Definition
The large, aerofoil-shaped blades mounted on the rotating disc at the front of a turbofan engine. They draw a large mass of air into the engine, accelerate it rearward, and produce most of the engine's thrust by directing the majority of that airflow around the core rather than through it.
Plain English
The big spinning blades you can see at the front of a jet engine. They pull air in and push it backward, which is what produces most of the engine's pushing power.
Context Anchor
Seen in jet engine basics, engine inlet inspections, and discussions of how turbofan engines make thrust.
Derivation
From the everyday word 'fan' -- a device that moves air. The aviation use is the same idea, just much larger and stronger: a powered fan that moves an enormous volume of air to produce thrust.
Why Pilots Care
Understanding fan blades helps pilots recognize how turbofan engines produce efficient thrust and why damage to them affects performance and safety.
Intuition Check
Do not think of fan blades as a cabin cooling fan or as propeller blades mounted on the airplane. In this context, they are internal jet engine parts that move a large amount of air through and around the engine.
Example Sentence 1
During the walkaround, the pilot inspected each fan blade for nicks, cracks, or signs of impact damage.
Example Sentence 2
On takeoff the fan blades accelerate large amounts of air to provide the primary thrust.