Is the "Heavy" Piston Twin dead
Thread Starter
Is the "Heavy" Piston Twin dead
For as long as I can remember the heavy piston twin has been the aerial UTE of not just Oz but just about every part of the world. The Chieftain, C402, C404, Queenairs. Theres surely more types that I have forgotten. These can be found doing pax charters, hauling freight at night, bank runs and a myriad of other unglamourous duties.
Now we have a new breed, the C208 Caravan, TBM850, Kodiak, the Turbine Airvan, the new Kestrel turbo prop. All single engine turbines.
The new SE turbine aircraft are fantastic machines, they have performance that would have been unthinkable when the Chieftain and Cessna twins were designed, not to mention the Buck rogers avionics like the Garmin G1000.
But there is still one problem, turbine engines are still incedibly expensive to overhaul, and the cost goes way up if you do many short sectors as turbines also have a cycle limit. the overhaul cost of a PT6 or TPE engine is simply eye watering.....something like 250K, and thats a starting point.
So are the big pistons dead as a concept. Theres lots of new 350Hp engines around from Continental and Lycoming, both have FADEC which dont seem to have the reliability problems of the Chieftains J2BD engine. The Lycoming ie2 series engines looks promising but they seem to have gone quiet. RED aircraft engines is working on a 300Hp V6 diesel and a 500Hp V12 diesel( which looks suspciously like a take off of the Audi 6ltr V12 diesel as found in the Q7).
I'd like to see what could be done. Now an interesting aircraft would be a stretched Kestrel to seat 10, powered by 2 V12 diesels. Sounds perfect for a family SUV.
Now we have a new breed, the C208 Caravan, TBM850, Kodiak, the Turbine Airvan, the new Kestrel turbo prop. All single engine turbines.
The new SE turbine aircraft are fantastic machines, they have performance that would have been unthinkable when the Chieftain and Cessna twins were designed, not to mention the Buck rogers avionics like the Garmin G1000.
But there is still one problem, turbine engines are still incedibly expensive to overhaul, and the cost goes way up if you do many short sectors as turbines also have a cycle limit. the overhaul cost of a PT6 or TPE engine is simply eye watering.....something like 250K, and thats a starting point.
So are the big pistons dead as a concept. Theres lots of new 350Hp engines around from Continental and Lycoming, both have FADEC which dont seem to have the reliability problems of the Chieftains J2BD engine. The Lycoming ie2 series engines looks promising but they seem to have gone quiet. RED aircraft engines is working on a 300Hp V6 diesel and a 500Hp V12 diesel( which looks suspciously like a take off of the Audi 6ltr V12 diesel as found in the Q7).
I'd like to see what could be done. Now an interesting aircraft would be a stretched Kestrel to seat 10, powered by 2 V12 diesels. Sounds perfect for a family SUV.
Hardly call a PA31 or its ilk a 'heavy' piston twin. However I don't think they're dead. I fly a PA31 in charter in the US, and many other operators use pistons too.
The economics aren't always there for the turbines. Capital outlay, engine overhauls & insurance can be killer. Not so much engine overhauls if they're amortised properly over the TBO, but have one go tits up partway through the period and that throws a large financial spanner in the works.
Single engine turbines aren't always permitted to do what a twin can do: Fly overwater with fewer restrictions. It's a hell of a lot more feasable to operate a piston twin to the Bahamas than a C208 with passengers.
The economics aren't always there for the turbines. Capital outlay, engine overhauls & insurance can be killer. Not so much engine overhauls if they're amortised properly over the TBO, but have one go tits up partway through the period and that throws a large financial spanner in the works.
Single engine turbines aren't always permitted to do what a twin can do: Fly overwater with fewer restrictions. It's a hell of a lot more feasable to operate a piston twin to the Bahamas than a C208 with passengers.
Guptar, my Christmas gift to you is the following URL where you can read about all the traps and tears to be expereinced by anyone who thinks of adapting an automotive engine for aviation. As a general rule, it is a waste of time and money.
Aircraft Engine Conversions by EPI Inc.
Turbines are expensive because all of their hot section components are made out of the most god-awfully expensive, ornery and just plain difficult materials to cut, shape, form and join on the face of this planet.
