What tool is typically best for detecting leaks in an aircraft fuel tank?

Using a soapy water solution is commonly recognized as an effective method for detecting leaks in an aircraft fuel tank. When applied to the surface around potential leak points, the soapy water creates bubbles that indicate escaping fuel vapors. This method is simple, cost-effective, and can be used in various conditions to identify even small leaks that may not be visible through other means.

While infrared leak detectors can be highly effective for certain types of gases and vapors, they may not be as reliable or practical for fuel tanks specifically. Pressure gauges are useful for checking the integrity of the fuel system under pressure but do not directly reveal external leaks. Visual inspection tools can assist in identifying obvious physical damage or informal leak signs, but they do not offer the same level of sensitivity as a soapy water solution for detecting small leaks where fuel is evaporating or escaping.