If the engine does not accelerate to idle RPM and fails to respond to throttle input during start, what is your first action?

The correct action in the scenario where the engine does not accelerate to idle RPM and fails to respond to throttle input during start is to stop the start. This action is crucial because continuing the start process could lead to further complications such as a potential engine fire or damage to the engine. Stopping the start allows the crew to assess the situation and take appropriate steps to ensure safety, such as performing system checks or initiating emergency procedures if necessary.

In scenarios like these, safety is the priority, and pausing the start sequence enables the flight crew to prevent additional risks associated with an unresponsive engine. It also provides the opportunity to troubleshoot or consult relevant checklists or guidelines as outlined in the operating procedures for the C-17. Properly handling situations where the engine fails to respond ensures the aircraft's systems are monitored and managed effectively, enhancing overall operational safety.