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Beechcraft Super King Air 350 (N495DH)
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Beechcraft Super King Air 350 (N495DH)



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Can someone with more knowledge than I have explain the reason for feathering the props like this? I understand not wanting them to windmill from and sudden gusts or steady winds, but won't they still paddle wheel in gusts from the side?
sam kuminecz
When on the ground many turboprops are in this position, when at a certain rpm they rotate. When the aircraft is not moving for a while there are hooks that attach to the exhaust from sleeves on the prop tips to keep from windmilling
Here's an image that explains how the props are tied down after flight and what Sam was talking about.


The main reasons for this is so they don't rotate all night long with dry bearings.

As for feathering at shutdown. These are P&W PT-6 engines which are a free-turbine, reverse-flow design. Simply put, the air enters at the intake under the spinner and flows to the rear of the engine, then it enters the engine itself and flows forward through the compressor section, into the burners and then through the turbine section and out the exhaust near the front. The turbine section, up front with the prop, is driven by the compressor section by aerodynamics alone, no direct shaft input.

The props are normally feathered before shutdown with the prop lever, although the loss of engine oil pressure on shutdown will feather them automatically, but this is not the recommended procedure.

Now Garrett TPE 331 engines are a different design and are not feathered on shutdown. They remain in a flat pitch condition. Sorry, I don't know much about them.

A very nice photo with great light at Jackson WY.
Roy Hunte
Interesting info, Jim, the Cessna Caravan uses the same type of engine, and a similar tie down rig.
Bernie, they feather because they have lost oil pressure. In an engine failure you'll lose your accessory gearbox attached to the back of the PT6 and with it your oil pump. Oil pressure moves the props to fine pitch. No oil pressure, no pitch!
Great pic by the way!
Daniel Purdo
Understand it was cold when picture taken. Nice shot!!
Nice airplane!! Tripod recomended!!


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