Definition
A long, narrow airfoil-shaped component that rotates around a central hub to move air or gas. On a propeller, the blades convert engine power into thrust; in a turbine engine, blades extract energy from hot expanding gases (turbine blades) or compress incoming air (compressor blades).
Plain English
A blade is one of the wing-shaped arms that spins around a central shaft. As it spins, it either pushes air to create thrust (like a propeller blade) or is pushed by moving gas to spin a shaft (like a turbine blade).
Context Anchor
Seen in powerplant and propeller maintenance discussions, especially when inspecting a propeller for damage or describing compressor and turbine parts inside an engine.
Derivation
From Old English 'blæd', meaning 'leaf' — a thin, flat extension. The shape of a propeller or turbine blade resembles a long, curved leaf, which is why the same word is used.
Why Pilots Care
Blade condition directly controls thrust, engine smoothness, and safety; damage causes vibration or power loss.
Intuition Check
Do not think of a blade only as something sharp, like a knife. In aviation, a blade is mainly a shaped surface that moves air or gas.
Example Sentence 1
During preflight, the pilot ran a hand along each propeller blade, checking for nicks or cracks.
Example Sentence 2
Turbine blades inside the engine must survive extreme heat while turning at high speed.