Definition
The central structural component of a propeller assembly that mounts to the engine crankshaft and holds the propeller blades in place. The hub transmits engine torque to the blades and, on adjustable or constant-speed propellers, contains the mechanism that changes blade pitch.
Plain English
The solid center of the propeller. The blades attach to it, and it bolts onto the front of the engine so the engine can spin the whole propeller.
Context Anchor
You will encounter this term when studying propeller construction, preflight inspection, and discussions of how engine power is transferred to the propeller.
Derivation
Hub comes from an old English word for the center of a wheel — the solid middle that the spokes attach to. The propeller hub does the same job: the blades radiate out from it like spokes from a wheel.
Why Pilots Care
Damage or imbalance in the hub can cause vibration, loss of propeller control, or in-flight separation, directly affecting safety and airworthiness.
Intuition Check
The propeller hub is not the whole propeller. It is the central connecting part that holds the blades and attaches them to the engine.
Example Sentence 1
During preflight, the pilot wiped the propeller hub and checked for any signs of oil leakage around the blade roots.
Example Sentence 2
The mechanic torqued the bolts that secure the propeller hub to the crankshaft flange.