Which three parts of a rotary wing aircraft should be avoided at all times?

The main rotor blades, tail rotor blades, and cargo hooks present significant safety hazards on a rotary wing aircraft, which is why they should be avoided at all times.

The main rotor blades are responsible for generating lift, and if a person gets too close during operations, they risk severe injury or even fatality due to their high speed and rotation. Similarly, the tail rotor blades also rotate at high speeds and facilitate the aircraft's control and stability; thus, proximity to them poses a severe danger. Cargo hooks, which are part of the external load system, can also be perilous, particularly when they are in use, as they may swing or drop loads unexpectedly.

The other options, while they may include components that require caution, do not encompass the immediate physical dangers presented by the main and tail rotor blades and cargo hooks during aircraft operations. It’s essential to prioritize safety around these areas to ensure the well-being of personnel and the successful operation of the aircraft.