Then of course you want some of those components like the cases wafer thin to save weight and trying to form or weld them is an exercise in frustration because of the potential for distortion.
The discs are made of the closest thing we have to unobtanium that is similarly difficult to do anything with, as are the blades.
Then of course you have the bearings, etc. and you want the whole thing to run in a gas stream Two hundred degrees hotter than the melting point of most of the metals at ridiculous RPM's.
The gears on a PT6 are American Gear Manufacturers Association (AGMA) class One, and their are bugger all companies that can make them. Been to P&W Canada, P&W Hartford, GE Lynn (military) and Cincinnatti (civil) you would be amazed at the tears and sweat that goes into any turbine engine.
Aircraft Engine Conversions by EPI Inc.
Turbines are expensive because all of their hot section components are made out of the most god-awfully expensive, ornery and just plain difficult materials to cut, shape, form and join on the face of this planet.
Then of course you want some of those components like the cases wafer thin to save weight and trying to form or weld them is an exercise in frustration because of the potential for distortion.
The discs are made of the closest thing we have to unobtanium that is similarly difficult to do anything with, as are the blades.
Then of course you have the bearings, etc. and you want the whole thing to run in a gas stream Two hundred degrees hotter than the melting point of most of the metals at ridiculous RPM's.
The gears on a PT6 are American Gear Manufacturers Association (AGMA) class One, and their are bugger all companies that can make them. Been to P&W Canada, P&W Hartford, GE Lynn (military) and Cincinnatti (civil) you would be amazed at the tears and sweat that goes into any turbine engine.
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I'd like to see what could be done. Now an interesting aircraft would be a stretched Kestrel to seat 10, powered by 2 V12 diesels. Sounds perfect for a family SUV.
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Theres lots of new 350Hp engines around from Continental and Lycoming, both have FADEC which dont seem to have the reliability problems of the Chieftains J2BD engine. The Lycoming ie2 series engines looks promising but they seem to have gone quiet.
Their only problem was the POH's and the way pilots were taught to operate them. Add to that LAME's who may not have been diligent at setting them up properly.
It beats me how so many of them do so well when you see how they are treated.
FADEC on piston aero engines...... Nice idea but you can only improve the BSFC of an engine so far, and you can do it without FADEC. If varying fuel grade is your concern in big HP turbo's these FADEC's are not going to help there either. A good JPI/Auracle or similar and a pilot with knowledge = reliable power plant.
Thread Starter
Very interesting article bout the Orenda V8, when it came out I was hopeful about the engine but my fears were realised, it simply weighed too much.
But it does appear the cabin class piston twin is dead. Yes there are plenty of old airframes out there, but they are getting older and older. Even the Lock and Key Chieftains from Mike Jones Aiircraft while beautiful, are still at least 25 years old.
At present, you simply cant buy a new cabin class piston twin.
Interesting article on aerodiesels
http://bmepinc.com/AEHS%20presentati...%2005%2008.pdf
But it does appear the cabin class piston twin is dead. Yes there are plenty of old airframes out there, but they are getting older and older. Even the Lock and Key Chieftains from Mike Jones Aiircraft while beautiful, are still at least 25 years old.
At present, you simply cant buy a new cabin class piston twin.
Interesting article on aerodiesels
http://bmepinc.com/AEHS%20presentati...%2005%2008.pdf
Last edited by Guptar; 9th Dec 2012 at 21:17.
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Why Not Consider: A Lock & Key RENOVATED NAVAJO and possibly get more utility for your money?
I operate a Mike Jones' 'Lock & Key' Navajo. It's really nice - and has better equipment in it than a Beechjet I fly. You pay a premium for them though. You're paying for someone's work to have something that's ready to go as soon as you sign on the dotted. None of this 'buy an airframe, send it out to have the interior, avionics & paint done. Oh, and add various STCs while it's being done' carry on.
You could have the same result without going to Mike Jones, but you'd have to do the legwork & organisation and wait for it to be done.
At the time this one was done Mike Jones didn't include an EDM so I had the owner put one in after I took over managing it. The EDM has been worth every penny and easily paid for itself in fuel savings, decision making that avoided a stranded aircraft+pax when I had an injector line break, and maintenance time for troubleshooting the occasional issue.
