Ice and rain protection, and fire protection systems
Scope
This domain tests ice detection and removal, rain removal, and fire detection and extinguishing. Know the difference between anti-ice and de-ice, protected surfaces, detector types and fire drill actions.
Ice protection
- Anti-ice prevents ice; de-ice removes it. Thermal anti-ice uses engine bleed on wing leading edges and engine intakes. Electro-thermal mats heat pitot, static and TAT probes and the windshield.
- Pneumatic boots inflate to crack and shed ice on the tail or wing, depending on type. Weeping-wing systems distribute glycol.
- Ice types: clear (glaze), rime and mixed. Clear ice is densest and most hazardous.
- Protected areas include wing and tail leading edges, engine intakes, propellers, windshield, pitot/static, TAT and water lines.
Rain removal
- Wipers, rain repellent and, on some types, pneumatic rain removal on the windshield.
Fire protection
- Zones: engine, APU, cargo, cabin and lavatory. Detectors: continuous-loop, thermocouple, optical smoke and ionization.
- The engine fire handle closes fuel, hydraulic and bleed valves and arms extinguisher squibs. Two-shot bottles allow a second discharge.
- Halon 1301 is a clean agent that breaks the combustion chain reaction; CO2 and water/foam are used in some applications.
- Warnings are master warning plus aural and light; always test the system before flight.
Worked example
An engine fire is indicated. The drill is: retard the throttle, pull the fire handle to close fuel, bleed and hydraulic valves, then rotate it to discharge bottle one. If the warning persists after the specified delay, discharge bottle two. Do not reopen the bleed until the fire is confirmed out.
Traps
Boots are de-ice, not anti-ice; never rely on them as anti-ice. Wing anti-ice heats only the leading edge. Halon is not oxygen; do not breathe it. A loop fault can cause a false warning, so use the test.