What might indicate a fuel leak during pre-flight inspections?

A puddle beneath the aircraft is a clear and visible indication of a fuel leak during pre-flight inspections. This accumulation of fuel can occur when there is a failure in the fuel lines, fittings, or any part of the fuel system that prevents the fuel from being contained within the tank or delivery system. Noticing a puddle not only alerts the pilot to a potential safety hazard but also necessitates an immediate investigation into leaks before the aircraft can be deemed safe for flight.

In contrast, increased fuel gauge readings generally suggest that the fuel tank is full or that fuel may have been added, which is not an indication of a leak. Similarly, normal engine performance would indicate that the fuel system is functioning correctly, and there would be no leak present, while overheating engine components could be a sign of other issues related to engine operation but does not directly correlate to a fuel leak. Therefore, while those factors may influence pre-flight inspections, they do not serve as direct indicators of fuel leakage.