Basically all the TPE's come with 3 turbine discs. 1st, 2nd and 3rd stage. Predictably, the 1st stage which is closest in line after the burner, is the one that gets beat up the most. Makes sense, since it gets all those hot gases on it. This eventually cause heat exhaustion and erosion. Predictably, Honeywell charges the most for the 1st stage. I don't have a cost for it, but it's probably in the $20K range. 2nd stage I think is $14K new and the 3rd stage is only $7K our something. They all have cycle times. Each wheel's cycle when new pretty much equals the TBO time. So a 1st stage turbine will have 5400 cycles on it when new. Now, what some do, as they probably did on mine, is they might replace with a used disc that has been yellow tagged. So, rather than spend the money on a new disc, they bought a used one with cycles left on it and put that in. Either that or they flew a lot of really short runs and used up more cycles than hours. My hot section is only due in 400hrs or so, but the left engine 2nd stage will cycle out in about 130 cycles. Now, that could be 400hrs if you fly longer trips a lot, but if you fly shorter ones, then those 130 cycles could be used up quicker. Depends on the flying you do.
As for phase inspections, which is just a fancy word for an annual, they come in a few different flavors:
1. One you subscribe to..
2. The manufacturers..
..or...
3. One you get approved yourself.
It used to be on a part 135 cert and they followed an approves MP that had 150hrs. I didn't want to follow that and pay for it, so mine has reverted back to the manufacturers, which is every 100hrs (I think on the later models, the factory one is 150 hrs). Good thing about that is that if I don't fly a lot, I won't have to do an annual every year, just until the 100hrs are up. Bad thing is if you do fly a lot, you need to do an "annual" maybe more than once a year. That said, they're not anymore expensive or time consuming than an annual on a piston twin. And you can submit your own inspection program and interval to the FSDO and have that approved if you want to. And Glenn, with a faster plane, you'll fly less hours per year. If you flew 400hrs in a piston, you'll probably fly less than 300hrs in turbine as you get there so much faster. So the inspection hours are "worth" more.
As for availability of engines, you're unfortunately up against all the crop dusters who suck up used TPE's like there's no tomorrow. They love them as they can run them up to 9000hrs. Dash 1's are easier to find than Dash 5-254K's, that's for sure. Not plentiful, but they're around. In fact Morris just called and said he had a set of Dash 1's he'd found. 254K's you never see. 251's are perhaps a little more common. Dash 10's are not used as much in crop dusting, but on the other hand, very few used ones are available. So, from an availability standpoint, the Dash 1's and the Dash 5-251's (690A/B's) are probably the easiest to find. 254K's (840's, 900's) are unobtanium. Dash 10 availability used I don't know enough about, but I would guess not great.
