Piston Vs. Turbine

[100'ToGo]

Which is more likely to quit?
Turbine would seem more reliable to me, considering everything is continuously spinning in the same direction.
However, I was talking with another pilot and he said everyone in his company prefer flying a piston.
Wondering what everyone else thinks?
Is there any statistics regarding the fail ratio of the two?

[mag check]

I believe Frank Robinson showed that a derated piston is more reliable than turbines, which is why he built the R44 with a piston.
The number one cause of an engine failure, piston or turbine is fuel starvation, so it really makes no difference at that point.
A well designed fuel system, and a pilot that puts enough fuel in the tank to do the trip, "almost" guarantee's there won't be an engine failure, no matter what type of fuel it's burning.

[200hr Wonder]

Interesting question, I did a little poking around and it seems that the Mean Time Between Failures for various aero engines are as follows:

MTBF for the PT6 Turboprop engine = 346,000 hours

MTBF Lycoming IO-540 engine = 10,000 hours

MTBF Honeywell TPE 331-10t engine = 150,000 hours

No I can't verify this information, it was after all just a Google search, however it seems to be logical from what I have experienced.

Know of several turbine shutdowns all due to a failure of one sort or another of the fuel delivery system. The pistons have been things like cylinder heads cracking and various other failures of large hunks of metal. This of course by no means an authoritative anything, just personal experience. I am not sure how a de-rated piston falls into this.

[Rowdy]

all the more reason for me to sit behind a Pratt.

Any stats on the ol' 985?

[North Shore]

Interesting question, I did a little poking around and it seems that the Mean Time Between Failures for various aero engines are as follows:

MTBF for the PT6 Turboprop engine = 346,000 hours

MTBF Lycoming IO-540 engine = 10,000 hours

MTBF Honeywell TPE 331-10t engine = 150,000 hours

No I can't verify this information, it was after all just a Google search, however it seems to be logical from what I have experienced.

Where did those stats come from? The manufacturers? I had an old CP who swore up and down that the reliability was the same, just that P&W didn't call it an engine failure if it was not their manufacturing that failed. However, fuel, oil, pumps lines etc can and do fail, leading to the engine quitting - but that's not P&W's fault. Thus high MTBFs....

[iflyforpie]

Here is the standard the PT6 meets for Commercial SEIFR (not wanting to open a can of worms here).

CASS 723.22
b) the turbine-engine of the aeroplane type must have a proven Mean Time Between Failure (MTBF) of .01/1000 or less established over 100,000 hours in service;

Not qualified is the term 'failure' which makes me think in flight shutdowns are not counted.

I could not find any stats on piston engines, but given the typical TBO is about half a turboprop or turboshaft, I think the MTBF would be around half as well.

One thing you have to remember about statistics is the dice have no memory or disposition. Contaminated fuel, shoddy maintenance, pilot error, manufacturer's defect, or an act of God will turn the engine's number up regardless of how reliable it supposedly is...

[Invertago]

all the more reason for me to sit behind a Pratt.

Any stats on the ol' 985?

I'd rather sit between two Pratts then behind one... alas that is another debate

[KAG]

I've had failures and shutdowns in both, I'd take a Turbine any day.

[SunWuKong]

However, I was talking with another pilot and he said everyone in his company prefer flying a piston.

Did he mention the reason?

It couldn't be for safety reasons anyway. Turbine is more reliable than piston, this is a hard fact, in addition planes equipped with turbine, most of the time, fly higher, faster, further, and have a better anti ice system and weather radar, all good when there is a thunder storm in the vicinity....

If for safety reasons there is no discussion, really.

[slam525i]

I believe Frank Robinson showed that a derated piston is more reliable than turbines, which is why he built the R44 with a piston.

You mean Frank Robinson as in the guy who just came out with the turbine powered R66? (I'm just being a jackass.)

Any debating between piston or turbine boils down to one thing: Cost (Initial purchase and operating) That said, if I had to bet my life on one engine, it'd be a PT6.

[mag check]

I believe Frank Robinson showed that a derated piston is more reliable than turbines, which is why he built the R44 with a piston.

You mean Frank Robinson as in the guy who just came out with the turbine powered R66? (I'm just being a jackass.)

Any debating between piston or turbine boils down to one thing: Cost (Initial purchase and operating) That said, if I had to bet my life on one engine, it'd be a PT6.

Yes, that Frank Robinson. Franks public reason for going turbine for the R66 was because Bell stopped prodution on the 206, so there is a market for a replacement.
I'm not positive, but I think he still stands behind the derated piston as being more reliable.

[sarg]

Personal experience says turbine. Approx 6,000hrs on each, no failures on the turbines and 4 in piston. On the opposed piston type oil pump failure, and one tossed a rod through the case, after the DMO signed off on the 50 hr. extention to TBO. R985 both were cracked jugs after the plane had been sitting for an extended period of time, got lucky on the R1340 never had a problem.

Derating any engine piston, turbine or jet greatly improves reliability and TBO.

[flying4dollars]

I've had failures and shutdowns in both, I'd take a Turbine any day.

+1

Suffering and engine failue in a Navajo fully loaded vs say a king air 200 or somethin? I'll take a turbine thanks.

