What you should know about… aircraft tire damage and blowouts

 

A Boeing 777 uses 14 tires, Airbus' A380 carries 22 and the enormous Antonov An-225 has 32. The key to their remarkable durability is maximizing the air pressure. The high-flying rubber is typically inflated to 200 psi, roughly six times what you put in an automobile tire, and the tires on an F-16 fighter are pumped to 320 psi.

 

In the first moments after a plane touches down, the tires are skidding, not rolling. The non-rotating wheel, moving at about 300 km/h, suddenly touches the concrete. The airplane essentially drags them down the runway until their rotational velocity matches the velocity of the plane. That's why they smoke upon landing and why tires use grooves instead of the block patterns seen on your car's rubber—blocks would simply break off. The stoutest tires are rated for speeds of up to 288 mph.

 

 

Stress for tires?

Tires rapidly go through temperature cycles. In flight they reach -50 °C (-58 °F) and, on touchdown, they rapidly heat up to several hundred °C/°F. Brief exposure to high temperatures is not as damaging to the tires as are prolonged exposures. But external heat sources, for example, brakes, can cause severe damage.

 

Underinflating or overinflating a tire will increase shear forces rapidly shortening the life of an aircraft tire. Common types of damage associated with these forces are shoulder separation and lower sidewall compression break. Treads can come off and casings can blow out. Also, FOD (foreign object debris) that damages tires is a major reason for blowouts.

 

 

Measures to avoid blowouts or the hazard they present

First of all, the tires on airplanes are filled with nitrogen, not air. There have been accidents caused by a tire bursting and causing a fire. Nitrogen reduces the possibility of such a fire. Additionally, it is the high pressure that gives airliner tires their strength. Of course, the tire construction needs to be of tougher stuff than your average car tire but the strength of the rubber compounds is primarily to allow such high pressure inflation rather than to resist impact on landing. The tires are inflated to about 200 psi or about six times the psi of a car tire.

 

 

What happens in the case of a blowout?

To land an Airbus A320 on 21 September 2005 at Los Angeles Airport, the aircraft pilot pulled off a tour de force. During the landing, he kept the aircraft on the four back wheels for as long as possible. Despite this, a locked landing gear began to glow because of the tremendous friction. But the tires did not explode. This is because aircraft tires are equipped with a special venting system that automatically releases the gas in the tires upon reaching a specific temperature. In this way, the designers prevent the tires from exploding and damaging engines or fuel tanks, for example, with flying rubber parts.

 

Besides that, large commercial or cargo aircraft, such as the Airbus A380, often have more than 20 tires, providing enough stability to safely land even if one fails.