Wheels - Wheels & Tyres - Airframes & Aircraft Systems #19

Summary

This lesson delves into the intricacies of aircraft wheel design, focusing on the composition and materials of wheels and tires. It highlights the role of pneumatic tires in cushioning landing shocks and the necessity for specialized tire replacement due to their size and stiffness. The two common wheel types—loose or detachable flange and divided—are compared, with emphasis on their ease of tire change without aircraft disassembly. Additional safety features like fusible plugs, designed to prevent tire blowouts by deflating tires in controlled ways during overheating, are also discussed.

Takeaways

• ✈️ Aircraft wheels and tires support the aircraft on the ground and facilitate mobility during takeoff, landing, and taxiing.
• 🛠 Pneumatic tires help cushion the aircraft from shocks due to uneven ground surfaces and absorb some of the impact during landing.
• 🔧 Main wheels and sometimes nose wheels house brake units, which control the aircraft's movement on the ground and aid in deceleration during landing.
• 🔩 There are two common types of aircraft wheels: loose or detachable flange type and divided wheel, each with different securing methods for the removable flange.
• 🔄 Loose flange wheels are retained by a locking device and tire pressure, while detachable flange wheels use nuts and bolts for securing the flange.
• 🔧 The divided wheel is the most common type, consisting of two half wheels joined by bolts, designed for easy tire change without removing the wheel from the aircraft.
• 💡 Wheels often feature an outboard flange to prevent tire creep during heavy braking, which can damage the tire and cause blowouts.
• 🛠 Aircraft wheels are made of aluminum or magnesium alloy, with aluminum being more common due to its resistance to corrosion and lower flammability.
• 🔧 Wheels for tubeless tires are ground to a finer finish and impregnated with bakelite to create an airtight seal and prevent air leakage.
• 🔥 Fusible plugs are incorporated into some wheels to prevent tire blowouts caused by excessive heat, allowing controlled tire deflation if overheating occurs.

Q & A

What is the primary function of aircraft wheels and tires?

The primary function of aircraft wheels and tires is to support the aircraft when on the ground, provide mobility for takeoff, landing, and taxiing, and cushion the aircraft from shocks due to irregularities in the ground surface.

How do the pneumatic tires of an aircraft assist during landing?

Pneumatic tires help to absorb shocks during landing and take some of the shock on landing, which is crucial for the aircraft's safe touchdown.

What is the role of brake units in aircraft wheels?

Brake units housed in the main wheels control the movement of the aircraft on the ground and provide a means of deceleration during landing.

What are the two common types of aircraft wheels mentioned in the script?

The two common types of aircraft wheels mentioned are the loose or detachable flange type and the divided wheel.

How does the loose flange type of wheel secure its removable flange?

In the loose flange type, the removable flange is retained by a locking device on the wheel rim and held in place by the tire pressure.

What is the advantage of using loose and detachable flange type of wheels?

The advantage is that the tire can be changed without removing the wheel from the aircraft, which simplifies maintenance and replacement processes.

How are the two halves of a divided wheel joined together?

The two halves of a divided wheel are matched up and joined together by bolts that pass through both halves, with stiff nuts or locking plates securing the bolts.

Why is it important to maintain correct tire gas pressure in aircraft wheels?

Correct tire gas pressure helps prevent excessive tire creep around the wheel, which can lead to the tearing out of the inflation valve and potential tire burst.

What materials are commonly used to manufacture aircraft wheels?

Aircraft wheels are commonly made of either aluminum or magnesium alloy. Aluminum alloys are normally used unless low weight is essential due to magnesium's susceptibility to corrosion and flammability.

What is the purpose of fusible plugs in aircraft wheels?

Fusible plugs are fitted in some wheels with tubeless tires to prevent sudden tire blowouts due to excessive heat. They release the gas in a controlled manner if the temperature reaches a critical level.

How do fusible plugs protect tires from explosion due to overheating?

Fusible plugs are screwed into holes in the wheel rim and sealed by a piston held in place by a fusible alloy. When excessive heat melts the alloy, the piston escapes, allowing the tire to deflate in a controlled manner, thus preventing a sudden blowout.