Tyre Construction - Wheels & Tyres - Airframes & Aircraft Systems #20

Summary

This educational video script delves into the construction of aircraft tires, focusing on radial and cross ply types. It explains the function of tire components like the crown, shoulder, and sidewall, and the significance of tire inflation with nitrogen. The script distinguishes between radial ply and bias tires based on cord arrangement. It also covers tire ratings, bead construction, and the importance of correct tire pressure for aircraft safety. Additionally, it touches on special features like breaker strips and chines for water dispersion, emphasizing the need for various tire sizes and pressures to accommodate different aircraft landing speeds and surfaces.

Takeaways

• 🛫 Aircraft tires are crucial for absorbing shocks and supporting the weight of the aircraft during landing and takeoff.
• 🌐 There are two main types of aircraft tires: radial and cross ply (bias) tires, differing in their construction methods.
• 💭 Modern aircraft mostly use tubeless tires, while some light and older aircraft may use tires with inner tubes.
• 🔍 Tires are inflated with nitrogen to enhance their performance and durability.
• 🔩 The tire is divided into sections: crown, shoulder, sidewall, and bead, each playing a specific role in the tire's function.
• 🌀 Radial tires have cords that run from bead to bead at approximately 90 degrees to the centerline, enhancing their strength and performance.
• 🔄 Bias or cross ply tires have cords arranged at 90 degrees to one another in adjacent plies, providing a different structural integrity.
• 🏷 The ply rating on a tire indicates its strength and is displayed on the sidewall, but it does not directly correspond to the number of plies.
• 🔩 Tire beads, made of high tensile wire strands, are crucial for holding the tire onto the wheel and maintaining a gas-tight seal if tubeless.
• 💧 Tread patterns, such as ribbed types with circumferential grooves, aid in water dispersion and prevent aquaplaning, improving grip on runway surfaces.
• ⚙️ Special breaker strips in some tires provide additional strength and support, especially under heavy loads or high-speed operations.

Q & A

What are the two types of tires fitted to aircraft?

The two types of tires fitted to aircraft are radial and cross ply or bias tires.

What type of tires are most modern aircraft equipped with?

Most modern aircraft are equipped with tubeless tires.

What gas is commonly used to inflate aircraft tires and why?

Nitrogen is commonly used to inflate aircraft tires because it absorbs shocks and supports the weight of the aircraft.

What is the function of the tire cover in an aircraft tire?

The tire cover maintains the shape of the tire, transmits braking, and provides a wearing surface.

What are the two main sections of a tire and what are their roles?

The two main sections of a tire are the crown and the shoulder section. The crown bears the load and provides a contact surface with the ground, while the shoulder section provides additional support and helps maintain tire shape.

How are the cords in bias or cross ply tires arranged during tire construction?

In bias or cross ply tires, the cords of adjacent plies are arranged at 90 degrees to one another and from bead to bead at approximately 90 degrees to the centerline of the tire.

What does the ply rating of a tire indicate?

The ply rating of a tire does not directly relate to the number of plies but is an index of the tire's strength.

What is the purpose of the rubber lining applied to the inner surface of a tubeless tire?

The rubber lining in a tubeless tire retains the gas pressure and forms a gas-tight seal on the wheel rim.

What is the function of breaker strips in aircraft tires?

Breaker strips are narrow plies embedded in thick layers of rubber between the casing and the tread to provide additional strength and protection against damage.

Why are chines molded onto the shoulder of nosewheel tires?

Chines are rubber extensions designed to direct water away from engine intakes, preventing flameouts due to water ingestion.

What is the importance of checking tire inflation pressure in aircraft?

Checking tire inflation pressure is crucial as incorrect pressure can lead to tire failures. Under-inflated tires may cause excessive shoulder wear and creep, while over-inflated tires can cause excessive wear to the crown of the tires.

