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If you decide to switch on the panels while taxiing, it’s a good idea to leave the mode selector in the “Off” position. There are two reasons for this. First, leaving the mode selector off means that the vent blower can also be left off. If it is running, all it does is blow cold air out the various vents. Second, the cabin temperature sensor that feeds information to the control board when in the “Auto” mode is, for almost all serial numbers, located in the cabin ceiling. It can get an erroneous indication that the cabin is warmer than it is due to its proximity to the heated panels.
The only way to really get a lot of heat energy into an early 200 is via the bleed air input, but of course the temperature of the bleed air depends upon the speed of the engines’ compressors. I certainly do not recommend taxiing around in the winter at high idle or even more N1 speed – since the aircraft wants to roll so fast – but, while stopped in a run-up area, selecting high idle will indeed contribute to better heating.
A commonly reported annoyance with the radiant heat panels is that, in use, the heat weakens the glue that is holding the panel to its Velcro strip, so one or more panels begin to sag down from the ceiling. That does not contribute to warm and fuzzy feelings in the passengers! Thank goodness it has been rare, but there are also some reported cases of a radiant heat panel catching on fire! As I wrote earlier, this system is kind of a joke!
One last bit of advice before I bring this article to a close: It is never desirable to turn off a powerful duct heater at the same time that airflow through the heater ceases. Not being blown downstream, the residual energy in the heater elements can cause excessive, localized temperatures to result. So never switch off a heater while the vent and/or aft blower is stopped. Instead, switch off the heater while ensuring the blowers remain on for at least 15 seconds more. This important step is actually stated in the 300 and 350 POHs, but it is the proper technique for all models with heating elements buried in the ductwork.
I hope this information helps you King Air aficionados stay nice and warm during your winter flying! KA
King Air expert Tom Clements has been flying and instructing in King Airs for over 50 years and is the author of “The King Air Book” and “The King Air Book II.” He is a Gold Seal CFI and has over 23,000 total hours with more than 15,000 in King Airs. For information on ordering his books, contact Tom direct at twcaz@msn.com. Tom is actively mentoring the instructors at King Air Academy in Phoenix.
If you have a question you’d like Tom to answer, please send it to Editor Kim Blonigen at editor@blonigen.net.
26 • KING AIR MAGAZINE
NOVEMBER 2023