Safety Features - Landing Gear - Airframes & Aircraft Systems #18

Summary

This lesson focuses on the critical safety features of aircraft landing gear systems, ensuring correct operation and preventing damage. It covers the mechanisms for nosewheel alignment, gear retraction safety devices, and gear extension warnings. The script also discusses ground locks, emergency lowering systems, and the pilot's responsibility for aircraft configuration. The lesson highlights the importance of these systems in maintaining flight safety.

Takeaways

• 🔐 Safety features in aircraft landing gear systems are crucial for preventing damage and ensuring correct operation.
• 🎯 The nosewheel must be aligned in the fore and aft direction before retraction, which is achieved through hydraulic centering or self-centering cams.
• 🚫 A mechanical lock with an electrically operated solenoid prevents the landing gear from being retracted unsafely.
• ⚙️ On smaller aircraft, the solenoid is controlled by switches on the main gear shock absorber struts, which close as the struts extend.
• 🔄 Larger aircraft require additional criteria, such as correct gear truck angle and body gear steering alignment, before the gear can be safely retracted.
• 🔄 An override mechanism is provided for maintenance and in case of solenoid failure, but should be used with caution to avoid damage.
• 🔒 Landing gear ground locks or locking pins prevent the gear from retracting when the aircraft is on the ground, ensuring safety.
• 🚨 An aural warning system alerts pilots if the landing gear is not locked down, with an isolation switch for specific flight exercises.
• 🛠️ In the event of a hydraulic system failure, there are provisions to manually lower and lock the landing gear in the down position.
• ✈️ The pilot remains ultimately responsible for ensuring the aircraft's correct configuration for each phase of flight, despite the presence of safety systems.

Q & A

Why is the correct operation of the landing gear considered of utmost importance?

The correct operation of the landing gear is of utmost importance because it ensures the safety of the aircraft and its occupants during takeoff and landing.

What are the safety features included in the retraction and extension systems of the landing gear?

The safety features in the retraction and extension systems include mechanisms to stop the gear from retracting when it's not safe, warnings to the crew if they attempt to land with the gear not extended, and methods to ensure the nosewheel is aligned before retraction.

How does the hydraulic nose wheel centering method work on aircraft with powered steering?

On aircraft with powered steering, the hydraulic nose wheel centering method automatically aligns the nosewheel in the fore and aft direction prior to retraction.

What is the purpose of the mechanical lock in the landing gear selector lever?

The mechanical lock in the landing gear selector lever prevents the gear from being retracted when it's not safe to do so by retaining the selector in the down position until released by an electrically operated solenoid.

How do the switches on the main gear shock absorber struts control the electrical power to the solenoid in smaller aircraft?

In smaller aircraft, the switches on the main gear shock absorber struts control the electrical power to the solenoid by being open when the struts are compressed and closing as the struts extend after takeoff, thus releasing the selector lever lock.

What additional criteria must be met on larger aircraft before it is safe to raise the landing gear?

On larger aircraft, additional criteria such as the main gear trucks being tilted to the correct angle and the gear being aligned for aft-only movement must be met before the lever lock is released to raise the landing gear.

What is the purpose of the landing gear ground locks or locking pins?

Landing gear ground locks or locking pins are safety features designed to prevent the inadvertent retraction of the gear when the aircraft is on the ground, ensuring that the gear cannot move while they are in position.

How does the aural warning system work in the landing gear system?

The aural warning system in the landing gear provides an audible alert if the gear is not locked down, typically triggered by certain combinations of flap and throttle positions, and can be silenced using an isolation switch except in critical conditions.

What is the Enhanced Ground Proximity Warning System (EGPWS) and how does it relate to the landing gear?

The Enhanced Ground Proximity Warning System (EGPWS) provides a 'too low gear' warning if the aircraft passes a specified radio altitude with the gear not locked down, supplementing the safety measures for landing gear operation.

How can the landing gear be lowered in the event of a hydraulic system failure?

In the event of a hydraulic system failure, the landing gear can be lowered using alternative methods such as electrically releasing the up locks, using a hand pump, or activating an emergency pressure system that may utilize hydraulic accumulators or pneumatic storage cylinders.

What is the responsibility of the pilot regarding the landing gear configuration?

The pilot is ultimately responsible for ensuring that the aircraft is in the correct configuration for each phase of flight, which includes verifying the landing gear is properly extended or retracted as required.