Outlines

00:00

🛫 Aircraft Tire Construction and Types

This paragraph introduces the two types of tires used in aircraft: radial and cross ply or bias. It explains the function of pneumatic tires, which are either tubeless or have an inner tube, with modern aircraft typically using tubeless tires. The paragraph details the various parts of a tire, including the crown, shoulder, tread, sidewall, and bead. It also discusses the construction of tires, highlighting the arrangement of cords in the casing and the difference between radial ply and bias or cross ply tires. The importance of tire ratings, bead construction, and the use of rubber lining in tubeless tires are also covered. Additionally, the paragraph touches on the role of breaker strips and tread patterns, emphasizing the ribbed type for water dispersion and improved grip. Special features like chines on nosewheel tires are mentioned to prevent water ingestion and engine flameouts.

05:03

🔍 Tire Inflation, Pressure Groups, and Maintenance

The second paragraph delves into the specifics of tire inflation, emphasizing the use of nitrogen or inert gases with less than 5% oxygen content to maintain correct tire pressure. It categorizes tires into four pressure groups: low, medium, high, and extra high pressure, each designed for different types of runway surfaces. The paragraph underscores the importance of proper inflation to prevent tire failure, with 90% of failures attributed to incorrect gas pressure. It also mentions the potential for real-time tire pressure monitoring on modern aircraft and the manufacturer-specified maximum ground speed for tires. The summary concludes with a reminder of the significance of tire ply ratings as an indicator of strength rather than the number of plies and the effects of under and over inflation on tire performance and longevity.

Keywords

💡Aircraft Tires

Aircraft tires are specialized pneumatic tires designed to withstand the extreme conditions of flight, particularly the high speeds and heavy loads experienced during takeoff and landing. They are crucial for the safe operation of aircraft, providing shock absorption, weight support, and traction. The script discusses two types of aircraft tires: radial and cross-ply (bias), highlighting their construction and functionality.

💡Radial Ply Tires

Radial ply tires are a type of aircraft tire construction where the cords in the tire plies run radially from the bead to the tread. This design offers greater strength, flexibility, and durability compared to cross-ply tires. The script mentions that radial tires are given a ply rating by the manufacturer, which is an index of the tire's strength rather than the number of plies.

💡Cross Ply or Bias Tires

Cross ply or bias tires are another type of aircraft tire construction where the cords in the plies are laid at a bias angle, typically around 35 to 40 degrees, to the centerline of the tire. This results in a stronger tire with good load-carrying capabilities, though they are generally heavier and less flexible than radial tires.

💡Tire Bead

The tire bead is the part of the tire that seats inside the wheel flange and holds the tire securely onto the wheel. It is made of high tensile wire strands coated with rubber compound and is crucial for maintaining the tire's structural integrity and ensuring a proper seal with the wheel. The script explains that the beads are spiral-wound into a coil of specified diameter for the tire.

💡Tire Cord

Tire cords are the reinforcing materials, often made of cotton, rayon, or nylon, that provide strength to the tire. They are arranged in parallel layers within the tire casing and are crucial for the tire's ability to withstand the forces experienced during flight. The script notes that these cords are not woven but are arranged in single layers with rubber to prevent them from cutting one another as the tire flexes.

💡Tread

The tread of a tire is the part of the tire that comes into contact with the ground during use. It is designed to provide traction,耐磨性, and to disperse water to prevent aquaplaning. The script describes the tread as being either plain and smooth or molded in a block pattern, with the ribbed type being the most popular for its water dispersion and grip benefits.

💡Sidewall

The sidewall of a tire is the part that connects the tread to the bead and allows for flexibility and bending as the tire rolls. It is also where various markings, such as size and pressure ratings, are found. The script highlights the importance of the sidewall in maintaining the tire's shape and flexibility.

💡Inflation Pressure

Inflation pressure refers to the amount of air pressure inside a tire. The script discusses how aircraft tires are categorized into low, medium, high, and extra high-pressure groups, with each type designed for specific landing gear surfaces and conditions. Correct inflation pressure is essential for tire performance and safety.

