Types of Aircraft Ice Prevention Methods
Ice formation on aircraft has long been a hazard to commercial and The military aviation, as well as the private flyer. Besides affecting the safety and performance of aircraft, severe icing conditions have been the cause of a large number of flight interruptions. Ice formation on the wings, tail surfaces, and fuselage is responsible for an increase in weight and the loss of aerodynamic efficiency. Severe vibrations and loss in thrust may result from ice accumulation. During heavy ice conditions in which ice occurs on the propellers and the aircraft simultaneously, the plane may be unable to climb properly, or maintain altitude, causing an emergency landing. The issue of determining adequate and practical means of combating ice formation has brought deicing and anti-icing systems to the forefront in aircraft design. This blog will focus on bleed air technology, pitot tube heating, propeller ice prevention, and heated edges systems.
Most transport-category aircraft heat the leading edges of the wings from the inside by bleed air siphoned from their turbine engines, and then piped to the appropriate location. The airfoils are heated before the aircraft encounters ice, to prevent unwanted accumulation. One drawback to bleed-air heating of the leading edge is the power it draws, which can limit aircraft performance, such as at takeoff. As long as the engine is running, bleed air from the turbine section will be hot enough to prevent ice from forming.
Ice adhering to pitot tubes exposed to the slipstream and water-laden atmosphere are just as susceptible to icing as airfoils. Pitot tubes, stall vanes and outside air temperature gauges can, in an era of glass-cockpit aircraft carrying extremely sophisticated sensors, quickly become useless or error-prone should they become encased in ice. On sophisticated aircraft, these tubes are usually electrically heated, often automatically before encountering ice. On a Cessna 172 or a Piper Archer, for example, a heated pitot tube is pretty much standard equipment, except the pilot must remember to turn it on before encountering icing conditions.
Because propellers are airfoils, they too must be protected from ice accumulation lest they lose their ability to produce thrust. Modern aircraft use electrical power to prevent or shed ice attempting to adhere to the blades. In earlier days, propellers were often protected by a system that squirted alcohol on the blades to shed ice. Piston engines demand a free flow of air to operate, a flow that icing can disturb. Piston aircraft will normally offer the pilot an alternate air-source option to suck air from a location out of the slipstream in the event of an icing encounter. Turbine engines have no love for ice either or are usually protected by electrically heated inlets that must be switched on before the ice begins forming.
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