Landing Gear Introduction Flashcards

1
Q

What is the primary function of the aircraft landing gear?

A
  1. Maneuvering during ground operations

2. Absorb the loads associated with landing and take-off.

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2
Q

What are the different structures that can be used as landing gear?

A
  1. Wheels and tyres
  2. Skis
  3. Skids
  4. Floats
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3
Q

What are three types of landing gear installed on fixed wing aircraft?

A
  1. Fixed
  2. Retractable
  3. Floats/Floating Hull
  4. Skis/Skids
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4
Q

What are three different types of undercarriage configuration?

A
  1. Conventional
  2. Tricycle
  3. Tendem
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5
Q

What are some major components of a landing gear system and what are their functions?

A

1) Shock absorbers - Absorb sudden impact of loads on aircraft landing, mechanical/hydraulic construction designed to convert kinetic energy created into heat via fluid transfer within the unit.
2) Air/Oil Oleo Struts - A more advanced form of shock absorber which accommodates greater loads, contains separate air (nitrogen) and hydraulic fluid compartments
3) Uplocks/Downlocks - mechanicals locks that keep landing gear in their intended position
4) Undercarriage doors
5) Cockpit Indications
6) Hydraulic Accumulator

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6
Q

What are four types of aircraft steering configurations?

A

1) Rudder Steering - aerodynamic steering from airflow and rudder.
2) Direct Steering - Pilot induced movement of the nosewheel via electrical, mechanical or hydraulic means - normally operated by rudder pedals
3) Differential braking - Asymmetric braking applicated
4) Tiller Steering - small steering wheel in the cockpit.

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7
Q

What are the two main steering components?

A
  1. Rudder Pedals/brakes

2. Tiller

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8
Q

What are the primary functions of the Weight on Wheels (WOW)/Squat Switch in the aircraft?

A

1) Indicate the position of the associated landing gear strut upon which it is located
2) Report to cockpit indication system (visual/audio)
3) Prevent inadvertent undercarriage retraction while the aircraft is on the ground by enabling electrical isolation of the retraction control circuit.

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9
Q

What are some alternate methods of lowering the landing gear, should the main system fail?

A
  1. Alternate hydraulic supply (redundancy system)
  2. Stored hydraulic supply (accumulator)
  3. Compressed air or nitrogen
  4. Mechanical release
  5. Electrical release
  6. Manual-crank
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10
Q

What are some main braking designs?

A

1) Disk Brakes - hydraulically or pneumatically powered
2) Thrust Reversers
3) Spoilers
4) Drogue/Drag Chute

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11
Q

What is aquaplaning and what are some consequences?

A
  • Traction is lost between the tyre and runway, due to the tyres inability to dissipate the volume of fluid between it and the ground surface.
  • Causes an inability to steer or brake
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12
Q

What is partial dynamic aquaplaning?

A
  • Rotating tyre causes hydrodynamic pressure to slowly lift the tyre on the surface
  • Only a proportion of traction is available.
  • High ground speeds
  • Loss of traction, however, when speed decreases, traction increases.
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13
Q

What is full dynamic aquaplaning?

A
  • The tyre fully lifts from the surface

- Depends on stationary/rotating wheel and the pressure of the tyre.

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14
Q

What is viscous aquaplaning?

A

Oil or accumulated rubber combines with water on a runway to create an impenetrable layer of liquid that the tyres can’t break through.

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15
Q

What is reverted rubber aquaplaning?

A

On a damp runway with no visible water and is similar to a dry skid.

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16
Q

What are some methods to avoid aquaplaning?

A
  • Porous/grooved runways
  • Tyre tread type and depth can also reduce aquaplaning.
  • Piloting techniques which call for a firm touchdown onto wet runways to allow the tyre to penetrate the water and begin the braking action.
17
Q

What is the purpose of anti-ski systems?

A

To mitigate aquaplaning, skidding or excessive braking.

18
Q

What are some advantages of anti-ski systems?

A

1) Increases in control during instances of low traction
2) Reduction of tyre blow-outs due to skidding
3) Pilot input is minimized during sequences of adverse conditions
4) Alternate traction control technology for more complex system

19
Q

What are main materials used in wheel construction?

A
  1. Aluminium

2. Magnesium alloy

20
Q

What are the two major wheel designs?

A
  1. Two Piece

2. Removable flange

21
Q

What are fusible plugs?

A
  • Prevention of failure of tyres cause by excessive heat.

- Small plug of alloy that will melt at a pre-designed temperature allowing the deflation of a tyre in a benign manner.

22
Q

What are some common causes of wheel damage/failure?

A
  1. Over/under inflation of tyres
  2. Corrosion
  3. Excessive brake heat
  4. Heavy landing
23
Q

What are two main tyre classifications?

A
  1. Tube

2. Tubeless

24
Q

What are all tyres marked to indicate?

A
  1. Size
  2. Speed rating
  3. Ply rating
  4. Tubed or tubeless
25
Q

What are tyres inflated to high pressures?

A
  1. To increase rigidity against the sidewall

2. Enable greater resistance to tyre deformation

26
Q

What gas are aircraft tyres filled with? Why?

A
  • Nitrogen
  • Nitrogen has a greater resistance to the expansion/contraction cause by temperature variance
  • Increased fire resistance due to the reduce amount of oxygen available
  • Nitrogen diffuses through rubber at a slower rate than oxygen
  • Increases tyre life due to decreased risk of blowout