11.12 Ice and Rain Protection Flashcards
What are the three most common types of ice encountered in flight?
Clear
Rime
Mixed
What is clear ice also known as?
Glaze ice
How does clear ice form?
Formed by larger supercooled water droplets, of which only a small portion freezes immediately.
How is rime ice formed?
Small, supercooled water droplets, such as those in stratified clouds or light drizzle, freeze rapidly on contact with a sub-zero surface.
What is mixed ice?
Mix of rime and clear.
What are wing inspection lights for?
Detection of ice.
What is a hot rod detector?
Similar to the ice rod on the front of the windscreen, it is found outside a flight deck window, is heated and lit.
Where is the rotary ice detector mounted?
Forward fuse
How does a rotary ice detector work?
When ice builds up it takes more rotational torque to shave off the ice with the blade from the rotary part.
How does a vibrating ice probe detect ice?
It vibrates at a set frequency, as ice builds up the frequency decreases.
How does a sangamo weston ice detector work?
It detects freezing temps and moisture separately to decide if there is a chance of ice build up.
What three key parts does a sangamo weston ice detector have?
Moisture detector controller
Moisture Sensing Head
Thermal switch
How does a Beta Particle Ice Detection Probe (Sunstrand System) work?
Beta particles are released, and reach a sensor, ice would reduce the amount of particles making it too the sensor.
What is thermal pneumatic anti icing used for?
Leading edges
In the wing anti icing system when does the temperature of the bleed air trigger the overheat warning?
100 °C outboard or 175 °C inboard
How can a surface be anti iced?
Keep it dry
Keep it hot
What does the WAI valve do?
Controls the flow of bleed air from the pneumatic system to the WAI ducts.
In auto how long will the WAI valves stay open?
3 Mins
If an aircraft has EAI (engine anti ice) is it activated before or after WAI?
Beforee
What is weeping wing?
Chemical protection of the wing and stabiliser
What is ice protection based upon?
Freezing point depressant concept
What is the freezing point depressant concept?
An antifreeze solution is pumped from a reservoir through a mesh screen, embedded in the LEs of the wings and stabilisers.
What does the TKS (weeping wing) system contain?
Laser drilled titanium panels with over 800 tiny holes.
How long does the capacity of the TKS system reservoir allow?
1-2 hours of operation
What are the most common component used for de icing wings on small aircraft?
Pneumatic boots
How long are LE boots inflated for?
6-8 seconds
When the de-icing boots are not in use what happens to them?
The vacuum suction keeps them tight to the aircraft.
What PSI does the ice boots deflate at?
17 psi
How can the life of the rubber boots be extended?
By storing the when they are not needed.
How is grease and oil removed from the rubber boots?
Naphtha
Where can chemical de-ice for windshields be found?
Small aircraft
What happens in electrical propellor de-icing if the heat is enough to melt the ice but not evaporate the water?
Runback occurs, causing the melted ice to freeze on other parts of the blade.
How is chemical de icing delivered to the propellors?
Slinger ring
What systems do aircraft use to control rain on the windshield?
Chemical
Pneumatic
Coatings
What is the rainboe system?
Rain repellent system used that has CFC 113
Why is rain repellent now banned?
Because it contains CFC which is ozone depleting.
When and why should rain repellent systems not be used?
Dry conditions, as heavy undiluted repellent restricts window visibility.
Which treatment is a popular repellent?
Hydrophobic coating
What should you not do to hydrophobic coatings?
Apply wax or polish
What is the life of hydrophobic coating effected by?
Wiper blade tension
What does each windshield wiper system consist of?
Wiper, wiper arm and wiper motor.
What is the wiper blade tension?
Then angle at which the blade sweeps across the windshield.
What does the off/park mode do to the wipers?
Sets it to the park/stowed mode.
How many cycles are there in low mode for the wipers?
160 cycles per minute.
How many cycles are there in high mode for the wipers?
250 cycles per minute
