NASA,
I think you are drawing the wrong conclusions suggesting that turbines are not cost effective.
Your clients have experienced some appalling overhaul bills that may be attributed, not to the fact they these engines are turbines, but to the way they have been abused. My organization has operated turbine aircraft PT-6, TPE-331 and JT-15 equipped for the past twenty odd years. Although we have occasionally smarted when reviewing HSI or overhaul accounts we have not experienced anything like you describe.
Our -41/42 engines had over 17,000 hours each when we disposed of the aircraft and the last overhauls were still cost effective. Two recent -114 overhauls were under $USD 135K and 130K respectively. The HSI on both those engines required no engine shop visit and were completed in a day at the hangar. Two -60A's were overhauled at 5000 hours and at a cost of $USD186,000 and $USD165,000 each. The HSI's on those two engines carried out at 3,500 hours were around $35,000 each.
Turbine engines such as the PT6 variety probably cost about $USD 1million each. Any operator faced with the bills you suggest should look very carefully at his maintenance procedures, operating procedures, check and training and crewing. Pilots should be well disciplined, experienced and hold the operators interests (and their jobs) to heart. ‘Second place' operators should leave the industry and try farming.
And:
[quote] "just as a matter of interest, when does a new aircraft from the factory, become a used aircraft, which in your opinion, we should all steer clear of?????"<hr></blockquote>
That is a matter for the buyer. New aircraft come with factory warranties and the option to participate in maintenance service plans. Such options provide the operator with firm DOC's. A used aircraft with a partial warranty may be an option if the buyer wishes to take immediate delivery and enjoy factory support. An older aircraft may provide a cost effective alternative if the pre-purchase inspections reveal all the good and bad points and the price is negotiated accordingly. Of the past four aircraft we purchased, three were new and one was low time used. A HSI was completed as a pre-purchase agreement at the sellers expense!
A properly maintained and serviced turbine aircraft should have a life-span of ten to fifteen years and at least recover somewhere near the initial purchase price at resale.