At what Ng percentage do secondary fuel nozzles start to occur?

Secondary fuel nozzles begin to activate at 38% Ng, which is crucial for optimizing engine performance and efficiency. The Pilatus PC-12 NG utilizes a single-shaft turbine engine that manages fuel flow based on various parameters, including Ng, or the speed of the gas generator.

At lower Ng percentages, only the primary fuel nozzles are engaged, providing the necessary fuel for the engine's operation under those conditions. As Ng reaches 38%, this specific design allows for additional fuel delivery through the secondary nozzles, enhancing the combustion process and enabling the engine to generate more power as required during different phases of flight, such as takeoff or climbing.

Understanding this operational range is critical for pilots, as it helps them manage engine performance effectively and ensures safe operation of the aircraft under varying flight conditions.