This one has only about 2,500 hours on it. Might be a couple of hundred more (don't have its paperwork with me) but it's well under 3,000.
You could have the same result without going to Mike Jones, but you'd have to do the legwork & organisation and wait for it to be done.
At the time this one was done Mike Jones didn't include an EDM so I had the owner put one in after I took over managing it. The EDM has been worth every penny and easily paid for itself in fuel savings, decision making that avoided a stranded aircraft+pax when I had an injector line break, and maintenance time for troubleshooting the occasional issue.
This one has only about 2,500 hours on it. Might be a couple of hundred more (don't have its paperwork with me) but it's well under 3,000.
Last edited by Tinstaafl; 9th Dec 2012 at 21:44.
Thread Starter
Bill Brogden seems to think this is the most promising of the aerodiesels.
http://bmepinc.com/AEHS%20presentati...%2005%2008.pdf
There was a flurry of press releases a couple of years ago about Lycomings iE2 series but it seems to have gone quiet lately.
http://www.lycoming.com/news-and-eve...iE2_Engine.pdf
http://bmepinc.com/AEHS%20presentati...%2005%2008.pdf
There was a flurry of press releases a couple of years ago about Lycomings iE2 series but it seems to have gone quiet lately.
http://www.lycoming.com/news-and-eve...iE2_Engine.pdf
The Real Issue
The aviation industry doesn't set the trends, insurance and risk does.
'Heavy' piston twins are already being squeezed out from the top down. The operating economics do not matter to customers as much as many operators think; as they will pay for what they require (ie. twin turbine multi-crew is a common insurance/audit requirement).
The low margin customers will charter piston-twins for as long as they can get away with it, but I think you will see a trend toward multi-client charters on larger turbine aircraft in the long term.
The BARS and OGP (among others) requirements will see the end of the piston twin in the majority of non-subsidised charter operations in this region. As will client's growing desire to simplify charter routes by removing stops and aircraft changes (ie flying short international sectors direct from mine-site aerodromes in turboprops).
'Heavy' piston twins are already being squeezed out from the top down. The operating economics do not matter to customers as much as many operators think; as they will pay for what they require (ie. twin turbine multi-crew is a common insurance/audit requirement).
The low margin customers will charter piston-twins for as long as they can get away with it, but I think you will see a trend toward multi-client charters on larger turbine aircraft in the long term.
The BARS and OGP (among others) requirements will see the end of the piston twin in the majority of non-subsidised charter operations in this region. As will client's growing desire to simplify charter routes by removing stops and aircraft changes (ie flying short international sectors direct from mine-site aerodromes in turboprops).
Piston twins are now not worth much more than engine value. Its getting very hard to find good low time "working" twins (eg PA31). Many corporates are now mandating turbines.
The Charter market will always prefer twins for the image of the second engine. King Airs are currently taking over from Chieftans. The freight market will move to single turbines (eg Caravan). Tourist operators will use what makes sense to them (C210, C206 Airvan, etc). The piston twin will become the domain of dinosaurs like me who like the speed & security of a twin for IFR and use the aeroplane for business a little. Twins with good support (Seneca , Baron, Aerostar) will have a good future. The others (especially SID requirement Cessna's) will fade away. You can see this happening with C310 prices now. Chieftan parts are getting hard to get & expensive now and the source of good low time ones (for fleet rejuvenation) has all but dried up.
But I could be wrong.
The Charter market will always prefer twins for the image of the second engine. King Airs are currently taking over from Chieftans. The freight market will move to single turbines (eg Caravan). Tourist operators will use what makes sense to them (C210, C206 Airvan, etc). The piston twin will become the domain of dinosaurs like me who like the speed & security of a twin for IFR and use the aeroplane for business a little. Twins with good support (Seneca , Baron, Aerostar) will have a good future. The others (especially SID requirement Cessna's) will fade away. You can see this happening with C310 prices now. Chieftan parts are getting hard to get & expensive now and the source of good low time ones (for fleet rejuvenation) has all but dried up.
But I could be wrong.
