A wheel “fusible plug”, or “fuse plug” is a safety device installed in the wheels of all airplanes.
A number of holes are drilled in the landing gear wheels; these holes are filled with plugs made of a metal alloy having a low melting point. When the wheels become excessively hot, such as during a high-energy rejected takeoff, the fuse plugs melt and allow the tire pressure to be released. The intent of the fuse plugs is to prevent possible tire explosion that might otherwise occur when wheel temperatures become very high and tire pressures become potentially dangerous.
If you have ever seen the aftermath of a high-energy RTO, you have probably seen that some or all of the tires have deflated. That is due to the action of the wheel fuse plugs, which melted when the wheels were heated excessively by the brakes.
Possible Brake Problems on Short-haul Operations :
Operators conducting “short-haul” operations characterized by short flight times and short ground times would do well to keep the following facts in mind:
–Brake energy is cumulative.
–It’s easy to make brakes hot.
–It’s not easy to make brakes cool.
Imagine an operation having short flight times and short ground times. The first landing won’t cause fuse plug melting, but it will pump some kinetic energy into the brakes. Sitting on the ground, brake cooling is very slow, so short ground times will offer little brake cooling. Short flight times won’t offer much cooling either, so the next landing after pumping some more kinetic energy into the brakes will probably leave them somewhat hotter than the previous landing.
Sooner or later, if this pattern continues, the fuse plugs will probably reach their melting point unless some actions are taken to avoid that possibility.
Author – Zinhom Mohmoud ( Aviation Training Consultant)
