Ice and Rain Control Systems Flashcards
Describe the operating principle of inflatable deicer boots.
Pneumatic deicing systems use rubber inflatable boots attached to the leading edge of the wings and stabilizers. During operation, the tubes are inflated with pressurized air, and deflated in an alternating cycle. This inflation and deflation causes the ice to break off, and it is carried away by the airstream.
What are two methods of inflating pneumatic deicer boots?
Pressurized air is provided by an engine driven air pump (vacuum pump), or by bleed air form a turbine engine compressor.
What methods are sued to attach deicer boots to the leading edges of wing and tail surfaces?
Bonding to the surface with cement, fairing strips and screws, or a combination of both methods.
What is the purpose of an air-oil separator in a pneumatic deicing system?
The purpose of removing the oil form the air of the deicing system is to prevent deterioration of the rubber deicing boots caused by contact with the oil.
What is used to clean deicer boots?
A mild soap and water solution.
What must be done before you can make a cold patch repair to a deicer boot?
The deicer boot must be relieved form its installed tension before applying the patch.
What component of a pneumatic deicer system normally allows suction to be supplied to the boots for hold down in flight
The solenoid distributor valve.
Describe the operating principle of thermal anti-icing systems.
Thermal anti-icing systems are used primarily for the purpose of preventing ice from forming on the leading edges. However, they are designed to also deice the leading edges by supplying much hotter than normal air for short periods on a cyclic system. The airfoils that are to be protected are usually provided with closely spaced double skin. The hot air is passed through the space between skins, and the heat is sufficient to prevent formation of ice or to melt any ice next to the skin. The heated air is supplied continuously as long as the anti-icing system is turned on.
What methods are used to supply heated air for thermal anti-icing systems?
Bleed air from the turbine engine compressor, engine exhaust heat exchangers and ram air heated by a combustion heater.
How is overheating prevented in a thermal anti-icing system using bleed air?
A thermal switch will cause a shut-off valve to close and stop the flow of bleed air when the temperature of the leading edge reaches approximately 185°F. When the temperature drops, the valve opens, and hot bleed air enters the wing once again.
In a thermal anti-icing system, what happens to the air after it has heated the leading edge of the wing?
The air is then exhausted to the atmosphere at the wingtip or at points where ice formation could be critical.
What problems are associated with electrically heated windshields?
Delamination, arcing, scratches, and discoloration.
What is windshield delamination?
Delamination is the separation of the plies.
What does arcing usually indicate in an electrically heated windshield?
Arcing usually indicates that there is a breakdown in the conductive coating.
What type of power is used to operate windshield wiper systems?
Electrical or hydraulic power.
