Light Aircraft and Icing
The DA42 recently received its FIKI certification from FAA. FIKI ? Flight Into Known Icing conditions. Happy owners of DA42 equipped with the TKS system can now legally fly in clouds at temperatures below zero. Legally. But would that be a sound decision ?
Ice impact on performance is really strong. My experience of icing is very limited, as all light single engine planes I flew were not certified for flight in know incing conditions, so any ice encounter was unexpected, and quick escape was needed. If none was available, the only way would have been… down.
Jets and turboprops have much better anti-ice and de-ice systems, because their engines have all the extra.power required to melt the ice down, using hot air from the turbines, or pneumatic boots driven by the turbine compressor.
But the sole way to avoid icing problems is to not stay in icing layers. This is exactly what larger planes do. Icing can occur in any cloud when the temperature is below zero degrees Celsius. But if the temperature falls below -15, icing usually stops, except in Cumulonimbus. Jets simply climb high enough to be out of the icing layers.
Why don’t small planes do the same ? Because this requires much power, and the “ice-free” altitudes require turbo-engines and pressurization, or at least oxygen systems. The DA42 has turbo engines, but no pressurization nor oxygen…
I saw once ice forming on the leading edge of an Airbus 320, from Geneva to Zurich. Because this is a relatively short flight, we were flying at 15′000 feet only, the perfect altitude for icing. After a couple of minutes, the layer was so thick that the crew descended a few thousand feet to get out of it.
When I asked the Captain while un-boarding the plane, he confirmed that he descended because of ice, and that both anti-ice and de-ice systems were both running. Conclusion ? Even a plane with two powerful jet engines can’t sustain severe icing for long. So what about a DA42 with TKS ?
Only time will tell…
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Category: Modern Aviation
Tags: DA42 Diamond FIKI icing
