Which of the following is a typical indication of a fuel leak in an aircraft?

A typical indication of a fuel leak in an aircraft is visible stains and a fuel odor. When there is a fuel leak, it often manifests as liquid pooling around the area where the fuel is leaking, leading to noticeable stains on the aircraft's structure. The smell of fuel is another critical indicator; it alerts personnel and crew members to the presence of a fuel leak, which can pose significant safety hazards.

In aviation, immediate detection of fuel leaks is crucial because they can lead to severe consequences, including fire hazards and operational inefficiencies. Catching signs of a fuel leak in this manner allows for prompt corrective action before the situation escalates.

Other indicators, like engine overheating, excessive engine vibration, or low engine RPM, can be symptoms of various operational issues unrelated to fuel leaks specifically. While these symptoms can certainly affect the engine's performance and overall safety, they do not directly indicate a fuel leak in the way that visible stains and fuel odor do.