AirRider

Hi all, my company is looking to buy a Turboprop and fly 91. One specifically we are looking at has us curious. I don't have much turbine experience. The engines are 400 hours over TBO and I was wondering what your thoughts were on the impact of the engines already being over TBO.

Does that drastically alter the price?

I can't find a record of reliability online about flying turbines (PT6A-28) past the TBO, what are your thoughts as far as safety and reliability?

Is it common for insurance to cover overhauls or hot sections?

Thanks all.

fjetter

You may get more/better responses if you move this thread to the 'Corporate' section....the guys there probably have more experience dealing with those issues....

Just my $.02.....Good luck!

periksmoen

I wouldn't let the fact that it is over TBO scare you. While the value of a 4000 hour engine is certainly going to be less than that of a 3000 hour engine, the value doesn't automatically plummet when it goes from 3,599 hours to 3,600. As long as the engine has been properly cared for, it will still have lots of life left in it for a part 91 operator.

I have several thousand hours behind PT6's that were beyond TBO (some with well over 10,000SOH) and have never had an in-flight failure. With proper care and active trend monitoring, you should have no problem getting plenty of life out of that engine.

I don't believe there is any insurance policy that will pay out if your engine suddenly needs an overhaul or reaches a life-limit (unless, of course, the airplane just 'happened' to catch fire the day after finding out that it needed a major overhaul).

dustrpilot

I flew behind a -28 in a spray plane that was way past TBO. Never a problem at all with it. If the hot section passed and you could establish a good maintenance history on it, I'd fly it like I stole it.

dtoTUL

For Part 91 operation, you're fine going over TBO. Like the others said, the PT-6 is a solid engine and will not likely come apart. What you will see is deterioration in performance. The danger here is your climb performance on hot days - especially at high elevations. When dealing with a potential purchase, you should definitely take into consideration the fact that it's over TBO when making an offer, but don't necessarily let that kill your deal.

It would be a good idea to plan on having a Hot Section done in the near future if you do go through with the deal. But at minimum, have a reputable shop do a borescope inspection on it and they can give you an idea of what kind of engine you're getting. (if you're near Oklahoma, I'd recommend Covington Aircraft in Okmulgee, OK)

Another thing to look into is the MORE program for PT-6's. I used to maintain a King Air with -20's that were nearly 8000 SOH. But they were on this program that basically tracks the life of the engine through more frequent inspections and regular trends. The program is mostly for 135 operators, though, I believe.

N9373M

I don't know squat about engines compared to the answers you've already gotten, but one rule of thumb in the piston world is that the engine has to be used regularly. Don't know if that xfers to the turbine world, but I thought I'd throw that in just in case.

CaptainTeezy

I am in a similar situation, so I asked a similar question in the corporate section like someone suggested. But it seems as if all the info is coming here. But I will ask the question here....What is the average life span of a PT6???

falcon20pilot

I responded in the corporate section, but 7 to 8,000 is not unreasonable to expect when maintained properly. Getting the bore scope done is important so you know what you are starting with and know the previous owner was not constantly over-temping the engines. The MORE program sets out maintenance procedures that make the engine actually certified for part 135 to as much as 8,000 hours. Don't spend the money on the actual STC for MORE, but research it and maintain your engines the same way and you should have good results. Just as an example every 400 hours some of the things that are done include changing fuel nozzels, compressor wash, re-calibrating all the engine gages, propeller balance and vibration analysis, and oil analysis. Track your engine parameters each flight to monitor trends, mostly for the health of the hot section. The rest of the engine is pretty bullet proof - the only compressor or power section failures I have seen were due to FOD.

thomasw

While I agree the PT-6 is a very robust engine and as long as the maintenance history and hot-section checks out OK, you "should" be fine to operate the engine for many more hours to come.

Now that said. .I've got nearly 2000 hours behind PT6's ranging from 20's to 42's and every actual engine failure i have had, has been a PT-6 shedding the power turbine disk. One of these was in a KA-200 immediately after rotation, and the 2nd was a PT6A-20 during climb out.

So while the engines are built like tanks, and nearly indestructible, they do fail.

falcon20pilot

Thomas were the failures attributable to FOD and if not was the cause known after tear down? And are you sure it was the power turbine and not the compressor turbine? The only failure I have had in managing over 25,000 hours on 90 series King Airs has been the compressor turbine disk, and both times technically due to FOD. Not saying we have not worked on power sections, but we caught those due to strange noises in the reduction gear box or power section prior to catastrophic failure.