What Kind of Fuel Do Piston Planes Use?

Piston planes, also known as piston-engine aircraft, rely on a specific type of fuel to operate efficiently. This fuel is usually aviation gasoline, commonly referred to as avgas, which is specifically designed for these engines. The most widely utilized fuel type for piston planes is 100LL Low Lead, a high-octane aviation gasoline that contains a low level of lead for better performance and to prevent engine knocking.

Understanding 100LL Avgas

100LL Avgas is a high-octane fuel with a lead content of just 0.56 grams per liter, or approximately 2 grams per US gallon. This made it a preferred choice for piston engines due to its ability to maintain performance even when the engine is subjected to different altitudes. The term '100LL' refers to its octane rating, with the '100' representing the lean burn cruise power and the 'LL' indicating the low-lead content.

Compatibility with Mogas

Some piston engines can also be operated using Mogas (motor gasoline), which is standard unleaded automotive gasoline. However, it's important to note that using Mogas is contingent upon specific engine compatibility and regulatory considerations. In some cases, piston engines can be certified to use higher-octane automotive gasoline, such as 93 AKI in the USA or 98/100 RON worldwide, but only if the fuel does not contain any alcohol.

Aviation Diesel Piston Engines

In recent years, the aviation industry has seen a growing trend toward diesel-powered engines. These engines are generally designed to use aviation turbine fuel, also known as Avtur or Jet A. This fuel is the same kerosene-based substance used by jet engines, making it widely available wherever jet fuel can be purchased.

Small Engines and Alternative Fuels

For smaller piston engines, particularly those under 200 horsepower, it's possible to obtain a Supplemental Type Certificate (STC) to allow their use of higher-octane automotive gasoline, similar to 93 AKI in the USA or 98/100 RON worldwide. However, it's crucial to ensure that the fuel contains no alcohol, as this can cause compatibility issues.

Experimental and Uncertified Aircraft

Aircraft that are experimental in nature, ultralights, or uncertified can run on the fuel that their engines are specifically designed for, further highlighting the flexibility and adaptability of modern aviation fuels.

Conclusion

The choice of fuel for piston planes is a critical decision, influenced by the type of engine and its specific requirements. Whether it's the high-performance 100LL Avgas, the versatile Mogas, or the increasingly popular aviation diesel with Avtur, understanding the correct fuel selection is essential for safe and efficient operation of these aircraft.