It would be interesting to gather some real world understanding of privately operated SET. My experience has only been in corporate, but my impression is that in looking at turboprop vs piston some issues need consideration.
Am sticking to the venerable PT6, which as a free turbine has less potential issues to consider.
1. Paranoia about a hot start. Less of an issue with a PT6 as long as you are diligent on protecting the battery. I used to disconnect the battery when shutting down for the day. Ensuring you motor the start when the turbine is hot. Not sure how critical it is to be facing upwind on a strong wind day, but probably a sensible precaution. Understanding hung start actions. Not sure what a hot start will cost in terms of maintenance but probably a multiple of a piston overhaul?
2. Maintenance cycles and timed items. Some operators still use a Cessna 421 over a turboprop because their business model is low annual hours (say less than 200 hours pa). Am not sure how much one can generalise, but turboprops will have more calendar timed component inspections, and start sequences might also count towards engine maintenance programs. While a burger run in a Cessna 421 is unlikely, might be even less so in a turboprop?
3. FOD risk, again the PT6 has some design features to minimise this, but a few of the SET are limited to tarmac runways in the POH. A not atypical incident is, muppet alert, an operator trying to light a turbine with the cowl inlet cushions still inserted? Not strictly FOD, more an issue related to 1. above.
4. Other component risks, eg the FCU. If for some reason you are AOG away from your service centre, how easy is it to get the aircraft serviceable and returned to service?
There are some incredibly capable aircraft that seem to be quite cheap, relatively speaking, but they come with a host of new operational considerations. The MU2 with shaft turboprop engines and 300 KTAS might be found with reasonable timed components for $500k, but the step up in type knowledge and competency, let alone as a single pilot operation, is huge.
MU2 in Europe seems like a pipe dream. in contrast to the US, they are super rare over here. How/where will you do maintenance?
And potentially noise issues with the MU2, too?
HBadger wrote:
MU2 in Europe seems like a pipe dream. in contrast to the US
I looked into the MU2 many years ago. A very interesting design. It performs very good at rather low level, it can land on short unimproved runways etc.
But the airframes and especially the systems are 40 to 50 years old. The cockpit looks like an ergonomic mess. You end up with an autopilot from the stone age whith few options to upgrade etc. It consumes quite a bit of fuel and finally it is over 4 tons which drives any fees through the roof here in Europe.
A perfect plane for somebody with specific shipping requirements. Cheap to buy in case you need another one, fast, can fly long range at low altitude, can land in a backyard, can haul a big load. For the rest of us better forget it.
But the flap configuration is interesting and I lately saw that the latest TBM seems to have copied to some extend the MU2 spoiler design to increase performance.
Isn’t MU2 a twin engine turboprop, and therefore per definition not a SET?
Other than that a very interesting topic. In my dreams I’ll step up some day and haven’t come to understand where the “frontier” is between high performance pistons and “low performance” SETs.
In particular, maintenance-wise one could do maintenance of a SET in pilot/owner regime, but not twin turboprop. I could imagine that maintenance of a turbine is even less work than of a piston powered one, because there is so few to check. For example, maintenance of a Piper Jetprop could be easier than of a Malibu. Couldn’t it be that yearly costs of a Turboprop could equal out with a piston plane, e.g. when maintenance is done with owner participation? Taking into account that turbines can be run 4000 hours and more, this could be particularly interesting.
RobertL18C wrote:
It would be interesting to gather some real world understanding of privately operated SET.
Some useful info on this thread as it relates to the Jetprop.
https://www.euroga.org/forums/aircraft/3504-jetprop-grass-strip-short-field-performance-porn
The JP is possibly the most accessible SET for a GA pilot.
With 3.5 years experience between a TBM700 and now the JP I can say that I have never had a problem with hot starts, not even close. Of course, I always leave minimum 15 or 20 minutes between shut down and restart, and in that case would motor the engine to get the tempo down before ignition.
Buckerfan wrote:
The JP is possibly the most accessible SET for a GA pilot.
I would add the Silver Eagle (C210 Allison conversion) to that too.
These two are the only serious turboprops which can operate below 1999 kg and therefore are suitable for IFR without airway ripp off in Europe.
RobertL18C wrote:
Paranoia about a hot start.
Exactly that, paranoia. Happens much rarer than people think but is expensive when it does. Keep to the book and it most likely won’t.
Sebastian_G wrote:
finally it is over 4 tons which drives any fees through the roof here in Europe.
The 1999 kg limit has killed lots of airplanes in Europe as nobody wishes to pay the Eurocontrol taxes. Practically all twins over 2 tons and below the business twins like King Airs e.t.c. are non-sellers these days here. It may in many cases be a case of penny wise/pound foolish, where the taxes are not the worst cost factors but are thought to be.
The MU2 is a great airplane but it is, and unfortunately has proven this many times, NOT a plane for occasional pilots but for people who fly it a lot to keep proficient. Its design has bit a great lot of folks and therefore it is also one of those airframes very difficult to get insurance for as a private operator.
UdoR wrote:
Couldn’t it be that yearly costs of a Turboprop could equal out with a piston plane, e.g. when maintenance is done with owner participation?
We owned a PA46 piston and trubine. Maintenance cost has been very similar, the turbine is probably even less. The turbine could turn bad which is very unlikely but then very expensive. But also with other airframe you could have unlikely but very bad things happen like main spar corrosion, main spar delamination etc.
