Final answer:
Draining fuel from fuel sumps prevents water and contaminants from causing engine problems. It is similar to extracting pure substance from an impure mix, as in removing water from wet sand. This process is vital for safety and functionality of engines.
Step-by-step explanation:
Draining fuel from the fuel sumps is necessary to ensure that water and contaminants do not accumulate in the fuel system, which could lead to engine problems or failure. For example, the process of fuel extraction can be likened to getting water out of wet sand, indicating that there are various impurities that can contaminate fuel, just as water can be trapped in sand.
In aviation, this practice is also essential as any contaminants in the fuel, such as water, can freeze at high altitudes and block fuel lines. Another example is provided by the concept of Flow-Through in a ballast tank, where the tank is flushed to clear it of pollutants; similarly, fuel sumps must be drained to remove impurities and maintain clean fuel in the system.
The underlying principle is to prevent the build-up of substances that could compromise the functionality and safety of an engine, whether in vehicles or aircraft. If not drained regularly, these impurities can cause damage to the engine or negatively affect the combustion process.
Additionally, draining the fuel sumps allows for better fuel efficiency and helps ensure the proper functioning of the fuel system.