How can leaks and defects within the internal portions of the fuel system typically be identified?

Identifying leaks and defects within the internal portions of the fuel system is primarily accomplished through visual inspection for wet spots and stains. This method allows technicians to spot areas where fuel may be leaking or accumulating, indicating a potential failure or defect within the system. Wet spots and stains can often signify that fuel is escaping from a damaged line, fitting, or tank, making visual inspection a crucial procedure in maintenance and safety checks.

While checking the fuel flow rate, monitoring fuel temperature, and listening for unusual sounds can provide valuable information about the overall performance of the fuel system, they are not direct indicators of leaks or defects. Fuel flow rate might reveal inefficiencies but would not specifically pinpoint a leak. Similarly, fuel temperature monitoring helps in assessing operational conditions, and listening for sounds may indicate pump or component issues, but these methods do not visibly confirm the presence of fuel escaping the system. Thus, visual inspection remains the most effective and direct method for identifying internal leaks and defects in aircraft fuel systems.