Definition
The sliding blades inside a vane-type pump that ride in slots cut into a rotating central rotor. As the rotor spins inside an offset (eccentric) housing, the vanes slide in and out of their slots, maintaining contact with the housing wall and forming sealed chambers that carry fluid (such as engine oil or fuel) from the inlet side to the outlet side of the pump.
Plain English
Small flat blades that sit in slots on a spinning hub inside a pump. As the hub turns, the blades slide outward to touch the pump wall, trapping fluid between them and pushing it through the pump.
Context Anchor
Seen in discussions of engine-driven vacuum pumps, pressure pumps, and air-powered flight instruments.
Derivation
‘Rotor’ comes from the Latin ‘rotare’, meaning to turn or rotate — the part that spins. ‘Vane’ comes from an Old English word for a flat blade or fin. Together the words describe exactly what the part does: flat blades carried on a turning hub.
Why Pilots Care
These vanes enable the vacuum pump to generate the suction needed for gyroscopic instruments to function reliably.
Analogy
Think of the vanes like small paddles on a spinning wheel. As they turn, they push air along instead of pushing water.
Intuition Check
Do not think of rotor vanes as outside propeller blades. Here, they are internal pump blades that move air inside the pump.
Example Sentence 1
During the engine teardown, the mechanic found that two of the rotor vanes in the vacuum pump had cracked, which explained the gradual loss of suction.
Example Sentence 2
If a rotor vane breaks, the vacuum system fails and the attitude indicator becomes unusable.