Cap 7 Wheels Tyre And Brakes

Question 1

Type of tyres

Answer 1

Ply rating> indicate tyre strength
Tread> rubber
Tubeless> internally airtight,no inner tube
Bias> plies laid in pairs ,adjacent at 90 degress
Radial >plies are laid from bead to bead
Retread > new treat heat bonded onto old carcass
Tubed tyres> use an inner tube with an infaltion valve

Question 2

Tyre creep

Answer 2

Sudden acceleration cause the tyre to slip around the wheel.
1 inch wide for tyres of 24incg or less
1.5 inch wide for tyres over 24 diameter

Creep in monitored with creep marks

Question 3

Tyres speed rating

Answer 3

~often rated in MPH
Tyre speed rating must match /exceed the maximum anticipated ground rolling speed of the a/c

Exceeding tyre limits>
~excess tyre heat
~excess tyre stress that damages or destroys the tyre

Question 4

Tyres wear

Answer 4

Ribbed treads»
~min tread depth is 2mm
~may have a wear marker
~tyre is on its limit when marker is at the same height as the rib

Blocked treads»
~within limits provided that the block pattern is still visible

Question 5

Tyre inspect

Answer 5

~damage or under inflation can lead to tyre failure or tread separation
~a burst tyre can result in loss of control
~if a tyre breaks up during use it can cause serious damage to the a/c

Question 6

Tyre inspection

Answer 6

~Cuts>any cut the cords or sidewall require tyre replacemnt
~bulges > indicates tyre structure weaken 
~flat spots>excessive wear
~FOD>
~contamination 
~creep
~wear
~pressure

Question 7

Tyre pressues

Answer 7

Large a/c»
Low pressure: up to 200psi
High pressure : 200-315 psi

Question 8

Tyre overheat protection

Answer 8

Fusible plug

Question 9

Wheel brakes

Answer 9

Light a/c >use single disk types
Large> mulitple disk pack systems

Some a/c are equipped with a brake wear indicator pin when it goes further in means brakes are wear (brakes need to be applied to check)

Question 10

Wheel brakes

Answer 10

Fixed disk - Floating calliper

Floating disk - fixed calliper

Question 11

Large brake systems (multiple disc brakes)

Answer 11

The rotor segment is physically engaged with the wheel assembly via the torque tube and so rotates with the wheel

Series of pads are arranged concentrically around both sides of a stator assembly

In between each pair of stators is a rotor segment

Question 12

Automatic brake sys adjuster

Answer 12

Ensures correct clearance between the rotating assemblies when the brakes are in the off position

Question 13

Brake wear indicator pin

Answer 13

When brake pads worn the pin starts to retract into the housing

Question 14

Carbon braking advantages and disadvantages

Answer 14

Advantages>
Lighter
Absorbs twice as much heat as steel
Less prone to brake fade
Carbon brakes last longer
30% to 175% improvement 

Disadvantages > more expensive

Question 15

Heat dissipation

Answer 15

Large transport a/c equipped with brake fan units
May specify a min brake hold over time to allow cooling between landing
ATC must be informed in event of brake overheat

Question 16

Brake tenmp indication

Answer 16

Displays the hottest brake temp

Displayed on ECAM or EICAS

Question 17

ANTI SKID SYS

Answer 17

CONTROLLER determines if a wheel is going to stop rotating due to high braking and it releases some of the pressure to make it rotate and then reaply at lower pressure.

“Slip ration “the theoretical un-braked (idler) wheel and the braked wheel

Question 18

Anti skid sys does

Answer 18

Touchdown protection
Incorporate a touch down protection feature:
Prevents brake pressue being applied at the wheel before touch down .

And BOUNCE PROTECTION is a protection when the wheels bounce after touch down and release the brakes until it starts to spin again ,onky then brake is reapplied

HYDROPLANE PROTECTION: as touchdown or bounce protection,
Waits until the tyre start to rotate to apply brakes.

Braking without anti skidding will double the landing distance

Question 19

Autobraking

Answer 19

Autobrake> must be ON
ANTI SKID > MUST BE ON and servicible
power levers> must be set below a a certain value
Hydraulic sys> must befunctional
Brake pedals > must be depressed while turning ON the autobrake sys

Question 20

RTO

Answer 20

Provides max braking ,it activities only:
~speed greater than 90 kts
~Thrust levers idle
~touching the brakes will disarm as for the AUTOLAND

Question 21

Emergency braking sys

Answer 21

No anti skid is available

And limited braking applications with in emergency mode (6 applications)

Question 22

The parking brake

Answer 22

Brake pressure to the wheel to be applied and held.

Overrides all other braking systems including :
Anti skid
Touch down protection