💡Nitrogen Inflation

Nitrogen is often used to inflate aircraft tires due to its inert properties, which help maintain consistent pressure and reduce the risk of tire failure. The script mentions that tires are usually inflated with nitrogen to absorb shocks and support the aircraft's weight.

💡Tire Failure

Tire failure can occur due to various factors, including incorrect inflation pressure, excessive wear, or damage. The script emphasizes that approximately 90% of tire failures can be attributed to incorrect gas pressure, with overinflation leading to excessive wear on the tire's crown and underinflation causing shoulder wear and creep.

💡Max Ground Speed

The maximum ground speed is the highest speed at which a tire can be safely operated without risking damage. This speed is set by the manufacturer and marked on the tire. The script warns that exceeding this speed can lead to damage, including possible tread separation.

Highlights

Aircraft tires come in two types: radial and cross ply or bias.

Aircraft wheels are fitted with pneumatic tires, which can be tubeless or have an inner tube.

Most modern aircraft use tubeless tires inflated with nitrogen for shock absorption and weight support.

The tire cover maintains the tire's shape, transmits braking, and provides a wearing surface.

Tires are divided into regions: crown, shoulder, sidewall, and bead.

The term 'tread' applies to both plain and block pattern rubber.

Bias or cross ply tires have cords arranged at 90 degrees to one another.

Radial tires have cords running from bead to bead at approximately 90 degrees to the centerline.

Tire ply rating is an index of tire strength, not directly related to the number of plies.

Tire beads are made of high tensile wire strands coated with rubber and spiral-wound into a coil.

For tubeless tires, a rubber lining is applied to the inner surface for a gas-tight seal.

Breaker strips are narrow plies embedded in rubber to protect the casing from damage.

Ribbed tread patterns are popular for water dispersion and to prevent aquaplaning.

Nosewheel tires may have chines to direct water away from engine intakes, preventing flameouts.

Inflation valves are required for both tubed and tubeless tires, with a non-return valve and valve cap for safety.

Tires are categorized into low, medium, high, and extra high-pressure groups based on inflation pressures.

Incorrect gas pressure is estimated to cause 90% of tire failures.

Real-time tire pressure monitoring is available on some modern aircraft.

Tire ply rating indicates strength, not the number of plies, and is marked on the sidewall.

Aircraft tires must be kept inflated to the correct pressure to prevent under or over-inflation issues.

