Continuing with the theme of thunderstorms and the risk they pose to aircraft of all types, I have chosen a system that combats severe thunderstorms as well as other hazardous weather. Specifically, I would like to focus on de-icing, which can be thought of as a risk-mitigating subsystem as part of the flight controls. As we know all parts of the aircraft system are important, some more than others. One of those that may top the list of importance is the flight controls. They must be near perfect for the aircraft to perform optimally. One tool that most aircraft utilize to help maintain that optimum performance during severe weather is de-icing. Icing occurs during severe thunderstorms and snow conditions. I remember my instructor once told me, the formation of ice on a wing the thickness of sandpaper can reduce lift by up to thirty percent. This illustrates the importance of combating such a risk at all costs. To prevent icing from occurring and mitigating the risk, aircraft have built-in or attached de-icing systems.
Before going into the preventive methods, let's discuss what icing is. Icing is a cumulation of water on flight surfaces that freezes over and becomes detrimental to flight. There are two types of icing, clear and rime. Clear ice is caused by larger sized water droplets that are left by rain or melting snow. Once the water makes contact with the flight surface it trickles across it, causing a larger surface area to be engulfed in ice. As the name states, it is clear, making it hard to detect. It is also heavy and thus harder to remove. Rime ice, on the other hand, is caused by smaller droplets, that freeze instantly is lighter, and has a cloudy look to them, making it easier to detect and melt. It is more important to remove rime ice as it has a rougher, bumper surface that quickly degrades the aerodynamic abilities of the flight surface.
(Figure A)
There are multiple ways to mitigate the risk of icing, most involve either a heating element or a chemical one. Most deicing systems concentrate on parts of the airplane that are most susceptible to icing. These include the leading edges and windshields. To prevent icing on windshields, most have thermal electric elements throughout the glass and some have a special chemical spray that prevents icing from forming. For leading edges the options are plentiful. There are thermal pneumatic and thermal electric systems that thwart icing. The most common being Ice boots and Wing Anti-Ice systems that use bleed air from the engine. There are other systems like chemical anti-icing systems, also known as weeping wing system. These systems use tiny holes drilled into a titanium attachment that sprays out a glycolic based chemical that combats icing.
(figure B)
Icing is a problem in aviation and if a system is not automatically activated, not activating the system could be proven fatal. But as technology advances and different systems become common, aviators of all levels will have the ability to mitigate dangerous weather conditions that cause icing.
References:
Aviation Maintenance Technician Handbook - Airframe, volume 2. (2018). Retrieved from https://www.faa.gov/regulations_policies/handbooks_manuals/aircraft/media/amt_airframe_hb_vol_2.pdf
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