What does the green arc on the cabin differential pressure gauge represent?

The correct answer indicates that the green arc on the cabin differential pressure gauge represents a range from 0 to 6.6 PSI. This range is significant because it defines the optimal operating limits for cabin pressure during flight in the King Air 350 aircraft.

In this context, the green arc visually shows the acceptable pressure differential that ensures passenger comfort and safety at various altitudes. A differential pressure exceeding this value could suggest that the cabin is not adequately pressurized, which may lead to uncomfortable or even unsafe conditions for those on board.

Understanding the various arcs on the differential pressure gauge is critical for pilots, as it helps them monitor cabin pressure throughout various phases of the flight. It's essential for ensuring that the aircraft operates within its designed parameters, thus maintaining safety and comfort. The other options reflect ranges that are not applicable to the King Air 350, as they either exceed the maximum safe operating pressure or fall below the minimum necessary for effective cabin pressure management.