11.12 ICE AND RAIN PROTECTION 👌🏼 Flashcards

1
Q

3 most common types of ice encountered during flight

A
  • Clear ice
  • Rime ice
  • Mixed ice
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2
Q

Explain clear ice

A
  • formed by large supercooled water droplets
  • freeze gradually
  • smooth, hard, glossy, transparent
  • heavy and difficult to remove
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3
Q

Explain Rime ice

A
  • 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
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4
Q

Explain mixed ice

A
  • combination of clear and rime ice
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5
Q

List the Ice detection systems

A
  • Visual detection
  • Hot rod detector
  • Accretion/pressure detector
  • Rotary ice detector
  • Vibrating ice detector
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6
Q

What are the 2 methods of visual detection

A
  • wing inspection lights
  • visual ice indicators
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7
Q

Explain wing inspection lights

A
  • 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
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8
Q

Explain visual ice indicators

A
  • small posts
  • usually mounted between windshields
  • Ice will be collected on post
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9
Q

Which of the following is a visual ice detector
- hot rod
- pressure operated
- rotary operated

A
  • hot rod ✅
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10
Q

What are Hot rod detectors

A
  • 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
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11
Q

What is a pressure operated ice detector

A
  • 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
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12
Q

Explain a rotary ice detector

A
  • 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
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13
Q

Explain vibrating probe ice detector

A
  • 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
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14
Q

Which ice detector is NOT built with a heating element?
- Hot rod
- Pressure operated
- Rotary detector

A
  • Rotary detector✅
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15
Q

Which ice detector is de-iced independently?

  • hot rod detector
  • pressure operated detector
  • visual detector
A
  • pressure operated detector✅
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16
Q

Explain Element ice sensing unit (Sangamo Weston ice detector)

A
  • It detects moisture or freezing temp separately to prevent ice formation

3 main components:
- Moisture detector controller
- Moisture sensing head
- Thermal switch

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17
Q

Manufacturers of ice detectors produce sensors that fall under 3 certification types

A
  • Primary automatic
  • Primary manual
  • Advisory
18
Q

How are ice detection alerts provided?

A
  • visual or audio alerts in cockpit
  • designed to draw FC attention immediately
19
Q

How are WARNING lights indicated

A
  • corresponding WARNING light is illuminated to notify FC
20
Q

What must be done when the master caution system is activated

A
  • FC needs to address the situation (has to respond to it)
21
Q

What are EICAS (Enhanced Indication and Crew Alerting System) ?

A
  • essential engine and system info to FC
  • Icing related warnings etc can be displayed on central display
22
Q

How can a surface be anti-iced?

A
  • keeping it dry
  • heating enough to evaporate water
  • heating surface to prevent freezing
23
Q

How can a surface prevent and remove ice?

A
  • heating surface with hot air
  • heating by electrical elements
  • breaking ice that has formed (inflatable boots)
  • applying chemicals to prevent adhesion of ice
24
Q

What is the preferred anti-ice method on large turbine aircraft

A
  • Thermal pneumatic anti-icing, with engine bleed air
  • wing leading edges, empennage, engine inlet cowls
25
Explain thermal pneumatic anti-icing
- prevents ice formation on aero foil LE - warm air enters duct which travels lengthwise along inside of leading edge of aero foil and exits through holes
26
Explain wing anti-ice (WAI) system
- Thermal wing anti-ice utilise hot air from engine bleed - hot air routed through ducting, manifolds, and valves to LE of the wings - joints of ducting is ‘hermetically sealed’ to prevent loss of hot air
27
Explain the WAI valve
- controls flow of bleed air from pneumatic system to WAI ducts - electrically controlled and pneumatically actuated -
28
What information is shown on WAI indication system
- WING MANIFOLD PRESS - VALVE - AIR PRESS - AIR FLOW
29
Explain engine anti-ice (EAI)
- large turbine powered aircraft have thermal pneumatic engine (inlet cowl) - bleed air is ducted to LE of engine inlet cowls, and then exits through overboard vents
30
Explain pneumatic de-ice boots
- commonly used for de-icing wings and stabilisers on small/reciprocating engines - expand when pneumaticcally inflated, breaking away any formed ice - Boots inflated 6-8 seconds then deflated by vacuum suction
31
Explain electric de-ice boots
- contain electric heating elements which are bonded to leading edge - when activated, boots heat up and melt ice
32
What systems are used to control rain on windshield
- Chemical rain repellent - Pneumatic rain removal (Jet blast) - hydrophobic surface seal
33
Explain windshield surface coating
- ‘hydrophobic’ coating (layer that repels water) - long term
34
Explain pneumatic rain removal systems
- removes rain by directing a flow of heated air over windshield
35
What 2 purposes do heated air serve in a pneumatic rain removal system
- breaks raindrop into small particles - heats windshield to prevent moisture from freezing
36
In pneumatic rain removal systems, how can the air be supplied
- electric blower - bleed air
37
Explain probe anti-ice
- current flows through integral conductive element that generates heat - temp of system kept above freezing point of water
38
Aircraft with water and waste systems have ———- to prevent ice from forming in water lines
- electrical heaters
39
What does a windshield wiper assembly consist of
- a wiper - a wiper arm - a wiper motor
40
Windshield wiper systems are powered by
- electrical motors - hydraulic motors (old aircraft)