Where are fusible plugs installed on the wheel?

• A. Outboard half of the main wheels
• B. Inboard half of the main wheels
• C. On the brake rotor
• D. Around the valve stem

Answer: (B)

Fusible plugs are heat-activated safety devices built into aircraft wheel rims to relieve pressure if the brakes overheat or the tire overheats, helping prevent a wheel/ tire failure. They’re placed in the inboard half of the main wheels so that, if the plug melts, the released air and heat vent into the wheel cavity toward the hub rather than near the brake surfaces or outside where damage could occur. This location also aligns with the wheel’s internal airflow and maintenance access. Placing them in the brake area (outboard half) or around the valve stem would not provide the controlled relief these devices are designed for, so the inboard half is the correct placement.