Perhaps DAR could try this ,feathering a PT-6 on a `Caravan....?
I've feathered the PT-6 on Caravan, DHC-6, and DC-3T. It works fine, and the engine runs happily at idle while the prop luffs at only a couple of RPM. However, great care is required bringing it out of feather, as it is easy to surge and overspeed. Handled gently, it's fine, but too quick hands will be expensive and damaging. The Caravan glides very much better prop feathered - like a push from behind as it goes in to feather!