Who determines the oil and grease specifications for propeller lubrication?

The correct choice highlights that the propeller manufacturer is responsible for determining the oil and grease specifications for propeller lubrication. This is crucial because propeller manufacturers have specific knowledge regarding the design and materials used in their products. They conduct thorough testing and research to identify the most suitable lubricants that will ensure optimal performance, longevity, and safety of the propellers.

Additionally, the manufacturer's specifications take into account factors such as operating conditions, temperatures, and potential exposure to elements that could affect lubrication. By following these guidelines, users of the propellers can maintain proper lubrication and avoid issues that could arise from using inappropriate lubricants, which may lead to increased wear or even failure of the propeller.

The engine manufacturer might provide general guidelines for compatible lubricants, but when it comes to specific propeller lubrication needs, the propeller manufacturer's recommendations are the authoritative source. The aircraft owner may have responsibilities regarding maintenance, but ultimate specifications must come from the manufacturer of the propeller, who understands the intricacies involved in propeller design and function.