Thread Starter
Turbine for commercial ops, charter etc is fine, but there is a no choice for the private owner who has a different set of requirements. The private GA sector grew on aircraft that could haul the wife and 4 kids plus all their gear, surfboards, bikes etc, perhaps even the family dog. Most of these owners flew very short sectors, often as short as half an hr.
The Baron, Seneca and Aerostar, all great aircraft are too small.
The C208, PC12/King Air etc while fantastic aircraft, lots of start cycles on the engine will make it horrifically expensive.
Not to mention the bank runners who can do 4 hrs a day but with up to 20 hops.
Its seems a whole sector of the industry is being ignored.
The Baron, Seneca and Aerostar, all great aircraft are too small.
The C208, PC12/King Air etc while fantastic aircraft, lots of start cycles on the engine will make it horrifically expensive.
Not to mention the bank runners who can do 4 hrs a day but with up to 20 hops.
Its seems a whole sector of the industry is being ignored.
Being a bit of a newbie myself especially when it comes to the financial side of Aviation I have a few questions.
Most of you have mentioned how Turbine powered aircraft like the C208, Pac750 etc... aren't as economical for shorter hops because of the engine cycles, when you talk about Engine Cycles i'm assuming you're referring to the Startup/Shutdowns. Could this short fall not be easily solved by the use of multi-crew/ground crew which then removes the need to shut down?? I understand these crew would be an extra cost of course but certainly there would be ways to absorb these costs either by either contracting people to do the work only on the days you need them or at no extra cost for companies with existing ground facilities.
How does the use of leased engines by companies who specialise in overhauls reduce the costs?? I'm referring to buying the Airframe but leasing the engine which is then simply swapped out for another engine that is delivered, ready to go with the other engine then being sent away to the leasing company for overhaul who can do the job cheaper in their own facilities with their own staff?
Also a lot of companies these days seem to be coming around to the reliability of newer Single Engine Turbine Aircraft as opposed to older Twin Pistons which is reflected by some mining companies now allowing their staff to transfer on them so would this not also make them a more viable option?
Most of you have mentioned how Turbine powered aircraft like the C208, Pac750 etc... aren't as economical for shorter hops because of the engine cycles, when you talk about Engine Cycles i'm assuming you're referring to the Startup/Shutdowns. Could this short fall not be easily solved by the use of multi-crew/ground crew which then removes the need to shut down?? I understand these crew would be an extra cost of course but certainly there would be ways to absorb these costs either by either contracting people to do the work only on the days you need them or at no extra cost for companies with existing ground facilities.
How does the use of leased engines by companies who specialise in overhauls reduce the costs?? I'm referring to buying the Airframe but leasing the engine which is then simply swapped out for another engine that is delivered, ready to go with the other engine then being sent away to the leasing company for overhaul who can do the job cheaper in their own facilities with their own staff?
Also a lot of companies these days seem to be coming around to the reliability of newer Single Engine Turbine Aircraft as opposed to older Twin Pistons which is reflected by some mining companies now allowing their staff to transfer on them so would this not also make them a more viable option?
Its seems a whole sector of the industry is being ignored.
I guess there is always the possibility that the likes of the Chieftain might go the way of the Cub and Piper sell off the rights to someone else to resume manufacture of the PA31.
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Thats how we ran them in Botswana Ixixly. We were doing anywhere between 15-20 hops a day.
We would pull onto a concrete pad and feather. Put a barrier between the prop and the cabin then roll a set of stairs up to the cargo door and let the passengers out. The air stairs on the right hand side were a bit hard to use because the exhaust is on that side and it gets a little warm.
Turn around times were also great. Could unload 12 pax, then load another 12 pax, brief them, takeoff checks and be airborne in 4 minutes.
Caravan makes a lot more economic sense with the amount of money they make in between overhauls if they are operated to capacity.
A 1hr flight and you can haul 3000lbs. Try that in a piston twin.
We would pull onto a concrete pad and feather. Put a barrier between the prop and the cabin then roll a set of stairs up to the cargo door and let the passengers out. The air stairs on the right hand side were a bit hard to use because the exhaust is on that side and it gets a little warm.
Turn around times were also great. Could unload 12 pax, then load another 12 pax, brief them, takeoff checks and be airborne in 4 minutes.
