Page 22 - Volume 11 Number 3

Ask the Expert Ice Vanes:
How Important Are They?
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.
by Tom Clements
“I strongly disagree with the casual approach to ice vane usage and plead with you to indeed go by the POH’s directions.”
20 • KING AIR MAGAZINE
MARCH 2017