11.13 LANDING GEAR

Question 1

What are the 3 main landing gear (MLG) arrangements

Answer 1

• tail wheel
• tricycle-type
• Tandem

Question 2

Where is the aircraft’s CG positioned in a tricycle configuration

Answer 2

• ahead of main wheels

Question 3

Which configuration is uncommon

Answer 3

• Tabdem configuration

Question 4

When would you use fixed and retractable landing gear

Answer 4

Low speed aircraft - fixed
High speed aircraft - retractable

Question 5

What is the function of the MLG in terms of load

Answer 5

• transfers operational loads to the aircraft structure

Question 6

Explain the trunnion link

Answer 6

• connect top of leg to wing structure
• allows leg to rotate into and out of landing gear bay

Question 7

The shock strut has 2 telescopic cylinders known as

Answer 7

• outer and inner cylinder

Question 8

What does a side strut do

Answer 8

• resists lateral or side way movements

Question 9

What does a drag strut brace do

Answer 9

• used on NLG
• Stabilises longitudinal force

Question 10

Explain the shortening link

Answer 10

• landing gear bay is limited, so it is necessary to shorten the gear during retraction
• mechanism to shorten gear during retraction

Question 11

What does the drag strut do

Answer 11

-stabilises leg against longitudinal movement

Question 12

What are multiple wheels on a main gear called

Answer 12

Bogie

Question 13

What can be fitted to prevent retraction on ground

Answer 13

Ground lock pin

Question 14

Explain the Nose landing gear

Answer 14

• steerable
• does not have brakes
• lighter (as it carries less load)
• not designed to support initial landing load
• retracts forward

Question 15

What is a centring cam

Answer 15

Used for aligning wheels

Question 16

When an aircraft takes off what happens to the inner cylinder

Answer 16

• Inner cylinder drops under its own weight

Question 17

When an aircraft lands, what happens to the inner cylinder

Answer 17

• It is compressed meaning it is shorter in length

Question 18

What is the torque link damper also known as

Answer 18

Shimmy damper

Question 19

How is the shock of a landing absorbed

Answer 19

• energy transferred through the airframe
• by converting energy into heat energy

Question 20

Explain a oleo-pneumatic

Answer 20

Fluid spring with gas or oil (or mixture)
- compressed nitrogen and oil used

Question 21

How are main gear struts serviced

Answer 21

• nitrogen gas + with specific hydraulic fluid

Question 22

What is dimension X/H

Answer 22

The shock struts extension of the inner cylinder

Question 23

Why does the lever of the landing gear have detent positions

Answer 23

• prevent vibration
• accidental selections

Question 24

Why is it crucial to sequence the landing gear correctly

Answer 24

• prevent gear from becoming jammed

Question 25

In the event of hydraulic failure or main system failure, how is the landing gear extended

Answer 25

- system withdraws up-locks - mechanical and electrical linkages - gears free fall and lock under gravity and airflow

Question 26

How is a landing gear system indicated in the cockpit

Answer 26

- Indicator lights - ECAM (electronic centralised aircraft monitor)

Question 27

Colour of each gear indicator meaning Green - Red - No light -

Answer 27

DOWN AND LOCKED UNLOCKED OR TRAVELLING UP AND LOCKED

Question 28

Explain micro switches

Answer 28

- open and close electrical circuit - makes signal via surface contact

Question 29

Why would you use a proximity switch over a micro switch

Answer 29

- In high risk corrosion areas due to dirt and moisture

Question 30

What are the 2 different types of proximity switches used on aircraft

Answer 30

- Reed switch - electronic switch

Question 31

Explain how a reed switch is used

Answer 31

- consists of 2 spring loaded contacts - contacts embedded in glass tube which contains gas to protect against corrosion - contacts closed by magnetic flux

Question 32

Explain the electronic proximity switch

Answer 32

- sensing coil that is done by a electronic unit - target made from non-magnetic ferrous material - electronic unit detects change in coil impedance and switches

Question 33

What are aircraft wheels typically produced from

Answer 33

- Aluminium alloy - Magnesium alloy

Question 34

Do modern aircraft have tube or tubeless tyres

Answer 34

- tubeless

Question 35

What bearings are used for aircraft wheels

Answer 35

- tapered roller bearings

Question 36

Are the brakes fitted to the inboard or outboard do the wheel?

Answer 36

Inboard

Question 37

What are the brake disks driven by

Answer 37

Steel drive keys

Question 38

What does a heat shield do

Answer 38

Prevents the brake heat from damaging the wheels

Question 39

What are thermal relief plugs

Answer 39

Automatically release tyre pressure when the temp of wheel exceeds a certain level

Question 40

What is the relationship between kinetic energy and heat when using the brakes

Answer 40

Kinetic energy is converted to heat energy

Question 41

What extinguisher is used to take out brake fires

Answer 41

Dry powder extinguisher

Question 42

Explain multiple disc brakes

Answer 42

- increased friction surface which maximises braking forces and heat to disperse

Question 43

How lighter is carbon brakes than steel brakes

Answer 43

40% lighter

Question 44

Carbon heat packs withstand temperatures —-% higher than steel component brakes

Answer 44

50

Question 45

How much longer do carbon heat packs last over steel brakes

Answer 45

20% - 50%

Question 46

What is the disadvantage of carbon heat packs over steel heat packs

Answer 46

Expensive

Question 47

Piston clearance is the distance between?

Answer 47

Piston and spring sleeve

Question 48

Before checking the wear of the the brakes what must be done

Answer 48

- parking brakes set - brake must be cold

Question 49

What gives you a visual indicator of the overall wear of the heat pack

Answer 49

- wear indicator pin

Question 50

How does the parking brake system work

Answer 50

Permanent pressurisation of brake hydraulic circuit

Question 51

Anti skid