Having spent nearly an hour with the intake of a PT6 so iced up that you couldn't have put your fist in the hole, and the engine not missing a beat, I think that the power unit is the least of problems with this aircraft. Get it near water or ice, and it's bad news.
On one flight, so much water dripped into the electrics that I spent 30 mins with stick shaker and buzzer running. No big deal, but in blackness, moderate turbulence and lashing rain, I wondered what was going on for a moment or two.
On another flight I had rather a memorable 40 mins with frozen elevator and elevator trim. Nothing...totally locked solid. After five house of maintenance I carried my luckless passengers to JSY, at night in a blizzard, only to find that I couldn't reduce the power on one engine due to the same kind of problem. Iced up control runs.
I think the Shed, or Skip as some of my passengers called it, is only suitable for fair weather ops.. Or perhaps a museum.