Aircraft icing Flashcards
Three main types of Airframe icing:
Rime ice
Clear, ice
Mixed ice
Rime ice
This is formed by the instantaneous freezing of small, super cold water. Droplets skin temperature must be less than 0°C.
Forms in layer – type of clouds, such a stratus. Not very adhesive, and Bridal. Most commonly resulting in light to moderate levels of icing.
Clear, ice
Formed when large, super cold water, droplets slowly freeze to the aircraft skin skin temperature, less than 0°C. Smooth and transparent. The most dangerous type of icing!
Larger accumulations are characterized by the presence of upper and lower horns
Mixed ice
This is a combination of rime and clear ice
What three things have an effect on the rate of ice accumulation?
Airfoil shape
Airfoil size
Droplet size
What type of aerofoil shape collects ice quicker
A thin airfoil collects ice, more efficiently than a thick one
Does the speed of an aircraft affect the accumulation of ice?
Yes, the higher airspeed the greater rates of accumulation
Does droplet size affect the ice accumulation on an airplane?
Large droplets, require strong, vertical currents to overcome gravity, so vertically developed clouds, what has larger droplets. A larger water drop that will be more likely to strike the wing and a smaller droplet clouds with larger liquid contact will have a greater icing intensity. This means that clouds and warmer air masses are more suspect.
Four types of icing intensity
Trace
Light
Moderate
Severe
Trace icing
It is not hazardous, even without the icing or anti-icing equipment, unless it is encounter for an extended period of time more than one hour
White icing
In this environment, the rate of accumulation may create a problem if the flight is prolonged over one hour
Moderate icing
In moderate icing conditions, the rate of accumulation is quick enough, that even short encounters will be potentially hazardous
Severe icing
The rate of accumulation is fast enough to render deicing or anti-icing equipment useless. An immediate diversion is necessary.
What should I do when I encounter icing
Make an immediate decision. Climb or descend, or go back.
What are some effects of aircraft icing?
Overall, the Aircraft-Performance will decrease. There will be an increase in drag, which requires more power to sustain flight. A decrease in power available from the intake blockage. Engine failure due to car pricing for blocking of the air and take.
More effects of aircraft icing
Icing alters the shape of the wing, which will cause an increase in stall speed. The angle of attack at which the stall occurs is decreasing, which means the stall speed is increasing.
How does frost effect an aircraft?
Frost disrupts the air flow over the wing, thereby increasing the stall speed. When lift is reduced by 30% and drag is increased by 40%.
What are the critical surfaces on an airplane?
Wings
Control surfaces
Rotors/propellers
Horizontal stabilizer’s/vertical stabilizer’s
Upper surface of fuselage in the rear mounted engine
Any other stabilizing surface of an aircraft
Aircraft icing – CARS
No person may attempt to contact to takeoff in any aircraft that has frost, ice, or snow, adhering to any of its critical surfaces
