What is the function of the C-switch at 35%?

The C-switch at 35% serves the specific function of turning off the starter motor. In many aircraft systems, including those that involve jet propulsion, the starter motor is engaged during the initial phase of engine start-up to provide the necessary rotation for engine ignition. Once the engine reaches a certain speed, typically around 35% of the operational RPM, the function of the starter motor is no longer needed. At this point, the C-switch disengages the starter motor, preventing potential damage due to excessive running and ensuring that the engine can operate under its own power. This action is crucial for both operational efficiency and the longevity of the engine components.