During preflight the remote pilot finds a propeller with a small nick along the leading edge. What is the appropriate action?

A propeller is a rotating airfoil turning at very high speed, and it depends on being both balanced and structurally intact. A nick along the leading edge does two things: it disrupts the airflow over that blade so it produces slightly different thrust from its opposite number, and it introduces a stress concentration where a crack can begin. The imbalance produces vibration, which is transmitted into the motor bearings, the airframe and the camera gimbal, degrading image quality and accelerating wear. The crack risk is the serious one, because a blade failing at operating speed produces an immediate and total loss of control. Propellers are inexpensive and designed to be replaced, so the risk calculus is entirely one-sided. Filing the nick smooth removes material and worsens the imbalance rather than curing it, and reducing payload does nothing about a structural defect. Part 107 prohibits operating an aircraft with a discrepancy affecting safe operation, and this is one.

A nick disrupts the blade's airflow and creates a stress concentration, producing vibration and the risk of blade failure at operating speed. Replacement is the only sound response.

Part 107 prohibits operating a small unmanned aircraft with a known discrepancy affecting safe operation. Propeller damage causes imbalance and vibration and creates stress concentrations that can lead to blade failure.

Cheapest Part, Worst Failure. A blade letting go at speed is an immediate loss of control.

Vibration also degrades gimbal stabilisation, so unexplained image judder is a reason to inspect the propellers.

• •Dressing or filing damage rather than replacing the propeller
• •Treating propellers as outside the airworthiness requirement
• •Replacing one blade where the manufacturer specifies sets