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.
Plain English
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.
Context Anchor
Seen in hand-propping procedures and safety warnings for starting an airplane engine without using the starter.
Derivation
From 'kick' (a sudden forceful motion) and 'back' (reverse direction). The word describes exactly what happens: the propeller kicks back toward the person turning it, instead of continuing forward as expected.
Why Pilots Care
A kickback can cause serious injury to the person hand-propping; awareness drives correct body position and safety margins outside the propeller arc.
Grounding Statement
Picture pulling a propeller blade through to start the engine, and instead of continuing forward, the blade suddenly jerks back toward you.
Intuition Check
Kickback does not mean a small bounce or vibration here. It means a sudden backward snap of the propeller that can be dangerous.
Example Sentence 1
The instructor warned the student that hand propping a hot engine increases the risk of kickback.
Example Sentence 2
After the propeller kicked back, the student stepped clear and waited for the engine to stop before attempting another start.