![]() ![]() All ducting should be inspected for security, general condition, or distortion. However, if difficulty arises in locating leaks, a soap-and water solution may be used. The rate of leakage at a given pressure should not exceed that recommended in the aircraft maintenance manual.Īir leaks can often be detected audibly and are sometimes revealed by holes in the lagging or thermal insulation material. Leak checks are made to detect defects in the duct that would permit the escape of heated air. When specified, the ducts should be pressure tested at the pressure recommended by the manufacturer of the aircraft concerned. When installing a section of duct, make certain that the seal bears evenly against and is compressed by the adjacent joint’s flange. These seals are fitted into annular recesses in the duct joint faces. The joined sections of ducting are hermetically sealed by sealing rings. Bellows are located at strategic positions to absorb any distortion or expansion of the ducting that may occur due to temperature variations. In some installations, thin stainless steel expansion bellows are used. The ducting is lagged with a fire-resistant, heat-insulating material, such as fiberglass. The tube, or duct, sections are attached to each other by bolted end flanges or by band-type V-clamps. The ducting of WAI systems usually consists of aluminum alloy, titanium, stainless steel, or molded fiberglass tubes. The hot air is routed through ducting, manifolds, and valves to components that need to be anti-iced. Relatively large amounts of very hot air can be bled off the compressor, providing a satisfactory source of anti-icing heat. Wing Anti-Ice (WAI) SystemThermal wing anti-ice (WAI or TAI) systems for business jet and large-transport category aircraft typically use hot air bled from the engine compressor. There are several sources of heated air, including hot air bled from the turbine compressor, engine exhaust heat exchangers, and ram air heated by a combustion heater. These thermal pneumatic anti-icing systems are used for wings, leading edge slats, horizontal and vertical stabilizers, engine inlets, and more. Thermal Pneumatic Anti-icingThermal systems used for the purpose of preventing the formation of ice or for deicing airfoil leading edges usually use heated air ducted spanwise along the inside of the leading edge of the airfoil and distributed around its inner surface. High-performance aircraft may have “weeping wings.” Large transport-category aircraft are equipped with advanced thermal pneumatic or thermal electric anti-icing systems that are controlled automatically to prevent the formation of ice. Most general aviation (GA) aircraft equipped to fly in icing conditions use pneumatic deicing boots, a chemical anti-ice system. The most common anti-icing systems used are thermal pneumatic, thermal electric, and chemical. The wing leading edges, or leading edge slats, and horizontal and vertical stabilizer leading edges of many aircraft make and models have anti-icing systems installed to prevent the formation of ice on these components. ![]()
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