Page 28 - November 2022

Only in the 300-series – with their splendid performance and their pitot-cowls – is the title of the appropriate procedure “No Starter-Assisted Airstart (propeller feathered or windmilling).” For the other models, the title is “No Starter- Assisted Airstart (windmilling engine and propeller).” Getting the “encouraged” 10% N1 or more before introducing fuel is easy with a windmilling propeller but much more difficult with a feathered propeller. The windmilling airstart envelop for all King Air models is a minimum of 140 KIAS and below 20,000 feet. Of course, the higher the speed and the lower the altitude (within reason!), the more N1 speed we will obtain. Hence, diving at high speed down below 10,000 feet can yield just as much compressor speed with a feathered propeller than having, say, 150 KIAS at 17,000 feet with a windmilling propeller.
Folks, let’s be realistic here. Are you going to actually do this? Do an
airstart with a feathered propeller? I bet not. First, how many times would you choose to restart an engine that you decided to shut down in flight, other than during a training session? Second, if the propeller had been feathered – as it almost certainly would have been when completing the shutdown procedure – why wouldn’t you just go ahead and use the starter? Third, only if the starter chose this particular time to become inoperative would there be any need for a windmilling airstart with a feathered propeller!
Even during flight training this is not a very desirable procedure to practice or demonstrate. Why? Because although the peak ITT will likely be well below the starting limit, it will be quite a bit higher than you are used to seeing. Why subject your hot section to that higher temperature?
So, for me, I prefer to always have a propeller windmilling at
takeoff RPM while conducting a windmilling airstart, since it leads to very comfortable starting ITTs.
Now I’ll let you in on a little secret. Remember those Raisbeck- Hartzell propellers that rotate about 20 RPM when feathered? Or, even another propeller that happens to have its feather blade angle set such that it rotates in the forward direction? Well, move the propeller lever from feather to the full forward position and lower the nose to pick up some extra airspeed. See what is happening? The propeller is unfeathering itself! (You remembered to turn off the Autofeather switch as part of the inoperative engine cleanup procedure, didn’t you?)
No King Air has ever been built with unfeathering accumulators, a popular option on some piston twins, especially ones used for multi-engine training. Without that type of device, the only way in
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26 • KING AIR MAGAZINE
NOVEMBER 2022