What is the second emergency fuel that is acceptable for use?

The correct answer is 91/96. This fuel type is an emergency fuel suitable for use in scenarios where the primary fuel type is unavailable. In the context of the King Air 350, using 91/96 fuel can ensure continued operation without compromising safety or performance, as it is compatible with the aircraft's engines.

The other fuel options, while they may be used in different aircraft or circumstances, do not hold the same status as acceptable emergency fuels for the King Air 350. Jet A and Jet A-1 are common jet fuels, but they are primarily designed for turbine engines and may not meet the specific requirements or limitations set forth for the King Air 350. Option 505 is also not recognized as an acceptable emergency fuel for this aircraft type, reinforcing the importance of adhering to designated fuel types for safe operation.