[Tiger Moth]

It couldn't be for safety reasons anyway. Turbine is more reliable than piston, this is a hard fact, in addition planes equipped with turbine, most of the time, fly higher, faster, further, and have a better anti ice system and weather radar, all good when there is a thunder storm in the vicinity....

Except for the Caravan... that's a turbine with the best chance of falling out of the sky due to ice... even with all the extra ice equipment, like the foot long boots on the gear legs...

Though I do realize that you specified most of the time

And besides that, Jetstreams and those Garretts... you wanna talk turbine engine failures, take the apu-come engine there. I know our company has gone through a bunch of em...

I will take a pt6 anyday

Edited for finger-keyboard malfunction

[Turbofan]

A few years ago I had an engine fail on me.

At the time I had about 3500 hrs piston engine time
1000 hrs of twin turbo-prop
1000 hrs of turbo-jet

first engine failure was on a turbo-jet enigne.
cause...fuel starvation....blockage in the FCU...lots of fuel in the tanks!!

tf

[Hedley]

blockage in the FCU

Were you a little light on the Prist?

[SunWuKong]

Except for the Caravan... that's a turbine with the best chance of falling out of the sky due to ice... even with all the extra ice equipment, like the foot long boots on the gear legs...

You have a point, but (even though I specified "most of the time" ), what I wrotte remains valid, even without "most of the time": do you think the Cessna Caravan would be any safer with a piston engine?

Anyway yes the Caravan has an important fuselage compared to the power of its engine, and overall capabilities of this airplane's system.
This is a non-pressurized single engine airplane, and if you fly it with that in mind, you shouldn't find yourself flying into icing condition at 10 000 feet without doing something about it (descend, climb, change heading, divert...).
This bush airplane is one of the most useful in the history of aviation, you can find it up north canada, in france, in the indonesian jungle, in fact anywhere in the world.
This is THE bush airplane of the world. With a piston engine i am not sure it would had the same success today.

[Tiger Moth]

Caravan with a piston would be a horrid idea, I do agree.

There seems to be something in the Pilot/Operations end of things, however, that decided a turbine engine means it's good for anything. Not that I am bashing the Caravan, but its unfortunate it had to kill a few folks to make that point. I would still fly in it any non-icing condition day though!

[bcflyer]

Caravan with a piston would be a horrid idea, I do agree.

There seems to be something in the Pilot/Operations end of things, however, that decided a turbine engine means it's good for anything. Not that I am bashing the Caravan, but its unfortunate it had to kill a few folks to make that point. I would still fly in it any non-icing condition day though!

The plane didn't kill them, their own actions killed them. Flew the Caravan for 2000hrs in all kinds of weather (yes even in ice..gasp) and had no issues. It has limitations in place with regards to flight in icing. Follow the limitations and you won't have any trouble. Ignore them and........

Ok back to your regularly scheduled thread...

PS I would take a turbine over a piston anyday.. (although I gotta say I still love the sound of a radial on a cool fall morning.)

[peeelot]

I have 1300 hrs in a piston and 1 shutdown PA-31-350 and 1 failure C-337 Rear engine. I have flown about 2200 hrs in a machine with PT6's attached and never had a failure or even put into a situation where I was considering a shutdown. I would take the Turbine engine less moving parts less to fail on you.

[Hedley]

A good piston is better than a crappy turbine, but a good turbine is better than a good piston.

Once a turbine is running, it's pretty simple and reliable - it's the systems bolted onto it that are more likely to fail. No prist, etc.

I might mention that a carefully-maintained piston engine can be pretty reliable. I am very comfortable flying single-engine across the Great Lakes and the Gulf of Mexico in a single piston, if I am the one who performs all the maintenance on it since it came new from the factory.

Years ago, I once flew an old Apache which had 5500 SMOH on one side - a little Lyc four-banger. It was down south, so it had no cold starts, it flew frequently so it had no corrosion, and they just kept changing accessories and replacing jugs as required. Truth be told, the high time engine ran smoother than the "low time" engine on the other side!

[howard40]

The MTBF for turbines is very low. However I do wonder if they do the math for all events or just turbine failures. I have a feeling that if it goes down due to ice in jet fuel etc they don't count it as a turbine engine failure.
A Navajo uses say 34 gallons an hour, a cheyenne uses say 60 gallons an hour. A navajo engine is much much cheaper to overhaul than a PT6. In fact you could overhaul it about4 to 5 times for the price of a single overhaul of a turbine.
The Lack of avgas in places is starting to create a turbine only environment in the north.
If I had lots of money, and the customer would pay, of course I would rather a turbine.
I like the sound of an otter or a beaver in the morning... or a P51 anytime.

[bronson]

So far failures for me are at : piston-15
Turbine-0

[Hedley]

failures: piston - 15

You gotta stop flying junk A junk twin is still junk.

It doesn't matter if it's got the best paper in the world, you still know it's junk. The first fourteen engine failures you had should have been a hint!

[Lost in Saigon]

I have accumulated about 20,000 hours in about 35 years.

In the first 14 years I had 13 engine failures in 8,000 hours of piston time:

PA-28-151 (1)
C207 (1)
C310 (1)
C337 (3)
C402 (4)
C414 (1)
Canso (2)

In the last 21 years I have only had 2 engine failures in about 12,000 hours of turbine time:

Embraer 120 (1)
B767-300 (1)