Propeller Ice Protection
Fluid (slinger-ring) anti-icing and electrical (heater-boot) de-icing, and the anti-ice vs de-ice distinction.
Propeller ice protection — summary notes
Free- Ice on a propeller is doubly harmful: it disturbs the blade aerofoil (losing thrust) and, because it sheds unevenly, it UNBALANCES the propeller and causes heavy vibration — and shed ice can damage the fuselage.
- FLUID (anti-icing) systems pump a freezing-point-depressant fluid (e.g. isopropyl alcohol or TKS) to a slinger ring on the hub; centrifugal force flings the fluid outward along the blades through feed shoes, preventing ice forming.
- ELECTRICAL (de-icing) systems bond heater elements ('boots') to the blade shank/leading edge; current is fed to the rotating hub through slip rings and brushes and cycled by a timer so ice is loosened and thrown off in turn from each blade.
- ANTI-ICE prevents ice forming; DE-ICE lets a little ice build up and then removes it cyclically — propeller electrical systems are usually cyclic de-icers to limit electrical load.
- Slip rings/brushes and the timer are common maintenance items; boots are checked for security and correct heating, and the system is balanced across the blades.
- ⚠ Exam trap: electrical propeller de-icing feeds current to the rotating hub through SLIP RINGS and brushes and cycles heater boots by a TIMER to shed ice in sequence; fluid systems use a SLINGER RING and centrifugal force to distribute anti-ice fluid.
How is electrical power supplied to heater boots on the moving blades, and why is the heating cycled rather than continuous?
Power passes from the stationary engine to the rotating propeller hub through slip rings and carbon brushes, then out to the boots on each blade. The heating is cycled by a timer — energising one blade (or pair) at a time — so that ice is loosened and centrifugally thrown off in sequence, which keeps the total electrical demand manageable and sheds ice evenly to avoid imbalance.
Ice protection concept map
FreePropeller Ice Protection
Propeller ice protection quiz
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