Definition
A system that prevents ice from forming on the leading edges of propeller blades by continuously distributing a freezing-point depressant fluid (typically isopropyl alcohol or a glycol-based fluid) onto the blades while the aircraft is operating in icing conditions. The fluid is fed from a tank through a pump to a slinger ring on the propeller hub, then flung outward along the blades by centrifugal force.
Plain English
A system that keeps ice from forming on the propeller blades in the first place by spraying a special fluid onto them during flight in icing conditions.
Context Anchor
Seen in aircraft icing equipment, cockpit anti-ice controls, preflight checks, and maintenance descriptions for propeller-driven aircraft approved for flight in icing conditions.
Derivation
Anti- comes from the Greek 'anti', meaning 'against' or 'preventing'. An anti-icer prevents ice from forming, as opposed to a de-icer, which removes ice that has already formed.
Why Pilots Care
Maintains propeller efficiency and thrust while avoiding vibration or blade damage from ice accumulation.
Intuition Check
A propeller anti-icer is not mainly a tool for chopping off a large ice buildup after it has formed. Its job is to prevent ice from forming or keep it from getting established on the blades.
Example Sentence 1
Before entering the cloud layer at the freezing level, the pilot switched on the propeller anti-icer to keep ice from forming on the blades.
Example Sentence 2
During the preflight inspection the mechanic confirmed the anti-icer fluid reservoir was full.