Ice & Rain Protection
Thermal anti-ice, pneumatic de-ice boots, electrical probe/windshield heating and rain removal.
Ice & rain protection, summary notes
- ANTI-ICING prevents ice forming; DE-ICING lets a little ice build up then removes it. Wing and engine-cowl leading edges on jets are usually ANTI-iced with hot engine BLEED AIR (thermal), keeping the surface above freezing.
- PNEUMATIC BOOTS (mostly turboprops) are cyclic DE-icers: rubber boots on the leading edge inflate to crack off accumulated ice, then deflate.
- ELECTRICAL heating protects pitot/static, angle-of-attack and total-air-temperature PROBES, windshields, water lines and (via slip rings) propellers.
- RAIN removal uses windshield wipers, chemical rain repellent and hydrophobic coatings; ICE DETECTION warns the crew or auto-activates protection.
- For the B2 technician the heater elements, timers, control valves, ice detectors and their indication are the focus.
- ⚠ Exam trap: wing/cowl anti-ice normally uses hot BLEED AIR (thermal); pneumatic BOOTS are cyclic DE-icers that inflate to break ice off after it forms; pitot and static probes are ELECTRICALLY heated.
Why are pitot and static probes electrically heated rather than protected by bleed air like the wing?
The probes are small, precision sensors that must stay exactly ice-free to give correct air-data readings, and routing hot bleed air to each little probe would be impractical and could disturb the measured pressures. A small electrical heating element built into each probe keeps it above freezing simply and reliably, with the heat controlled and monitored, hence 'probe heat' checks before flight.
Ice & rain protection concept map
Ice & Rain Protection
Ice & rain protection quiz
Ice & Rain Protection, quiz
1. Wing and cowl anti-ice on jets usually uses:
Hot engine bleed airPneumatic bootsChemical fluid only2. Anti-icing differs from de-icing in that anti-icing:
Prevents ice formingRemoves ice after it formsOnly detects ice3. Pneumatic de-icing boots work by:
Inflating to crack accumulated ice offHeating continuouslySpraying fluid4. Pitot and static probes are protected by:
Electrical heatingBleed airPneumatic boots5. De-icing boots are cycled (ice allowed to build) to avoid:
Ice bridging over the bootOverheatingFuel loss6. Rain is removed from the windshield by:
Wipers, repellent and coatingsBleed air onlyThe fuel system7. Windshields are also:
Electrically heated for anti-ice/demistCooled by bleed airLeft unprotected8. An ice-detection system:
Warns the crew or auto-activates protectionSets the thrustMeasures fuel