What does the power lever setting indicate for autofeather system activation?

The power lever setting is crucial for determining the conditions under which the autofeather system is activated. This system is designed to optimize engine performance and safety during flight by automatically feathering the affected propeller when an engine failure occurs.

For the autofeather system to engage effectively, the power lever setting must indicate a specific range of N1, which is the rotational speed of the engine's low-pressure compressor. When the power lever is set above approximately 90% N1, it signifies that the engine is producing a substantial amount of thrust. If a failure occurs in that regime, the autofeather system activates to reduce drag and improve the aircraft's performance, enabling it to maintain better control and speed.

This threshold helps to ensure that the system does not activate under circumstances where feathering is unnecessary, such as during normal operations at lower power settings. The other choices do not align with the operational requirements for the autofeather system, as they either indicate power levels that are too low or at full throttle where it may not be an appropriate moment for feathering actions.