Which tank family provides a magnetic site gauge usable as a mechanical indication of fuel level?

• A. Auxiliary fuel tanks
• B. Main fuel tanks
• C. Wing tanks
• D. Centerline tanks

Answer: (A)

A magnetic site gauge is a simple, mechanical way to read fuel level using a float inside the tank that moves with the fuel. The float carries magnets, and as it rises or falls with the fuel, it moves an external, magnetically coupled indicator to show the level without needing electrical power or complex sensors.

Auxiliary fuel tanks are the ones that benefit from this independent, robust indication. They’re often removable or externally mounted and may not be tied into the aircraft’s main fuel-management instrumentation. Having a magnetic site gauge provides a direct, readable fuel level outside the tank itself, which is reliable during loading, preflight checks, or when electrical systems are unreliable. In contrast, main, wing, and centerline tanks typically rely on the aircraft’s broader fuel management system or different types of sensors, so the magnetic site gauge is not their typical configuration.