Aircraft Landing Gear Systems

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Questions and Answers

What design considerations allow aircraft wheels to effectively perform their function?

Lightweight, strong construction, typically using aluminum alloy. (correct)
Manufactured exclusively from steel for maximum durability.
Complex, multi-piece assembly to facilitate easy repair.
Heavyweight construction to enhance ground stability.

Which of the following is NOT a primary function of aircraft tires?

Generating lift during takeoff to assist the wings. (correct)
Absorbing shock from landing and taxiing to protect the aircraft structure.
Providing gripping contact with the runway surface for effective braking and steering.
Supporting the aircraft’s weight during taxi, takeoff, and landing.

What is the primary function of the trunnion in a landing gear assembly?

To house the retraction actuator.
To directly absorb the impact forces during landing.
To provide a mounting point on the airframe that allows the landing gear to pivot during retraction and extension. (correct)
To facilitate steering of the aircraft during taxiing.

What is the role of the drag link (or drag strut) in a landing gear system?

To stabilize the shock strut longitudinally. (A) Signup and view all the answers

What is the purpose of the side strut (or side brace link) in a landing gear system?

To stabilize the landing gear laterally. (C) Signup and view all the answers

Which of the following describes the function of an overcenter link in a landing gear system?

It prevents pivoting at the joint except during retraction, locking the gear in the down position to prevent collapse. (B) Signup and view all the answers

How do downlock and uplock mechanisms function in a landing gear system?

The downlock secures the landing gear in the down position, while the uplock secures it in the up position. (C) Signup and view all the answers

What is the primary function of the axle in the landing gear assembly?

To support and provide a mounting point for the main wheels. (A) Signup and view all the answers

In a typical pneumatic/hydraulic shock strut, what is the primary purpose of the nitrogen gas?

To absorb and dissipate shock loads through compression. (A) Signup and view all the answers

During the compression stroke of a shock strut, what immediate effect does the upward movement of the metering pin through the orifice have?

It reduces the volume of the gas, thereby increasing its pressure. (B) Signup and view all the answers

What is the fundamental difference between shock-absorbing and non-shock-absorbing landing gear systems in terms of energy management?

Shock-absorbing systems convert impact energy into heat and alter its transfer rate, while non-shock-absorbing systems primarily transfer the impact force to the airframe for dissipation. (A) Signup and view all the answers

What is the significance of the orifice in a pneumatic/hydraulic shock strut?

It provides a controlled passage for hydraulic fluid between the cylinders, affecting the rate of compression and energy absorption. (D) Signup and view all the answers

Why do aircraft with non-shock-absorbing landing gear use flexible materials like spring steel or composites?

To enable the gear to flex and transfer impact forces to the airframe at a less harmful rate. (D) Signup and view all the answers

During landing, what causes the vertical speed of the aircraft to decrease when a shock strut is compressed?

The hydraulic fluid being forced through the metered opening, increasing pressure and temperature within the cylinder. (B) Signup and view all the answers

During the recoil phase of a shock strut's operation, what primary action characterizes its function?

The strut extends until the gas pressure balances the aircraft’s weight, providing shock absorption during taxiing. (B) Signup and view all the answers

What is the primary trade-off considered when deciding between fixed and retractable landing gear systems for an aircraft?

Reduced drag from retractable gear versus increased weight and complexity. (A) Signup and view all the answers

What determines the point at which the energy stored in the gas pressure of a shock strut is sufficient to recoil the aircraft upwards?

The increase in gas pressure sufficient to counteract and overcome the aircraft's downward vertical motion. (B) Signup and view all the answers

In a typical aircraft landing gear system, what initial action occurs when the landing gear handle is set to the 'UP' position?

The selector valve directs hydraulic pressure to unlock wheel well doors and landing gears. (C) Signup and view all the answers

Consider an aircraft equipped with hydraulic landing gear encountering an unusually hard landing. What adjustment within the shock strut system would most effectively mitigate the impact force in subsequent landings, assuming the aircraft's weight remains constant?

Increase the orifice size to facilitate a faster transfer of hydraulic fluid between cylinders. (B) Signup and view all the answers

What is the function of the uplock mechanism in a landing gear system?

To mechanically secure the landing gear in the retracted ('UP') position. (D) Signup and view all the answers

What happens when the landing gear handle is set to the 'OFF' (neutral) position in the context of hydraulic pressure?

All components of the landing gear operation system are connected to the hydraulic system's return line. (A) Signup and view all the answers

In a typical aircraft landing gear system, hydraulic pressure is directly responsible for which function?

Unlocking the uplock mechanism to release the landing gear from its retracted position. (C) Signup and view all the answers

What is the immediate consequence of moving the landing gear handle to the 'DOWN' position?

Hydraulic pressure is released via the selector valve to extend the gear. (C) Signup and view all the answers

Considering the retraction of an aircraft's main landing gear, what is primarily being overcome when the downlock actuator pulls the overcenter links?

The bungee spring tension maintaining the 'overcenter' positon. (A) Signup and view all the answers

When the landing gear is unlocked, what is the primary factor that initiates its movement towards the 'down and locked' position?

