Which component helps determine the rotational direction of a propeller blade?

The hub model designation is important in determining the rotational direction of a propeller blade because it often defines the specific configuration and design of the propeller, which includes the rotational characteristics. Different hub designs may be engineered for clockwise (CW) or counterclockwise (CCW) rotation, and this information is critical for proper installation and operation to ensure that the propeller turns in the direction intended by the manufacturer.

Understanding the hub model designation allows mechanics and technicians to select the correct propeller for a specific aircraft engine and its intended performance characteristics. This knowledge is crucial for both safety and efficiency in flight operations. The other options, while relevant to the overall design and performance of the propeller, do not directly indicate the rotational direction as explicitly as the hub model designation does.