Props

Propellers often are not well understood by general aviation pilots. Their purpose-transferring the engines horsepower into thrust by moving a large volume of air to the rear-usually is obvious. How this feat is accomplished may not be. Looking at a propeller blade cross-section will reveal it is actually an airfoil, one moving at a right angle to the airplanes desired motion.

A Bartlett

Sunday, April 22, 2018 at 12:00 AM ET

Verified

Key Takeaways:

Propellers, which are airfoils generating thrust, come in various types (fixed-pitch, controllable, constant-speed, feathering), each requiring pilot understanding of their mechanics and hydraulic control.
Thorough preflight inspections, strict adherence to manufacturer maintenance protocols (including specific torque, lubrication, and paint), and immediate attention to operational issues like vibrations or runaway props are crucial for propeller airworthiness and longevity.
Propellers are subject to individual type certificates and Airworthiness Directives, necessitating careful compliance with all associated documentation and procedures to prevent common maintenance errors and ensure safe operation.

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Propellers often are not well understood by general aviation pilots. Their purpose—transferring the engine’s horsepower into thrust by moving a large volume of air to the rear—usually is obvious. How this feat is accomplished may not be. Looking at a propeller blade cross-section will reveal it is actually an airfoil, one moving at a right angle to the airplane’s desired motion.

A closer look will show the actual airfoil section varies with each blade station to provide the most efficient angle of attack for not only the rotational speed but also when considering the aircraft’s forward speed. The blade’s airfoil is thickest at the propeller hub, tapering to a much thinner section at the tip, reflecting the range of airspeeds different portions of the blade experience in operation.