Page 28 - June 2023

ASK THE EXPERT
Ice Vanes: How Important Are They?
by Tom Clements
One of the ongoing debates among King Air pilots has to do with the necessity to use the engine anti- ice system as the Pilot’s Operating Handbook (POH) directs: “Before visible moisture is encountered at +5°C and below, or at night when freedom from visible moisture is not assured at +5°C and below.”
Depending upon your exact King Air model and the cowling modifications it may contain, power and airspeed always take a hit when the ice vanes are deployed. The speed loss may range from five knots to as much as 15 knots. It is this performance degradation that makes many pilots reluctant to pull the handles or flip the switches for ice protection.
The other factor that influences a pilot’s decision about ice vane usage is the experience and beliefs of other pilots with whom he or she associates. When the crusty old gray-beard that has been flying these airplanes for thousands of hours believes that ice vane usage is not very important, it is hard for the newbie to go by the book. In addition, when it is so frigidly cold outside that the water content in the air is already well-frozen, such that no ice adheres anywhere on the airframe, it is an easy leap of faith to conclude the engines are also not going to be harmed by ice.
I strongly disagree with the casual approach to ice vane usage and plead with you to indeed go by the POH’s directions. Let me explain why.
Depending on your piloting experience – specifically, how much time you have spent flying in clouds – I will wager that you have experienced a variety of icing events. Although the OAT may be the same from one event to another, the outcome can, and does, vary greatly.
Whereas last week’s icing encounter really got your attention as the windshield heat barely kept up with the demand, this week the airframe came through without a trace. Go figure!
In support of those pilots who have a casual approach to engine anti-ice usage, perhaps they are the luckier ones and have had the great preponderance of their icing encounters be non-events. Hey, I can relate! Especially when we are up there in the high 20s or low 30s (thousands of feet) and the airframe is staying ice-free; it surely seems logical – but incorrect – that the engines will also be safe.
I am going to share two separate scenarios that happened to individuals that told their stories directly to me. My hope is to make you “scared straight” so that you will embrace the POH’s conservative approach to ice vane usage.
The first story involves an old friend of mine with whom I have conducted initial and recurrent King Air training since the 1970s. When I first met this fellow, he was flying a B90 and the various companies he advanced with moved up the King Air ladder so that he was checked out in just about the entire King Air lineup by the time he retired. Although he never argued forcefully with me about ice vane usage, being a kind, southern gentleman, I know that he was reluctant to deploy the vanes unless the airframe was collecting significant ice. Nothing I taught could convince him that he was playing a dangerous game.
26 • KING AIR MAGAZINE
JUNE 2023