But most of the time turbines will be fitted to bigger planes with more systems so maintenance will be more expensive, but that is not due to the powertrain.
RobertL18C wrote:
Paranoia about a hot start
It is not only a hot start unfortunately as most turbines we have today in pre owned planes have little protection against a user which exceeds parameters. You can overtorque and overtemp the engine. If you follow the procedures it does not happen and not even comes close but it needs a little attention. But there are a few easy mistakes which can end badly. The closest I have ever seen a PT6 come to a hot start was when the pilot flying forgot the igniters due to time pressure etc. Not an issue but then fuel was introduced, ITT did not rise?? the pilot did search for the issue and I kind of yelled “fuel cut off”. If at this moment if you figure out you forgot the igniters, turn them on and all the pooled fuel in the combustion chamber will burn at once and drive the temperature beyond all limits without a possibility to stop it as the fuel is already in the engine. A piston engine could be destoyed likewise by closing a wate gate completely on the ground with full power etc. but most designers managed to provide a little better protection. In 20 years this will be a thing of the past with digital turbine management in wider use.
RobertL18C wrote:
2. Maintenance cycles and timed items.
Nearly all components of the PT6 seen to run on hours and cycles only. Nothing major is on calendar time
RobertL18C wrote:
start sequences might also count towards engine maintenance programs.
Most private operators do not have cycle logs so 1h is assumed to be one cycle. But cycle limits on the engine are around 20k cycles so for private use do not matter. Also private owner tend not to be on engine programms (for turboprops, jets are different). Those programms make little sense if your overhaul is 20 years away and you might fly less than the annual minimum of the programm. Personally I would not trust any programm I pay several 100k to actually overhaul my engine in decades. I saw too many restaurants with signs “sorry we are under new ownership, old voucher are unfortunately invalid now”.
RobertL18C wrote:
While a burger run in a Cessna 421 is unlikely, might be even less so in a turboprop?
You will burn a lot of fuel in comparision to a piston. For a few such flights every year it does not matter in the big picture but if you do such flights mostly it is not very efficient. In the turbine you will try to minimize the amount of starts though so if we do pattern training we fly to places nearby where we can pay online so we do not have to shut down just to pay a landing fee.
RobertL18C wrote:
how easy is it to get the aircraft serviceable and returned to service?
I would say this is very similar for all more compley aircraft. In a C152 you will most likely find some expert at any place you travel to while in bigger aircraft it will be more difficult. But I think there is no major difference between piston and turbine.
RobertL18C wrote:
There are some incredibly capable aircraft that seem to be quite cheap, relatively speaking, but they come with a host of new operational considerations.
I think this usually does not work out. Better spend some more and then spend less maintaining this aircraft. Older piston twins are the prime examples. You buy them cheap but then pay a fortune to run them and then resell them even cheaper. Better get a little more expensive plane which just flies.
As I often write, maintenance cost is very related to your exact situation. Whether you use a company or a freelancer is a factor of two right away. Here are some old threads.
Somebody quickly points out that while you can “maintain” a piston at some monkey outfit, if you maintain a TP that way, the resale value will be crap, so almost nobody does it. But that’s a different discussion 
The mission profile is also different versus pistons. Not just low level fuel burn but stuff like not being able to get decent photos out of the windows of a pressurised hull. I could buy a Jetprop tomorrow (indeed it is far and away the best direct upgrade from a TB20) but
So I won’t get one. I am tired of the hassle caused by relying on other people who bodge stuff half the time, tired of the GA paper collection pipeline, tired of the UK CAA/NATS ex-RAF pensioners trying to f**k a GA pilot for 5 seconds in CAS, know too many owners who have months of downtime, and I want to optimise my enjoyment of GA.
15 years ago I nearly bought a hangar, but a crooked estate agent conned me. That would have changed everything.
BTW, the European IFR route charges are not a big deal if you actually use the plane for real. The landing fees will cost you more. But King Airs tend to have a different mission profile where none of this matters.
Mooney_Driver wrote:
Exactly that, paranoia. Happens much rarer than people think but is expensive when it does. Keep to the book and it most likely won’t.
The same goes for gear up landings or similar f***-ups. But for these one buys insurance. Is there such a thing as hot start insurence? Happens almost never but when it does it’s expensive sounds exactly like something that one should get insurance for.
@Sebastian_G really appreciate the response. I had forgotten the gotchas you mentioned (haven’t flown a turbine in a few years), but recall the switchover from monitoring MCT to max ITT. Single crew and in busy ATC it is not impossible to miss the crossover and bust a limitation. In shutdown it was always a nice relief when the event recorder had nothing to report :)
There is a cult of the MU-2 stateside, where the FAA mandatory recurring crew training requirements has made it the safest turboprop. The systems are so well built and designed for long life, that these fifty year airframes have an excellent reputation for reliability. Conversely, pilot ergonomics are somewhat 1960’s fighter pilot analogue dials (with a nod to the Starfighter style undercarriage design), with ancient autopilot which is an IFR MEL item. The loyal owners are hoping that Garmin is about to provide a modern autopilot STC for the type. A well maintained short body for $500k delivering 300 KTAS and NBAA 1000 NM IFR range ensures they have a loyal following. Support from Mitsubishi is supposed to be first class.
