Oil and grease specifications for lubrication of propellers are determined by which party?

• A. FAA
• B. Propeller manufacturers
• C. Engine manufacturers
• D. Aircraft owner/operator

Answer: (B)

Lubrication requirements for a propeller are defined by the propeller manufacturer because the lubricant must be matched to that specific design. The maker designs and tests the hub, bearings, seals, and lubrication channels, and certifies which lubricants and viscosities work with its materials and tolerances. Using a lubricant outside those specifications can affect seal performance, heat dissipation, and bearing life, and could compromise safety or void the propeller’s certification. The broader aviation authorities set general airworthiness standards, but they don’t specify exact lubricants for each propeller installation. Engine manufacturers provide oil specs for the engine itself, not the propeller’s lubrication system, and the maintenance manual from the propeller maker tells you the exact lubricant type, grade, and service intervals to use.