In what situation is the operation of the autofeather circuit most critical?

The operation of the autofeather circuit is most critical during takeoff and landing because these phases of flight involve the highest demand on engine performance and are critical for safety. During takeoff, if an engine fails, the autofeather system automatically adjusts the propeller of the inoperative engine to minimize drag, helping the aircraft maintain optimal performance and control. Similarly, during landing, a loss of engine power can lead to a significant reduction in the aircraft's performance, making the autofeather system essential for ensuring that the aircraft can be safely maneuvered and controlled during descent and approach. The critical nature of engine performance during these phases of flight underscores the importance of having an operational autofeather system to enhance safety and performance.