11.12 ICE AND RAIN PROTECTION 👌🏼 Flashcards
3 most common types of ice encountered during flight
- Clear ice
- Rime ice
- Mixed ice
Explain clear ice
- formed by large supercooled water droplets
- freeze gradually
- smooth, hard, glossy, transparent
- heavy and difficult to remove
Explain Rime ice
- formed by small supercooled water droplet
- freezes before it has time to spread
- white appearance
- lighter than clear ice, irregular shape, rough
- brittle but easier to remove than clear ice
Explain mixed ice
- combination of clear and rime ice
List the Ice detection systems
- Visual detection
- Hot rod detector
- Accretion/pressure detector
- Rotary ice detector
- Vibrating ice detector
What are the 2 methods of visual detection
- wing inspection lights
- visual ice indicators
Explain wing inspection lights
- located on each side of fuselage forward section
- enable flight crew to view and detect ice build up
- during night operation or low ambient light conditions in flight
Explain visual ice indicators
- small posts
- usually mounted between windshields
- Ice will be collected on post
Which of the following is a visual ice detector
- hot rod
- pressure operated
- rotary operated
- hot rod ✅
What are Hot rod detectors
- external (where it can be observed by flight crew)
- light illumination for dark conditions
- deicing achieved by heater element within rod
- operated by press button in cockpit
What is a pressure operated ice detector
- 4 holes in leading edge, 2 holes in trailing edge
- leading edge holes blocked by ice and negative pressure is created
- relay closes and triggers ice warning
- relay also activates heating element to melt ice from probe
- when deactivated, probe is able to freeze again until aircraft is out of icing conditions
Explain a rotary ice detector
- external (forward fuselage)
- consists of single phase AC motor
- has knife edge cutter with clearance less than 0.002 inches
- As ice builds up, greater rotational torque is required as it shaved
- This movement gives a ice warning
Explain vibrating probe ice detector
- vibration caused by electric current of approx 40khz
- Ice accumulation on probe causes vibration frequency to decrease
- Flight crew is then alerted
- probes internal and external heater cycles on and off to clear ice accumulation
Which ice detector is NOT built with a heating element?
- Hot rod
- Pressure operated
- Rotary detector
- Rotary detector✅
Which ice detector is de-iced independently?
- hot rod detector
- pressure operated detector
- visual detector
- pressure operated detector✅
Explain Element ice sensing unit (Sangamo Weston ice detector)
- It detects moisture or freezing temp separately to prevent ice formation
3 main components:
- Moisture detector controller
- Moisture sensing head
- Thermal switch
Manufacturers of ice detectors produce sensors that fall under 3 certification types
- Primary automatic
- Primary manual
- Advisory
How are ice detection alerts provided?
- visual or audio alerts in cockpit
- designed to draw FC attention immediately
How are WARNING lights indicated
- corresponding WARNING light is illuminated to notify FC
What must be done when the master caution system is activated
- FC needs to address the situation (has to respond to it)
What are EICAS (Enhanced Indication and Crew Alerting System) ?
- essential engine and system info to FC
- Icing related warnings etc can be displayed on central display
How can a surface be anti-iced?
- keeping it dry
- heating enough to evaporate water
- heating surface to prevent freezing
How can a surface prevent and remove ice?
- heating surface with hot air
- heating by electrical elements
- breaking ice that has formed (inflatable boots)
- applying chemicals to prevent adhesion of ice
What is the preferred anti-ice method on large turbine aircraft
- Thermal pneumatic anti-icing, with engine bleed air
- wing leading edges, empennage, engine inlet cowls