Have you ever wondered about the comparison between ordinary car tires and aircraft tires? Aside from being both tires, this one got wheels . Hence, they are not built the same. Aircraft tires are very complex as it is. They’re like tires pumped up with steroids.
What makes them unique?
Ordinary car tires and semi-truck tires are not supposed to explode but in some cases, they do. Those tires are not reinforced to withstand the same heavy weight and high speed operations. On the other hand, airplane tires are needed to be reinforced. They are inflated twice more than truck tires and six times more than car tires.
Usually, passenger aircrafts are typically inflated in 200-210 Psi (pound per square-inch) depending on what the aircraft manufacturer requires. In the case of F-16 fighter jet, the tires on that jet would be at 320 Psi. The higher the pressure is, the firmer the tires get. It only means that there is more strength intended to support the whole aircraft. (Note: Main landing gears has higher wheel pressure than the nose wheels).
What makes the landing gear strong?
Manufacturers have different ways of developing their landing wheels but they are guided with the same principles on how to make aircraft wheels tougher.
According to Goodyear, landing tires are made with different combinations of proprietary synthetic rubber compounds. They are paired with reinforcements using aluminum steel together with nylon and aramid fabrics to make them strong.
Landing tires are not inflated with regular air but are filled with nitrogen. Nitrogen is an inert gas that is not susceptible to change the air temperature and pressure. Also, nitrogen has no water vapor present in it, which prevents the formation of ice crystals on the wheels.
How many landings & takeoffs can wheels perform before they are replaced?
The answer is, it depends on the aircraft tire model. Usually, they need to be replaced after approximately 150-200 cycles. However, it can be changed since there are factors to be considered such as weight of the aircraft, landing speed and runway surface condition. Sometimes, the smoothness of the pilot landing the aircraft should also be on the list to consider as well.
Tires must be inspected by the Pilot and mechanics for flat spots and damages before and after the flight to check the security of the wheels. In rare occasions of a tire blow out, wheels can also maintain their basic shape for safe ground handling but it sometimes depends on the damage.
Reusing tires
Aircraft tires can be rethreaded up to seven times before completely replaced depending on the servicing manual. Sometimes, manufacturers recycle the wheels to make a new set.
Melting and Deflating
There is a fusible fuse located inside the hub that will automatically melt if the temperature gets too high. When the wheels in the aircraft get hot, it will catch fire due to hot brakes from the rejected take-off, emergency landing or the leaking hydraulic line. The tires nearby can be prone to over pressurization and blow outs which can be dangerous especially when the firemen try to control the fire. Then, the fusible plug will now do its part.
After melting, the tire will deflate at controlled rate to prevent explosions. Keep in mind that the fusible plug only works for fire and heat conditions. If the reason is not from fire or high heat, blowouts may still occur.