Tension from the bungee springs and the gear's own mass. (A) Signup and view all the answers

An aircraft is designed to minimize drag during high-speed flight. Which of the following statements accurately justifies the selection of retractable landing gear for this aircraft?

The reduction in drag achieved by retracting the gear outweighs the added weight, enhancing overall aerodynamic efficiency. (A) Signup and view all the answers

Aircraft main landing gear retract actuator has a maximum force of 53,000N and a stroke of 700mm. If the retraction time is 10 seconds, and given the cap end diameter is 500mm and piston rod diameter is 300mm, which formula accurately calculates the volume required to retract three actuators (two main and one nose)?

$3 imes (\pi/4) imes (0.5^2 - 0.3^2) imes 0.7$ (A) Signup and view all the answers

Consider an aircraft where, upon selecting 'UP' on the landing gear handle, the wheel well doors fail to open. What is the most likely cause of this malfunction, assuming the hydraulic system is functional?

The unlatch and door actuator is malfunctioning, preventing the wheel well doors from opening. (A) Signup and view all the answers

Using the parameters of the retraction of an aircraft's three landing gear actuators (two main and one nose), the calculated flow rate is $0.0263 m^3/s$. Given a system pressure of 207 bar and an overall pump efficiency of 85%, which of the following formulas correctly calculates the power required in kilowatts?

$(207 imes 10^5 imes 0.0263) / 0.85$ (C) Signup and view all the answers

During ground maintenance of an aircraft, landing gear lock pins are inserted into the overcenter mechanism. What hazardous condition is MOST directly prevented by this safety measure?

Unintentional retraction of the landing gear due to hydraulic system pressure. (C) Signup and view all the answers

In the context of an aircraft landing gear system, what is the MOST critical function of the 'overcenter links' within the downlock mechanism?

To ensure the side brace cannot pivot when the landing gear is in the 'DOWN' position. (D) Signup and view all the answers

Why is understanding the hydraulic power requirements crucial to designing and maintaining an aircraft landing gear system?

It ensures the landing gear operates reliably and efficiently under various conditions. (D) Signup and view all the answers

What is the primary purpose of the hydraulic fluid that flows away from the retraction actuator in a landing gear system?

To slow down the retraction process and reduce 'down' shock. (A) Signup and view all the answers

During aircraft taxiing, which methods are primarily used to steer the aircraft?

Nose wheel steering system and/or differential braking. (A) Signup and view all the answers

What is the function of torque links or torque arms in a landing gear shock strut?

To keep the wheels aligned and prevent rotation of the lower cylinder. (A) Signup and view all the answers

What is the purpose of the locating cam assembly in a nose gear shock strut?

To keep the gear aligned ensuring the nose wheel enters the wheel well during retraction. (D) Signup and view all the answers

What is the role of the metering valve in the nose landing gear steering system?

To control the flow of hydraulic fluid to and from the steering cylinders. (C) Signup and view all the answers

In the nose landing gear steering system, what happens to the fluid forced out of steering cylinder B during a right turn?

It is directed through the metering valve and into a compensator before returning to the hydraulic system. (C) Signup and view all the answers

How does the extension of the piston in steering cylinder A contribute to turning the nose wheel to the right?

It turns the steering spindle connected to the shock strut, causing the nose wheel to turn. (A) Signup and view all the answers

Why is it important for the nose gear to be aligned with the longitudinal axis of the aircraft prior to landing?

To ensure that the aircraft can maintain a straight and stable course upon touchdown. (C) Signup and view all the answers

What is the primary function of the main landing gear in an aircraft?

To absorb the impact forces during landing and ground operations. (D) Signup and view all the answers

In a tricycle landing gear configuration, how does the position of the center of gravity contribute to preventing ground-looping?

The center of gravity being forward of the main gear promotes forward motion and resists pivoting. (A) Signup and view all the answers

What is the primary advantage of using a tricycle landing gear configuration over a tailwheel configuration in modern aircraft?

Improved visibility from the flight deck during landing and taxiing. (C) Signup and view all the answers

Which factor most significantly determines the number of landing gears, wheels, and brakes required on an aircraft?

The maximum takeoff weight and load capacity of the aircraft. (C) Signup and view all the answers

Why are brakes installed on the main landing gear of an aircraft?

To reduce the aircraft's speed during landing and taxiing. (D) Signup and view all the answers

What is the primary purpose of the nose landing gear in an aircraft?

To support the aircraft's weight and enable ground maneuvering. (A) Signup and view all the answers

Which characteristic is most associated with aircraft using a tailwheel landing gear configuration?

Suitability for operation on rough or unpaved surfaces. (D) Signup and view all the answers

How does a tricycle landing gear configuration typically improve safety during braking compared to a tailwheel configuration?

By allowing for more forceful braking without the risk of nosing over. (D) Signup and view all the answers

Flashcards

Aircraft Wheels

Supports the aircraft's weight during taxi, takeoff, and landing.

Aircraft Tyres

Supports aircraft weight, absorbs landing shock, grips the runway, and discharges static electricity.

Trunnion

Part of the landing gear attached to the airframe, allowing gear to pivot during retraction/extension.