AMT Aircraft Landing Gear Systems 1 — Questions and Answers
Question 1: What is the primary purpose of a shimmy damper on aircraft landing gear?
- To absorb vertical shock loads during landing
- To prevent oscillation of the nose wheel assembly (Correct answer)
- To control the rate of gear retraction
- To provide steering input to the nose wheel
Correct answer: To prevent oscillation of the nose wheel assembly
A shimmy damper dampens nose wheel oscillations (shimmy) that can occur during ground operations by providing hydraulic resistance to rapid lateral movement.
Question 2: In an oleo-pneumatic shock strut, landing shock is cushioned primarily by:
- A coil spring compressed by the piston
- Nitrogen gas compression and hydraulic fluid metering through orifices (Correct answer)
- Rubber biscuits compressed between metal discs
- A leaf spring assembly attached to the axle
Correct answer: Nitrogen gas compression and hydraulic fluid metering through orifices
Oleo-pneumatic struts use compressed nitrogen gas and hydraulic fluid forced through metering orifices to absorb and dissipate landing shock energy during compression.
Question 3: Torque links (scissors links) on an oleo shock strut serve to:
- Allow free rotation of the piston within the outer cylinder
- Prevent rotation of the piston while allowing axial (vertical) movement (Correct answer)
- Provide steering input to the nose wheel during ground operations
- Lock the landing gear in the fully extended position
Correct answer: Prevent rotation of the piston while allowing axial (vertical) movement
Torque links connect the inner and outer cylinders of an oleo strut, preventing rotational movement of the piston while allowing it to move axially for shock absorption.
Question 4: What type of landing gear arrangement is most commonly used on modern large transport aircraft?
- Fixed tricycle gear
- Retractable tricycle gear (Correct answer)
- Conventional (tailwheel) gear
- Bicycle gear with outriggers
Correct answer: Retractable tricycle gear
Retractable tricycle gear is standard on modern transport aircraft because it reduces aerodynamic drag in flight and provides stable ground handling with good pilot forward visibility.
Question 5: The purpose of a downlock in a retractable landing gear system is to:
- Prevent the gear from retracting accidentally while on the ground
- Hold the landing gear in the fully extended position during flight (Correct answer)
- Lock the gear doors closed after the gear extends
- Prevent the wheels from spinning during gear retraction
Correct answer: Hold the landing gear in the fully extended position during flight
A downlock mechanically secures the landing gear in the fully extended position during flight, preventing inadvertent retraction or collapse under aerodynamic or asymmetric loads.
Question 6: Proper aircraft wheel bearing preload is important because:
- It prevents the bearing races from separating under radial loads only
- Excessive preload always extends bearing service life
- Proper preload prevents both excessive play and heat buildup from overtightening (Correct answer)
- Preload allows bearings to operate without lubrication
Correct answer: Proper preload prevents both excessive play and heat buildup from overtightening
Correct bearing preload eliminates excessive looseness (which causes wobble and impact loading) while avoiding overtightening (which causes friction heat buildup and premature bearing failure).
Question 7: An anti-skid brake system prevents wheel lockup by:
- Increasing hydraulic pressure to the brakes when a skid is detected
- Automatically releasing and reapplying brake pressure to allow the wheel to spin up (Correct answer)
- Mechanically limiting brake pedal travel at a fixed position
- Reducing engine thrust when wheel skidding is detected by sensors
Correct answer: Automatically releasing and reapplying brake pressure to allow the wheel to spin up
Anti-skid systems monitor wheel deceleration rates to detect impending lockup, then momentarily reduce brake hydraulic pressure to allow the wheel to regain traction before reapplying pressure.
AMT Aircraft Landing Gear Systems 1
What is the primary purpose of a shimmy damper on aircraft landing gear?