Which tool is most effective for locating an internal fuel leak in an aircraft fuel system?

The most effective tool for locating an internal fuel leak in an aircraft fuel system is the fuel system schematic. A fuel system schematic provides a detailed visual representation of the fuel system's components and their interconnections. This schematic allows a technician to understand the flow paths and potential points of failure within the system.

When an internal leak occurs, it may not be immediately visible from a standard visual inspection. However, using the schematic, a technician can systematically trace the fuel flow and identify sections of the system where leaks are likely to occur, such as at joints, connections, or through damaged lines. This targeted approach increases the efficiency of troubleshooting and helps confirm whether there is an internal leak.

The other tools, while useful in various contexts, do not provide the same level of insight into the fuel system's architecture. Visual inspection tools are more suited for surface-level examinations, fuel flow meters measure the flow rate but may not indicate where a leak is located, and pressure gauges can help identify pressure drop but do not specifically pinpoint the location of an internal leak. Thus, the schematic stands out as the most comprehensive tool for diagnosing internal leaks effectively.