected in the anti-skid system

Question 24

Automatic braking

Answer 24

No pilot input

Solenoid valve is energised after the wheels spin up

This valve feeds hydraulic pressure to the adaptive pressure control valves which adjust the amount of pressure fed to the break units

Question 25

Automatic braking settings

Answer 25

Setting 1 or MIN= Lowest level of retardation

Setting 3 or MAX= Highest level of retardation

Question 26

What are the prerequisites before auto braking can be armed?

Answer 26

Auto brake must be ON

Anti skid must be ON

Power levers must be set BELOW a certain value

Hydraulic system must be FUNCTIONAL

Brake pedals must be DEPRESSED

Question 27

How can auto braking be overriden?

Answer 27

Brakes are applied manually

Throttles set to TOGA power

Question 28

Rejected takeoff

Answer 28

RTO is a selection available during t/o

RTO provides max braking if following conditions are met:
~Speed greater than 90kts
~Thrust levers idle
~touching brakes will disarm system

Question 29

Emergency Braking System

Answer 29

All commercial a/c have an alternate hydraulic source for breaking

Emergency Brake Accumulator:
~consists of a break accumulator that provides up to 6 applications of brake if all hydraulic pressure is lost

Question 30

What are the Emergency Brake limitations?

Answer 30

No Anti Skid

No differential braking

Directional control problems

Usually a maximum of six applications (possible less)

Question 31

The Parking brake

Answer 31

Allows break pressure to the wheel to be applied & held

Set with parking break lever

Overrides ALL other breaking systems including:
~Anti Skid & Touchdown protection

For this reason, it should NEVER be set in flight

Question 32

How is the parking break set?

Answer 32

Set when the toe brakes are engaged

Question 33

When should the parking break not be set?

Answer 33

If your brakes are excessively hot