Plain English Meaning

When you start an engine by hand-spinning the propeller, the engine sometimes fires at the wrong moment and snaps the propeller backward instead of forward. That backward snap is called kickback, and it can hit the person hard enough to cause serious injury.

Full Definition

A sudden, violent reverse rotation of the propeller during hand propping, caused when the engine fires before the piston reaches top dead center and drives the crankshaft backward. Kickback can throw the propeller blade backward with enough force to break bones or cause serious injury to the person hand propping the engine.

Context Anchor

Seen in hand-propping procedures and safety warnings for starting an airplane engine without using the .