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its icy grip. This was the reason for the lack of rotation; the bearing was fine.
I had – and still have – a question that has never been satisfactorily answered. PT6 engines have two drains, forward and aft, at the bottom of the compressor case. These are designed to spring open when the pressure equalizes on both sides of the drain but they close when the compressor’s rotation creates higher internal pressure, to avoid an undesirable P3 leak. Their primary purpose is to provide an exit path for fuel following a no light-off starting attempt. Why didn’t they permit the water to drain from the case in this situation? Were they installed incorrectly? Were they defective? Or did the ice freeze over them rapidly enough that they became plugged before much water could exit? I don’t think we will ever know the exact reason, but we do know that this incident did indeed happen and led to unnecessary delay and expense.
Bottom line? Do not use a simple bungee cord setup under these conditions. Cover up those exhaust stubs with the propeller restraint when it’s rainy and cold.
My last comment has to do with storing the restraints when not in use. There may be room in a wing locker – if you have them – to simply toss them into the locker along with the pitot tube covers, engine intake plugs and heat exchanger inlet plugs. But if no locker is available or if it
is full with baggage, golf clubs or skis, now is the time to fit all of the items into the small canvas bag that Beech provides with the new airplane. That can be a tight fit.
What I have found that works well is to insert one exhaust cover into the other one then roll the combination down the elastic straps until they’re three inches or so away from the sleeve. Now insert the wad of covers and straps into the sleeve. Voila! A rather compact package easy to stow and easy to unroll to use the next time. There are probably other methods that work just as well or even better, but I like this one.
The good of the restraints? They protect the RGB from possible damage. The bad? They are difficult to install until the exhaust stacks cool. The ugly? When you start the engine with them still installed, you’ll need to buy a new set – not to mention the ridicule you will receive from the line people and other pilots! 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.
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26 • KING AIR MAGAZINE
SEPTEMBER 2024