Wheels tyres and brakes Flashcards
The air in a tyre can be contained in 2 ways. What are they?
Tubed
tubeless
What is the ply rating of a tyre?
Indication of the tyre’s strength
What is tread for?
Adds grip by expelling water, usually ribbed type.
What is a re-tread?
Bonding a new tread pattern to a worn tyre
What is tyre creep?
Movement of the tyre around it’s rim. Caused by it’s raid acceleration on landing.
How is type creep monitored?
Creep marks. Overlapping is good.
What is a tyre limiting speed?
Structure only able to withstand a limited amount of ground-rolling forces
What do cuts and excessive wear do?
Increase the risk of a tyre burst. Check the wear indicators are within limits.
What pop to release tyre pressure if it becomes excessive?
Thermal (fusible) plugs
Reasons to reject a tyre: (8)
Significant cuts
Bulges
Flat spots
FOD
Contamination
Excessive Creep
Excessive wear
over/under inflated
Describe a disc brake
A hydraulically operated calliper, lined with break pads, clamps onto a disc bolted on to the wheel. Friction slows the wheel
What are the brakes made of in light aircraft and how are they operated?
Steel discs
Calliper is operated by two or three hydraulic pistons
What brake components are duplicated in a large aircraft?
discs
circular pressure plates
piston clamp assemblies
How does the 787 differ on the break front?
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.
Carbon is good because
Carbon is lighter and has a higher operating temperature limit, better coefficient of friction and wears less.
Hot brakes lose their ability to generate friction this is known as
brake fade
What is the purpose of a brakes?
Convert kinetic energy to heat
What shows the level of brake wear?
brake wear indicator pins
On a hydraulic braking system find emergency break pressure from which component?
Brake accumulator
Anti-skid: how does that work?
Sensors measure wheel rotation and compare the results.
It can then reduce / remove brake pressure
What can anti-skid do to the breaking performance? How often does it operate.
Potentially half it
It operates many times a second.
Which protection also offers touchdown protection? What do it do?
Anti-skid
Releases pressure to the brakes before touchdown.
Auto-brake requires which system to be operational
Anti-skid
When is auto-break deactivated?
TOGA applied on landing
Break pedals touched.
