Which fuels are approved for use in King Air 350 engines?

The King Air 350 engines are specifically designed to operate with kerosene-based fuels, which are critical for turbine engines. Jet A and Jet A-1 are both kerosene-type fuels that provide the necessary properties for turbine engine performance, including proper combustion characteristics and lubrication. Jet B is also a type of kerosene fuel, but it has a lower flash point and is less commonly used than Jet A and Jet A-1, primarily in colder climates or specific conditions.

The other options include fuels that are not approved for use in the King Air 350 engines. For instance, diesel fuel is not suitable for turbine engines due to its different combustion characteristics. Similarly, while 100LL (low lead) avgas is used in piston engines, it is not compatible with turbine engines like those found in the King Air 350. Lastly, 115/145 is a designation for higher-octane avgas used primarily in high-performance piston engines, which again does not align with the operating requirements of the King Air's turbine engines.

Thus, the correct answer reflects the specific fuel types that ensure the proper operation, efficiency, and safety of the King Air 350 engines, which are critical for flight operations.