What is the primary purpose of a fuel tank sump?

The primary purpose of a fuel tank sump is to provide a designated location where contaminants such as water and dirt can accumulate and be drained away from the fuel system. In aviation fuel systems, maintaining fuel quality is crucial, as any contaminants can lead to engine performance issues or failure. The sump acts as a trap for these impurities, ensuring that only clean fuel is used by the engine. Regularly checking and draining the sump helps to maintain the integrity of the fuel system and enhances overall safety. This process is essential in preventing issues such as fuel tank icing, which can occur if water accumulates and freezes, obstructing fuel flow.