Transcripts

in this the first of two lessons on

aircraft tires the construction of the

two types of tire fitted to aircraft

radial and cross ply or bias will be

described

aircraft wheels are fitted with

pneumatic tires which may be tubeless or

have an inner tube

tires fitted with inner tubes tend to be

used on some light aircraft and on older

aircraft most modern aircraft have two

'bless tires fitted

tires are usually inflated with nitrogen

which absorb shocks and supports the

weight of the aircraft while the tire

cover maintains the shape of the tire

transmits braking and provides a wearing

surface

if a tube is fitted the tire also

restrains the tube and protects it from

damage

you

the tire is divided into regions or

sections as illustrated here

the tire is situated in the crown and

shoulder section

it is worth noting that the term tread

is applied irrespective of whether the

rubber is plain and smooth or molded on

a block pattern

the sidewall allows the tire to be

flexible

and the bead is seated inside the flange

of the wheel

there are two types of tire in common

use these are known as radial ply and

bias or cross ply tires the names

originating from the way the tires are

constructed

the tire consists of a casing made of

plies of cotton rayon or nylon cords the

cords are not woven but arranged

parallel in single layers and held

together by a thin film of rubber which

prevents cords of adjacent plies from

cutting one another as the tire flexes

in use during construction of the tire

the plies are fitted in pairs and set

out so that the cords of adjacent plies

are at 90 degrees to one another in the

case of bias or cross ply tires

and from bead to bead at approximately

90 degrees to the centerline of the tire

in radial tires

the tire manufacturer gives each tire

apply rating

this rating does not relate directly to

the number of plies in the tire but is

the index of the strength of the tire

the ply rating is shown on the sidewall

of the tire

this tie for example has apply ratings

32 but it only has 18 plies

the tire beads hold the tire on its

wheel the beads are made of high tensile

wire strands

each wire strand is coated with rubber

compound and is spiral-wound into a coil

of the specified diameter for the tire

the plies are wrapped around the beads

and turned out back on to themselves

if the tire is designed to be used

without an inner tube a rubber lining is

applied to its inner surface and the

underside of the beads

this lining which retains the gas

pressure forms a gas tight seal on the

wheel rim

the cows seal depends on a wedge fit

between the underside of the tyre bead

and the taper of the wheel rim

to absorb and distribute load shocks and

protect the casing from concussion

damage some tires have to narrow plies

embedded in thick layers of rubber

between the casing and the tread

these special prize are termed breaker

strips

the most popular tread pattern is the

ribbed type it is formed from

circumferential grooves around the tire

to assist in water dispersion and to

help prevent aquaplaning or hydroplaning

the grooves also help to improve contact

grip between the tread and the runway

surface

nosewheel tires particularly those

fitted to aircraft with the engines

mounted on the rear fuselage may have a

chine or chines molded onto the shoulder

these a rubber extensions

designed to direct water away from the

engine intakes and so prevent flameouts

due to water ingestion

a nosewheel tire fitted to a single

wheel installation will have a chine

moulded onto both sides of the tire

whilst on a double nosewheel

installation the Chinese fitted only to

the outer edge of each tire

whether the chair is fitted with a tube

or is tubeless an inflation valve is

required

in the case of the tire with a tube the

vowel forms part of the tube

installation

on a tubeless tire it is fitted directly

onto the wheel rim with a rubber sealing

gasket

each inflation valve is fitted with a

non-return valve

the valve core is not considered to be a

perfect seal therefore the inflation

valve must always be fitted with the

valve cap

the valve cap also prevents dirt from

entering the valve

it is important when doing your external

check the aircraft that you check that

the valve caps which are normally

colored yellow are fitted

they will slow down the loss of pressure

in the event of a valve failure

the differences in landing speeds

loading landing gear surfaces and

landing gear construction of aircraft

make it necessary to provide a wide

range of tire sizes types of tire

construction and inflation pressures

in terms of inflation pressures ties a

split into four main groups identified

as low medium high and extra high

pressure tires

low pressure tires are designed to

operate at a pressure of 25 to 35 pounds

per square inch psi or 1.73

to 2.4 to bar

these are fitted to aircraft using grass

surfaces for takeoff and landing

medium pressure tires operate at a

pressure of 35 to 70 psi or 2.4 to 24.8

3 bar and are used on grass surfaces or

on medium firm surfaces without a

consolidated base

I pressure tires operated a pressure of

70 to 90 psi or four point eight three

to six point two one bar and is suitable

for concrete runways

extra high-pressure tires are fitted to

most large modern airliners

they operate at pressures of over 90 psi

with some ties of this type being

inflated to 350 psi or 24.2 bar

these tires are suitable for concrete

runways

tires in use must be kept inflated to

the correct pressure using nitrogen or

another inert gas with less than 5%

oxygen content as under inflated tires

may move or creep around the wheel and

overinflated tires will cause other

types of failure

it is estimated that 90% of all tire

failures can be attributed to incorrect

gas pressure over inflation will cause

excessive wear to the crown of the tires

whilst under inflation is the cause of

excessive shoulder wear and creep on

some modern aircraft real-time tire

pressures can be displayed on the flight

deck as shown here on this a320

electronic display screen

the manufacturer will set a maximum

ground speed to which a tire can be

subjected this will be marked on the

side of the tire

it is important that this speed is not

exceeded as damage including possible

tread separation may occur

you should now have an understanding of

how the two types of tire are

constructed

bear in mind that the prior rating of

attire is not necessarily an indication

of the number of plies it is an

indication of the ties strength

you also need to be aware of the effects

of both under and over inflation of

tires