Definition
The formation and rapid collapse of vapor bubbles in a liquid caused by localized pressure dropping below the liquid's vapor pressure, typically at the inlet side of a pump or on the trailing surfaces of a fast-moving impeller or propeller. The collapsing bubbles produce shock waves that erode metal surfaces and reduce the pump's ability to move fluid.
Plain English
When a pump or impeller is moving liquid so fast that the pressure drops too low, tiny vapor bubbles form in the liquid and then violently collapse. This damages the metal and causes the pump to lose its grip on the fluid.
Context Anchor
Seen in aircraft fuel, oil, and hydraulic system discussions, especially when a pump is not getting a steady supply of liquid.
Derivation
From the Latin cavus, meaning 'hollow.' The bubbles that form in the liquid are literally hollow voids in what should be solid fluid. Knowing this helps the term feel less abstract: a cavitating pump is a pump full of small hollows where liquid should be.
Why Pilots Care
A cavitating fuel pump loses delivery pressure, which can cause engine roughness, power loss, or flameout.
Grounding Statement
Picture a pump that should be moving solid liquid, but instead it is churning liquid full of tiny bubbles.
Intuition Check
Cavitating does not mean the pump is simply sucking air from outside. It means vapor bubbles are forming inside the liquid because the pressure has dropped too low.
Example Sentence 1
The mechanic suspected the fuel pump was cavitating after the pilot reported unstable fuel pressure during high-power climbs.
Example Sentence 2
At high altitude the low fuel pressure caused the auxiliary pump to begin cavitating, dropping line pressure below limits.