What will happen to fusible plugs installed in some aircraft wheels at elevated temperatures?

Fusible plugs serve an important safety function in aircraft wheels, particularly in preventing tire blowouts caused by excessive temperatures. At elevated temperatures, the material of the fusible plug is designed to melt. This melting action allows any built-up pressure within the wheel assembly, which could arise due to tire overheating, to be vented safely.

When the plug melts, it effectively creates an opening, leading to the release of air from the tire, thus preventing a catastrophic failure that could occur from the tire bursting. The melting point is carefully selected to ensure that it activates at temperatures that could result in overheating situations, thereby enhancing safety during operations.

In contrast, other options describe scenarios that are not aligned with the functionality of fusible plugs. For instance, plugs do not freeze at elevated temperatures, will not detach from the wheel since they are designed to remain attached until a specific temperature is reached, and they will not expand and leak in a conventional sense, as this doesn’t relate to the purpose these plugs serve. Instead, they are intended to melt and release pressure to maintain safety.