Panama Jack, and any others interested, I suggest you look at some other threads on PPRuNe.
First look at “Van has engine failure in Tanzania” in the African Aviation forum. In particular look at Shenzi Rubani’s post in that thread on 21 October 2004. Eight Caravans going down in a one year span because of engine failure indicates that the PT6 is not as reliable as P&WC and some operators would have us believe. You will note that the aircraft belonged to different operators in different countries so blame cannot be attached to one outfit’s operating procedures or maintenance standards. The only common factor is the PT6. You might also look at the thread earlier this year entitled “Van down in Tanz”. In addition to the Caravans, there have been other single turbine engined aircraft, such as the PC12 you mentioned, going down in the same time frame because of engine failure. In the face of this evidence in only single engined aircraft it is difficult to see how Pilatus can claim that PT6 powerplant failures are pretty much unheard of!
If you have only one engine, when it all goes quiet at the front it does not matter what fuel that engine was using. You are still going down and are dependant on there being a suitable landing site within gliding range and on the pilot’s skill to get you safely on to that site! This assumes the pilot is able to see the landing site, which is most unlikely at night or in serious IMC. As Shenzi Rubani mentions, there have been engine failures in King Airs, etc in the same time frame but they do not show up in the accident statistics because the second engine enabled their pilots to get them safely back to a proper airfield.
To give credit where it is due, the PT6 is a wonderfully reliable engine. However, it is not infallible and its failure rate is high enough to be of serious concern for single engined passenger carrying use, such that single turbine (as well as piston) engined aircraft should not be permitted to carry fare paying passengers in IMC, at night or over water or inhospitable terrain. I see no problem with the use of single turbine engined aircraft by freight or private operators, whose pilots and occupants presumably know of and accept the additional risk. Similarly, I have not heard anything negative on either the PC12 or the Caravan. Both seem to be great aircraft that do an honest job. There has been some mention of airframe icing on Caravans but I suspect this is due to Caravans being regularly used in some pretty harsh climates. Any other type of aircraft used regularly in such climates will also suffer icing more often than if used in a mild climate. The only problem I have with both aircraft is that they have only one engine, which to me indicates that their operations when carrying the paying public should be limited as outlined above.
Second, look at the thread earlier this year on the Canada forum regarding Bearskin Airlines and the PC12. Some years ago Bearskin introduced some PC12s to replace some of their King Airs and similar aircraft. Now it seems they have been getting rid of the PC12s. There must be a reason. Perhaps it would be worth your while to contact Bearskin management or pilots, perhaps initially via a post on the Canada forum, to find out why this change is happening. If you find out by means other than PPRuNe, please post it on PPRuNe. I have also been wondering why this change is taking place at Bearskin.
Hope the above helps.