typres

Question 1

aircraft wheels are fitted with which tyres

Answer 1

pneumatic tyres

Question 2

types of pneumatic tyres

Answer 2

Tubes (light or older aircrafts)

Tubeless

Question 3

Tyres filled with?

Answer 3

Nitrogen

can support AC’s weight

good at absorbing shock

Question 4

tyre cover benefits

Answer 4

protects the tyre tube

transmits braking

provides a wearing surface

maintain shape of the tyre

Question 5

Tyre covers

Answer 5

Covers: made of rubber

Reinforced by Plies - cotton, nylon or rayon cores

Breaker strips

Question 6

What are breaker strips

Answer 6

**2 narrow plies* *embedded in thick rubber

between the casing and the tread

• absorbs shock
• protect from casing concussion
  *

Question 7

Plies cords

Answer 7

not woven

arranged in parralel in single layers and held by thin film of rubber to avoid chords cutting into each other

Question 8

Bias cross ply

Answer 8

plies fitted in pairs

chords set at 90 degrees angle to one another

Question 9

Radial tyres

Answer 9

plies fitted in pairs

chords set from bead to bead at approx 90 degrees to centre line of the tyre

Question 10

Bead

Answer 10

The casing is retained on the rim of the wheel by interlocking the plies around inextensible steel wire coils to form ply overlaps

wires are copper

rigidly bonding done between wire coils and the rubber

protected on the outside by chafer strips

Question 11

ply rating

Answer 11

index of tyre strength (not related to the # of plies in the typre)

Question 12

Tyre region - Crown & shoulder

‘tread’

Answer 12

This is where tread is located
**
tread has **ribbed patters/grooves

for:
1)assist in water dispersion
2)prevent acquaplaning
3)create contact/grip on the runway

Question 13

Diamond tread

Answer 13

used for all ‘weather patterns’ but not commonly used

Question 14

Nose wheel is fitted with?

Answer 14

Chine (moulded) in the shoulder area (sometimes on either side of the tyre)

usually for Aircraft with engines mounted in rear fuselage

it helps direct water away from engine intakes to avoid flameouts

Question 15

Braking and inner tubes

Answer 15

during breaking, excessive heat is generated

this can cause damage to standard inner tube

therefore the tube might have one of these reinforcement bases
- standard
- thickened
- cord

Question 16

when renewing the tube

Answer 16

must be replaced by the same tube type

Question 17

Inflation valve

Answer 17

it’s where the tube is inflated

infalation valve is vulcanized to the tube, therefore it cannot be renewed on its own

Question 18

Inflation valve anatomy

Answer 18

1) fitted with Scrader valve core (non-return valve)

2) The valve is not a perfect seal, so need inflation valve cap (also protects from dirt)

3) Schrader valve is a spring made of brass but stainless steel on modern ones

Question 19

Tubeless tyres

Question 20

Tyre size, construction and pressure need to accmmodate

Answer 20

• landing speed
• loading
• landing surfaces
• landing gear construction

Question 21

4 main categories of pressure

Answer 21

Low
25-35psi
for grass areas

medium
35-70psi
for grass and some medium firm surfaces

high
70-90psi
for concrete surfaces

Extra high
90+psi ..even to 350psi
for concrete surfaces

Question 22

Tyre contamination

Answer 22

Oil skin cover should be placed on the tyres to protect from:

**especially when parked **or when fluids are being replaced

• hydraulic fluid spills
• bright sunlight
• heat
• dampness
• oil, fuel, glycol

oil, glycol, hydraulic fluids must be wiped off immediately

Question 23

creep when tyres are first fitted

Answer 23

when tyres are first fitted to a while, they tend to move slightly around the wheel

this is normal and ceases after some time

Question 24

Creeping in Service

Answer 24

In service, the tyre may tend to continue to creep around the wheel.

Creep a tyre fitted with an inner tube:
- will tear out the inflation valve and cause the tyre to burst.

creep on tubeless tyre
- Creep is less of a problem with tubeless tyres, as long as the tyre bead is undamaged and any pressure drop is within limits.

Question 25

to prevent creep

Answer 25

mainain correct pressure

Underinflation causes creep

you can check via electonic system monitoring screen in the aircraft

Question 26

What is Rated Inflation pressure

Answer 26

Pressure specified by the manufacturer

this is based on a cold/unloaded tyre (when tyre not fitted to a plane

once fitted - increase that pressure by 4%

once it’s taxing, landing, taking off - increase that pressure by 10%

Question 27

what’s the tyre inflated with

Answer 27

Mainly nitrogen
other gases (maximum 5% Oxygen)

Question 28

Marking on tyres

Answer 28

1) ECTA/Conducting:
shows tyre has extra carbon in the rubber to conduct electricity (provide earthing between aircraft and ground)

2)Size on the sidewalls
Inside diameter - in
Outside diameter -in/ml
Nominal diameter - in/ml

3)ply rating on sidewalls
strength of tyre in ‘PR’

4)Green or Grey dots
Indicate the position of the AWL vent

5)red dot or triangle
indicate the lightest part of the typre
placed oppostie the valve
assist in balancing whieel assembly

6)DRR (in code panel) and ‘REINFORCED Tread’ in sidewall
indicative of the fact that the tyre has a layer of fabric woven into the tread which may become visible during normal wear. This layer must not be confused with the casing cords.

Question 29

Aquaplaning

Answer 29

caused by wedge of water building up under the tread, breaking contact with the ground

Aquaplaning speed is in NM / HR

=9 x Squar root of Tyre pressure in PSI

**if treat dept is reduced, aquaplan increases **

Question 30

what is MAT Limits

Answer 30

MAT = Mass, Altitude & Temperature

these may be altered to ensure they comply with the typres fitted

ex: when calculating take off distance with increased speed, it’s important to not exceed the speed rating of the tyres

Question 31

Tyre damages

Answer 31

Cuts
- replace if cuts show the cords

Bulges
- indicate partial failure of the casing
- Renew cover

**Foreign bodies
**- must not be removed and should be report to maintenance
- need to acertain depth of the cut

wear
replace if tread work to casing covering or
to the base of the marker groove

creep
-Movement of the tyre round the wheel must not exceed 1 in for tyres of up to 24 in outside diameter and 1½ in for tyres over 24 in outside diameter.
-typres must be removed
then tube is examined to see tearing of the valve
-if serviceable, tyre to be refitted and creep marks re-applied.

Treat separation
-when tread portion is detached from the tyre or Burst )this increases load on other tyres, reduce braking efficiency)

FOD - foreigh object damage
possibility of damage to brake hydraullic lines or debris in the engine

Question 32

to minimize the tyre wear, what’s the speed limit during taxi

Answer 32

40 km/hr
or 25m/hr

Question 33

overinflation causes wear in -

Answer 33

the crown

Question 34

underinflation caues wear in

Answer 34

the sholder

Question 35

Tubeless tyres characteristcs

Answer 35

1. Low heating
   with Tube tyres, they are at risk of high heating due to the friction between the tube and tyre
2. low valve fragility
   With tube tyres, the valve is connected to the tube and shear can damage the valve.
   In tubeless, the valve is connected to the rim so the valve & tyre and independent
3. lower risk of bursting (#1 & 2)