Ice And Rain Protection Flashcards
(21 cards)
When does ice occur
Air and a temperature where the moisture strikes aircraft at 0 degrees Celsius or colder
Water can be remained in a liquid at 0 degrees Celsius. What’s this called
Super cooled
Classifications of ice are:
- Trace - not hazardous to aircraft. Does not need clearing unless it accumulates for periods of one hour
- Light - may cause problems to aircraft that fly through icing zones for over one hour and allowed to build up
Ice protection equipment will readily remove this - moderate - problem even in short encounters
De icing and anti icing
4 . Severe - most hazardous
Cause malfunction
Diversion away from the icing zone is highly recommended
Critical icing areas
1.Aerosol surfaces
2.engine intakes and internal surfaces
3.rotoe blades and propellers
4.windscreen/canopies
5.pilit probes and static vents
6.control surfaces
7.weapons and weapon carriers
Icing hazards and effects
- Increased in fuel consumption reducing aircrafts range and speed
- Reduced tak off/climb performance and manoeuvrability
- Increase in stall speed resulting in an increase in landing speed and distance
- disturb instrument readings
- Can cause severe vibrations
Rotor blade icing
Faster moving tip comes into contact with many more super cooled water droplets = rapid build up of ice
Shedding of ice
Ice would fall of blades at different times causing severe vibrations ( asymmetricaly )
Dangerous to the ground crew when they fall off
Protective covers
Intake blanks , pilot head covers , and air conditioning bungs
All should be a good tight fit
Covers should not be fitted when aircraft is water wet. Adhesion will occur
Should not be covered over snow or ice
Should not be fitted if the aircraft is to hot
Visual ice detector
Majority of the aircraft is equipped with flood lights aligned to illuminate areas which are visible from cockpit and there is a heater which can be turned on. For parts that can’t be seen or weather is bad it’s built with probes which will tell the pilot it’s icy
Pressure differential ice detector
Has 4 holes at the top and if they get covered the pressure (between the two edges) builds up which then indicates that it’s icy and is heated
Icing condition monitor
Has:
moisture sensing head - sense temp change
Moisture detector controller - if there’s alot of moisture
Thermal switch - tells you if you are at 0 or below 0
Then tells you it’s icy
Detects if it’s in the conditions for ice to form
Active system (2)
Anti-icing = prevents the formation of ice *** this one is better
De-icing = removes ice
Passive system
Harness the momentum of the main airstream to separate out precipitation and divert it away
De icing is
Utilise more than one type of system
De-icing systems tend to be lighter and use less energy
Engine aircraft intake
The principle of operation is to force the air stream to make sharp changes in direction and therefore the velocity
Due to water having a higher mass it causes them to separate from the main airstream so air goes one way (engine) and water particles go the other
Thermal (hot air) airframe
Utilises hot air bled from the engine compressors
Hot air is fed through system which reduces pressure and temp of the air to operating levels
The controlled air is then ducted through galleries to relevant areas (leading edges )
Thermal (electrical)
Used for both anti-icing and de-icing systems when complex control arrangements are needed, or only small areas require to be heated
Mechanical (pneumatic) rubber on the leading edge
Rubber boots attached with glue
They inflate so it just cracks the ice off
Windscreen ice protection
De icing fluid
Heated windscreens
Windscreen rain protection
Windscreen wipers are fitted
Windscreen screen wiper general maintenance
Replace rubber blades when :
Worm to limits
Damaged
Contaminated
Routine lubrication of the system
Checks for clearance between blades and screen
Checks for correct tension
