Slight thread drift -

When a piston powered / certified aircraft is converted to a turbine, the redline moves down to the top of the green arc, correct?

What are the reasons behind this requirement?

Thanks - Phil

A little complex, but turbines have stricter more stringent requirements. In a piston, Vno to Vne, the yellow arc is smooth air only. There is insufficient protection of the air-frame in turbulence. Vmo/MMo in a turbine is a normal operating envelope, such that the plane at that speed can operate normally (as in Vno in a piston). If you fly into a cloud with moderate turbulence in a turbine at Vmo, you and your passengers might get bent, but the airframe won’t get bent. Fly into that same cloud in a piston in the yellow arc, and you are not guaranteed that you won’t start shedding parts.

So, the only reason is the use of a "turbine" engine? Not the type of aircraft (C172 vs. M600) duty cycle & operating environment.

I'm having this vision of a purpose-built small turbine as a drop-in replacement in the 200-300HP power range. If the HP vs. altitude curve matched the piston version, why would the redline need to move other than the engine is a "turbine" / that's the way the reg's are written?

What caused this crazy thought? I was at a flying club meeting. Engine overhauls were being discussed. IO-540 for the C182 is $75K + shipping, R/R & accessories. Considering that cost and what a PIA it is to start (even with an electronic mag) this isn't going to last much longer. There has to be a better way.

I know you're going to say, they don't scale down very well. I agree.
Think from a clean sheet of paper scale up POV.

I find the PMOPA forum almost worthless, because it's so inactive. The people I'm likely to get responses from are you and a few others already on THIS forum. I've commented to my wife that M-class owners don't seem as apt to nerd out on airplanes.

Facebook's Cessna 400/TTx group is also good for Conti related questions and issues.

This discussion has me counting dimes for a JetProp upgrade in the future.

a "micro-turbine" would be awesome, but so far no one has been able to pull that off. The small Rolls Royce turbines could work, maybe the RR300?

Probably not cheap!

Anyone know?

My guess would be $850k

You should definitely pay to join the PA46 forums if you are considering the airframe. No question. I ultimately decided on a Meridian over the Jetprop but there are many owners who love their jp.

I flew a 2006 Meridian for 4 years. Averaged just under $1,000 per hour, no capital costs. Insurance for me, 36 yo 1100 TT 500 retract averaged about $15k for $1M hull $2M/250K. Annuals and unexpected mx averaged about $35k/yr. But lumpy with one year less than $20 and one year over $50. No big scheduled events. Nose gear actuator failed, boot replacement, etc.

Maybe if you kept the plane for a decadeand averaged out expenses you could get under $750/hr but I can’t imagine how to get to $500/hr For about 100 hrs a year.

I have moved to a Citation 550. Fuel is obviously more but other costs are similar. No comparison on comfort and capability.

Cons of the 550 are reposition flights for Mx or other reasons if I can’t fly, insurance requires two pilots which is a big hassle. I spend a lot of time during the week at the plane so Mx management isn’t much different than the meridian. Probably easier considering a lot of people work on legacy citations and I only had Mx done at Midwest Malibus for the meridian.

If I compare the 550 at around $1M to a Pilatus or king air at $2.5M++ then the decision was pretty easy for me.

Someday I may want a newer airframe and the benefits that entails at a much higher capital cost but for now the 550 fits my mission.

Previous Meridian expenses, FWIW

Isn’t $27k more than Mike pays for the equivalent of an annual (not the same thing, yes) on his Citation? That seems crazy high.

Isn’t $27k more than Mike pays for the equivalent of an annual (not the same thing, yes) on his Citation? That seems crazy high.

That is my experience also. And speaking with other owners that is in line. I have heard of these unicorn $15k annuals but I would imagine there is definitely deferred Mx there. If you can do that and not get caught and sell off to the next guy then I guess that works in your favor but not how I managed the aircraft.

I would tell anyone looking to buy an out of warranty meridian (the only setp I have personal experience with) you need to hope for $25, expect $40, prepare for $50 and if you have a really bad day/yr $100k in Mx could be possible. In fact I saw another owners pratt (Vector) invoice for a hot start total $263k all in. So there’s also that…

For the cert regs, piston aircraft are assumed to cruise at Vno (top of green). Turbine aircraft are assumed to cruise at/near Vmo/Mmo

So, for aircraft with Vmo/Mmo there are certification requirements beyond redline. Basically demonstrating that inadvertent exceedences beyond Vmo/Mmo due to turbulence, inattention, etc are recoverable. The speed margins are aircraft specific, and not published.

For aircraft using Vne there is nothing. Vne is the end of the known universe. The yellow arc is your margin. An aircraft that is completely uncontrollable 5 knots beyond Vne would be certifiable.

Turbine aircraft have to use Vmo/Mmo, so conversions have to convert. They could establish a higher Vmo/Mmo as part of the STC, but it would take extra flight testing and analysis.

Byron

Robinson R44 ~$600k
Robinson R66 ~$1.1m

$500k delta. They are very close aircraft and even share parts. Outside of the motor it's probably no more than $50-100k to build. Add in profit difference and I would venture that the RR300 is probably $250-300k more than the Lycoming.

Factory overhauls surprisingly close:

R44 - $310k w/ engine overhaul
R66 - $398k w/ engine PMI

Piston engines are getting expensive. Some are approaching $200k new. At that rate, twin engine pistons are DOA. It wouldn't surprise me if the G58 disappears in the near future. Just not competitive with SETP. 

7 years of 2005 Meridian ownership here.
1200 hours @ $223 per hour in total maintenance including annuals.
That's tires, batteries, everything and a Hot section included.
Only an occasional mid year stop for tires or simple squawks.
Never scrubbed a flight and 8-14 day annuals are the norm.

2025 annual will be >$50k as prop and FCU are due but wont hurt
the average much.
This aircraft and my full service shop allowed me to concentrate on work and family, not managing an aircraft, and has paid off with dividends! Retirement dividends

I have been penciling out jets for 5 years and the math, even Mike C's math, never worked out for me. I often fly with just one passenger and when i need to take 4 or more i just shuttle them from the nearest non stop commercial flight to our destination and everyone is happy.

This is a good point. For a jet prop or any turbine aircraft, one of the decisions I would be considering is maintenance. A good, local mx shop makes a huge difference. This is a big reason I sold the Meridian and went to the Citation. From now on, a plane I can get maintained relatively close to home will be one of the biggest factors.

When I flew a Bonanza there were multiple good shops around Houston and many more in Texas. The Meridian narrowed that down to a couple in all of Texas and none were convenient which is why I ended up taking the plane to the Kansas specialty shops.