FAA Powerplant Written Practice Test

What fuel types can the non-certified O-233 series engine run on?

1. Only aviation gasoline

2. Biofuel and ethanol

3. Gas or unleaded automotive fuel

4. Diesel and jet fuel

The correct answer is: Gas or unleaded automotive fuel

The non-certified O-233 series engine is designed to be versatile in its fuel compatibility, allowing it to operate on various types of fuels. Gasoline-based fuels, including unleaded automotive fuel, are suitable for this type of engine due to its fuel system and engine design that can handle the properties of such fuels. This adaptability is particularly beneficial for non-certified engines, as it enables pilots and operators to use readily available options that could be less expensive than aviation gasoline, while still providing appropriate performance levels. In contrast, other fuel types are either not compatible with the engine's design or operational characteristics. For example, aviation gasoline is generally used in certified aircraft engines, while biofuel and ethanol may present issues related to engine management, storage stability, and compatibility with materials used in the engine. Diesel and jet fuel are fundamentally different from gasoline and could cause performance problems or even damage the engine, as these fuels have distinct combustion properties and are intended for different engine designs.