11.13 LANDING GEAR Flashcards
What are the 3 main landing gear (MLG) arrangements
- tail wheel
- tricycle-type
- Tandem
Where is the aircraft’s CG positioned in a tricycle configuration
- ahead of main wheels
Which configuration is uncommon
- Tabdem configuration
When would you use fixed and retractable landing gear
Low speed aircraft - fixed
High speed aircraft - retractable
What is the function of the MLG in terms of load
- transfers operational loads to the aircraft structure
Explain the trunnion link
- connect top of leg to wing structure
- allows leg to rotate into and out of landing gear bay
The shock strut has 2 telescopic cylinders known as
- outer and inner cylinder
What does a side strut do
- resists lateral or side way movements
What does a drag strut brace do
- used on NLG
- Stabilises longitudinal force
Explain the shortening link
- landing gear bay is limited, so it is necessary to shorten the gear during retraction
- mechanism to shorten gear during retraction
What does the drag strut do
-stabilises leg against longitudinal movement
What are multiple wheels on a main gear called
Bogie
What can be fitted to prevent retraction on ground
Ground lock pin
Explain the Nose landing gear
- steerable
- does not have brakes
- lighter (as it carries less load)
- not designed to support initial landing load
- retracts forward
What is a centring cam
Used for aligning wheels
When an aircraft takes off what happens to the inner cylinder
- Inner cylinder drops under its own weight
When an aircraft lands, what happens to the inner cylinder
- It is compressed meaning it is shorter in length
What is the torque link damper also known as
Shimmy damper
How is the shock of a landing absorbed
- energy transferred through the airframe
- by converting energy into heat energy
Explain a oleo-pneumatic
Fluid spring with gas or oil (or mixture)
- compressed nitrogen and oil used
How are main gear struts serviced
- nitrogen gas + with specific hydraulic fluid
What is dimension X/H
The shock struts extension of the inner cylinder
Why does the lever of the landing gear have detent positions
- prevent vibration
- accidental selections
Why is it crucial to sequence the landing gear correctly
- prevent gear from becoming jammed
In the event of hydraulic failure or main system failure, how is the landing gear extended
- system withdraws up-locks
- mechanical and electrical linkages
- gears free fall and lock under gravity and airflow
How is a landing gear system indicated in the cockpit
- Indicator lights
- ECAM (electronic centralised aircraft monitor)
Colour of each gear indicator meaning
Green -
Red -
No light -
DOWN AND LOCKED
UNLOCKED OR TRAVELLING
UP AND LOCKED
Explain micro switches
- open and close electrical circuit
- makes signal via surface contact
Why would you use a proximity switch over a micro switch
- In high risk corrosion areas due to dirt and moisture
What are the 2 different types of proximity switches used on aircraft
- Reed switch
- electronic switch
Explain how a reed switch is used
- consists of 2 spring loaded contacts
- contacts embedded in glass tube which contains gas to protect against corrosion
- contacts closed by magnetic flux
Explain the electronic proximity switch
- 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
What are aircraft wheels typically produced from
- Aluminium alloy
- Magnesium alloy
Do modern aircraft have tube or tubeless tyres
- tubeless
What bearings are used for aircraft wheels
- tapered roller bearings
Are the brakes fitted to the inboard or outboard do the wheel?
Inboard
What are the brake disks driven by
Steel drive keys
What does a heat shield do
Prevents the brake heat from damaging the wheels
What are thermal relief plugs
Automatically release tyre pressure when the temp of wheel exceeds a certain level
What is the relationship between kinetic energy and heat when using the brakes
Kinetic energy is converted to heat energy
What extinguisher is used to take out brake fires
Dry powder extinguisher
Explain multiple disc brakes
- increased friction surface which maximises braking forces and heat to disperse
How lighter is carbon brakes than steel brakes
40% lighter
Carbon heat packs withstand temperatures —-% higher than steel component brakes
50
How much longer do carbon heat packs last over steel brakes
20% - 50%
What is the disadvantage of carbon heat packs over steel heat packs
Expensive
Piston clearance is the distance between?
Piston and spring sleeve
Before checking the wear of the the brakes what must be done
- parking brakes set
- brake must be cold
What gives you a visual indicator of the overall wear of the heat pack
- wear indicator pin
How does the parking brake system work
Permanent pressurisation of brake hydraulic circuit
Anti skid