Caravan makes a lot more economic sense with the amount of money they make in between overhauls if they are operated to capacity.
A 1hr flight and you can haul 3000lbs. Try that in a piston twin.
Here's an interesting insight into owning a turbine engine. Flying magazine contributor Dick Karl owns a Piper Cheyenne, recently had to do a hot section inspection on one engine, turns out some guide vanes were burned through. That ment that the next stage turbine blades had to be replace.
58 X $265.00 = $15,300....for parts alone, not labour for the HSI. He doesnt mention if any other work needed to be done.
Eye watering.
Edit, page 2 has a list of work.
Turbine blades $15,300
Vane ring $7,900
IR duct $3,714
Parts Total $37,531 + Labour $8,370 for a grand total of .......
$45,901........and this was for an angine that was working fine, just that it came up for a sceduled HSI.
Maintenance of An Older Airplane | Flying Magazine
58 X $265.00 = $15,300....for parts alone, not labour for the HSI. He doesnt mention if any other work needed to be done.
Eye watering.
Edit, page 2 has a list of work.
Turbine blades $15,300
Vane ring $7,900
IR duct $3,714
Parts Total $37,531 + Labour $8,370 for a grand total of .......
$45,901........and this was for an angine that was working fine, just that it came up for a sceduled HSI.
Maintenance of An Older Airplane | Flying Magazine
Last edited by nomorecatering; 10th Dec 2012 at 00:22.
'Hot' turn arounds are used quite often to save cycles in various turbines, ( Van's/PAC's's's etc for meat bombing and even RPT). No problem as long as the SLF is kept from the spinny point end.
Ixixly, yes its heat cycles that do the damage, although thats not exclusive to turbines...pistons dont do so well starting and stopping 10 times a day. GTSIO-520 engines spring to mind...
Ixixly, yes its heat cycles that do the damage, although thats not exclusive to turbines...pistons dont do so well starting and stopping 10 times a day. GTSIO-520 engines spring to mind...
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Ixixly,
Having ground crew to shepherd the pax means...you must have ground crew in place. I fly charter and corporate flights that, at the moment, can go anywhere withiin the US and can be on little to no notice. Soon that will include the whole of the Caribbean. I used to do similar in Australia. It's not practicable to employ someone at every airfield in the US just in case we should stop by. If we carry someone then that's at least one fewer pax, less baggage &/or shorter range.
'Power by the Hour' & similar schemes doesn't necessarily reduce the hourly operating cost, except for nasty surprises. You're effectively paying for someone else to take the risk and they want their profit margin on top of that cost. Insurance is never free or cheap, just cheaper than a calamity you can't afford to risk.
Many jurisdictions prohibit or severely restrict single engine ops compared to multi. Try doing flights overwater, or at night, or IFR in various countries and the op. is only practicable in a twin. Shetland, for example, is an area where a PAC750XL would be great - short(!) strips, short hops, limited number of sectors per day - but the overwater nature, and need to resort to IFR when the weather closes in, makes it not possible under . In the US, single engine is OK for IFR charter but then you have weather & overwater limitations that don't apply to twins.
Having ground crew to shepherd the pax means...you must have ground crew in place. I fly charter and corporate flights that, at the moment, can go anywhere withiin the US and can be on little to no notice. Soon that will include the whole of the Caribbean. I used to do similar in Australia. It's not practicable to employ someone at every airfield in the US just in case we should stop by. If we carry someone then that's at least one fewer pax, less baggage &/or shorter range.
'Power by the Hour' & similar schemes doesn't necessarily reduce the hourly operating cost, except for nasty surprises. You're effectively paying for someone else to take the risk and they want their profit margin on top of that cost. Insurance is never free or cheap, just cheaper than a calamity you can't afford to risk.
Many jurisdictions prohibit or severely restrict single engine ops compared to multi. Try doing flights overwater, or at night, or IFR in various countries and the op. is only practicable in a twin. Shetland, for example, is an area where a PAC750XL would be great - short(!) strips, short hops, limited number of sectors per day - but the overwater nature, and need to resort to IFR when the weather closes in, makes it not possible under . In the US, single engine is OK for IFR charter but then you have weather & overwater limitations that don't apply to twins.