Progress Test 10 Flashcards
(33 cards)
How can ice have an effect on an aircraft?
Name four ways.
- Increase the weight
- alteration to the center of gravity
- Increase in drag
- cause vibrations in the form of weight imbalance of the aircraft
What key aircraft systems could be effected by ice?
Pitot and static ports. It can also block air intakes
Snow can effect the visibility, how can snow or ice effect the aerodynamics?
Spoils the aerodynamic shape of the wing.
lack of thrust due to the loss of the aerodynamic shape of the propeller.
True or False? General Aviation legally are not designed with anti ice system’s.
True.
When are icing conditions generally found and when typically are the icing conditions worse?
Found in in clouds with temperatures of less than 0 degrees. The freezing level can be found on forecast charts. the worst icing condition occur from 0 degree to -12 degrees.
Water can exist in clouds as super cooled water droplets, what happens when water droplets come in contact with sub-freezing surfaces?
The water droplets freeze immediately, when water flows over the airframe ice builds up over the aerodynamic surface increase drag and weight.
What are the four type of icing classification?
Trace, Light, Moderate and Severe.
With Trace icing conditions the accumulation of ice is slightly greater than the loss, at what point will trace icing conditions become hazardous?
When encounted for longer than an hour.
Light icing conditions require occasional use of the de-icing equipment, the rate of accumulation may create a problem after one hours. Should de-icing and change in altitude/heading be required?
No.
What is the rate of moderate icing accumulation and what is required?
The rate of accumulation is such that short encounters become potentially hazardous. De-icing/anti-icing equipment are required to permit and remove accumulation, or heading/altitude change.
Severe icing requires immediate change in heading and altitude or a diversion, how much effect will de-icing equipment have at this time?
Little effect due to the mass accumulation of ice and anti-icing will have little effect.
What are the symbol for moderate and severe icing conditions?
Moderate is a U shape with two vertical lines.
Severe is a U shape with three vertical lines.
What level of icing can clouds have when they can hold larger water droplets at lower altitudes, what clouds are likely to have this?
They tend to have severe icing conditions, Cumulus and Orographically formed clouds.
What is Rime Ice?
(Impact Ice) Is formed by water droplets impacting the airframe, they are brittle and semi-opaque due to trapped air.
Clear ice forms as water droplets behind the Rime Ice, what are it’s characteristics?
Denser (more weight), difficult to remove and often get to parts of the airframe that are not protected by anti-ice.
What type of icing is formed by Sublimation (the transfer of particles from a gas straight to a solid on a surface that is less than 0 degrees)
Hoar Ice. This can dramatically effect aerodynamics.
Hoar Ice, forms at early parts of the morning on structures. When else can this form and what are the effects?
can form in flight when flying through different air masses. Can happen at cruise at a level that is 0 degrees or below, the airframe becomes cold so will need to move into warmer air by descending.
True or False? Rain Ice is solid frozen rain falling straight from the clouds.
False. Water droplets become super cooled and when they hit a structure then they freeze, can be very difficult to remove.
What Front is Rain Ice associated with?
Associated with warm front where the rain falls into the cold air sector from the warm sector.
The carburettor mixes fuel with air, what is the ‘butterfly valve’ do and what does it control?
The butterfly valve is the throttle and it controls how much of the fuel and air mixture is let into the engine.
Bernoulli’s principle works with the carburettor by employing a venturi tube to decrease the pressure to draw the fuel into the air flow, how does the Venturi tube have an effect on the dew point?
-Venturi creates a drop in pressure which suddenly decreases the dew point temperature
-Air with reduced pressure cannot support the amount of water vapour at high pressure
-If the dew point decrease enough water vapour can condense
The temperature is reduced further due to evaporation of fuel at the Venturi, for fuel evaporation to occur what happens?
Energy is required for fuel to vaporise which comes from the temperature, when the temperature decreases it will results in evaporation.
What is the temperature of air inside a carburettor Venturi?
25-30 degrees Celsius
Ice forming in the Venturi will restrict the fuel to air mixture to the engine by restricting the butterfly valve, what temperature can ice occur?
Any temperature.
