From: Victoria, Australia
I had noticed that turboprops always feathered the props on shutdown, but piston engine planes didn't. I finally figured out why. The wind will cause a turbo prop to windmill if not feathered because there is very little resistance on the shaft when unpowered. On a piston engine, the wind is trying to move the pistons when shut down which means there is a lot of resistance, so they are not feathered.
As far as I've noticed, the pitch on shutdown for a piston engine is usually whatever the pitch was before shutdown, which is, I believe, usually fine pitch when taxiing.
I'm just speculating though. I've never really heard the answer from a pilot.
The ATR (perhaps the Dash-8 and others as well) will normally shut-down with the props feathered. All of the turboprops I am familiar with will shut-down with the props at a flat pitch though. Residual oil pressure will drive the props flat during shut-down so that the props can "sit" on a prop-lock. The flat pitch reduces drag during engine start. I'm not sure a turboprop can even be started on the ground with the props feathered (never tried). The ATR is a different beast though. I'm not Typed in the ATR but I have heard that the props are not directly tied to the turbine (via a reduction gear assembly) as other turbo-props are. Rather, the ATR's props are tied to a separate shaft and turbine (think tube within a tube) allowing engine start independent of prop rotation. Check out www.airliners.net; cool site.
The Lockheed Electra/Orion is the exact opposite....
(One day I will learn to spell - or check before posting....)
Uh oh, Firefox has a spell checker!! What excuse can I use now!!!