What material is typically used in thermal fuse plugs installed in aircraft wheel rims?

Thermal fuse plugs in aircraft wheel rims are designed to enhance safety by preventing excessive heat from leading to tire blowouts during high-speed operations or prolonged braking. The correct answer, meltable material, refers to a specific type of material that is engineered to have a predetermined melting point.

When the temperature within the wheel rim rises due to friction or heat buildup, the meltable material will melt and this action will allow for pressure to release, thereby preventing further escalation of heat and potential catastrophic failure of the tire. This controlled failure mechanism is crucial, as it helps maintain the integrity of the wheel assembly and provides a buffer against overheating.

Other materials, such as rubber, plastic, and metal alloys, do not provide the same thermal management capabilities as meltable materials. While rubber and plastic can withstand some degree of heat, they do not have the designed thermal response necessary to ensure the safety features intended in thermal fuse plugs. Similarly, while metal alloys have various applications in aircraft and can withstand high temperatures, they do not serve the same purpose in softening and releasing pressure in the event of overheating, which is the primary function of a thermal fuse plug. Therefore, meltable material is the appropriate choice for this safety feature in aircraft wheel rims.