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Turbine Reliability vs R44 piston

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Turbine Reliability vs R44 piston

Old 8th Dec 2008, 02:25
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Turbine Reliability vs R44 piston

there is a rise in R44 procurement in the market. how does the R44 top the list of most delivered heli at the present. is this even true? what is the top selling heli now? If it is R-22 and derivatives, is turbine engine reliability now a myth? please enlighten me.

I'm beginning to think of rushing to be checked out as R44 pilot for some reasons.
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Old 8th Dec 2008, 02:52
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I think drawing the conclusion that an aircraft is inherently reliable because there's more of them being made is something of a stretch.

Having said that, it can be said that manufacturers of aircraft have now adopted principles that maximise the reliability of the engines they choose to install.

In other words, I don't think engine "reliability" is much of a distinction nowadays.

Cost of operation however, is entirely a different matter for engines.


If reliability is a big thing for you, there are many other components that you may wish to consider.
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Old 8th Dec 2008, 04:24
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There's no doubt lots of statistics out there re piston vs turbine, but I'll rely on my own experience to pass judgement. In 3000hrs of Robinson flying I've had 1 stuck valve(R22), & 3 x magneto failures(R44). About the same turbine with no failures - Speaks for itself. My concern with R44's doesn't lie with the engine, but rather the MR Blades. Waaaay too many delamination cases for my liking. Otherwise a fantastic machine to fly & I don't think you can go wrong getting endorsed on one as they'll be around in great numbers for a long time yet.
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Old 8th Dec 2008, 06:46
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Turbine Reliability, Fact of Friction?
Are turbine engines really more reliable than pistons,
or is it a myth? The answer depends on the helicopter.


Article from Rotor and Wing Magazine:
http://www.skyhelicopters.com/ENG/TU...RELABILITY.pdf
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Old 8th Dec 2008, 07:19
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Interesting article Runway101. Its not written by this T Tucker is it ? -

T Tucker Response
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Old 8th Dec 2008, 07:31
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No way that's not him!!
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Old 8th Dec 2008, 10:33
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Just like apples and oranges, huh? Cant really say which is better. Depends on where you will use it for, is that right? What about usefulness then? Or purpose of flight? Or mission. Can I say then that if I use R-44 for chartered flights, tours and the likes, it would be better either economically for the charter company or for passenger because it will have cheaper cost with R44?

Well, what about marketability for the pilots? Can R44 rating be more marketable than a turbine rating? No offense to all R44 enthusiasts and operators, I know it is one good heli. A hell of a good heli.

Thanks fellas, really helpful but I need just a little more of it. Helppp!
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Old 8th Dec 2008, 17:47
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I'm beginning to think of rushing to be checked out as R44 pilot for some reasons.
Whoooaa.. there Nerf97, take it easy, sit down and open a beer. Im sure the feeling will pass
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Old 8th Dec 2008, 20:17
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In 3000hrs of Robinson flying I've had 1 stuck valve(R22), & 3 x magneto failures(R44). About the same turbine with no failures - Speaks for itself.

I'm no mathematician, but your experiences may not be statistically significant.i.e. 4 in 3000 (0.13pc) might not be any different from 0.0pc, statistically speaking.

Ive got 7000 hours on turbines and had to shut 1 down. Does that make it better or worse than the zero failures in 1000 piston hours?

D
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Old 8th Dec 2008, 20:48
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whyisitsohard - Statistics can be manipulated to suit whatever arguement a person is trying to present. I don't really care what is statisically significant, I care that on 4 occassions I was in a position where I had to make some decisions & take some action in order to compensate for a mechanical failure. It was pretty significant to me at the time.
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Old 8th Dec 2008, 23:00
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Heliduck,

You are quite correct of course, stats can be made to say whatever the presenter wishes them to say - partly the point I was making. And I accept fully that to you, at the time, the events were most significant indeed! But their significance merely prejudices YOU whilst still being of questionable mathematical significance. My own feelings are the same as yours though - after twenty years of flying and a life time's involvement, I also think pistons engines are less reliable than turbines. their very complexity seems to make it so! But will someone born today, after a lifetimes involvement with better piston engines, feel the same in forty years I wonder. And if the engines are so reliable, why do I have to practice a V1 cut every six months?? (rhetorical question!)

And yet, motor car piston engines seem to have reached almost clinical levels of reliability: and funnily enough, the CAA have nothing to do with cars. But that's probably a coincidence

keep it safe!
David
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Old 9th Dec 2008, 01:29
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An interesting point you make comparing earthbound reciprocating piston engines to airborne ones. It certainly highlights that aviation engines are on par with a 1960's morris minor when it comes to technology, but I think it is more to do with litigation lawyers than aviation authorities, although I agree that their abscence in the picture surely helps!! The example of Cessna shutting down for a few years due to court cases comes to mind.

Caterpillar mining equipment has had "glass cockpits" & computer controlled engine management systems for 20 years now, but put the same technology in an aircraft & it's considered cutting edge. I can't wait until Toyota start making helicopters, THEN we'll see a reliable engine!
You make a good point about people coming into the industry operating derated pistons far more reliable than the old B47's & H12's. Starting life with an unbiased opinion I think their attitudes overall will be different & the "turbine vs piston" debate will fade into the distance. Next time I fly a piston I'll just try not to think of all of those moving parts turning, burning & clanking around in there!
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Old 9th Dec 2008, 01:55
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Originally Posted by nerf97
how does the R44 top the list of most delivered heli at the present. is this even true? what is the top selling heli now?
Going by 2007 data, yes, the R44 is still by far the top-selling model with 664 units. Eurocopter doesn't appear to publish delivery data, but comparing their 2007 & 2006 fleet stats tables gives 161 AS350 deliveries for second place. The R22 is third with 159 deliveries, the EC135 fourth with 110, the B407 fifth with 73 and the EC120 sixth with 67.

I/C
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Old 9th Dec 2008, 12:16
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Robinson R44

Have flown the R44 derivatives Astro, Raven I, Raven II and the Clipper and Police version in addition to several other helicopter types including turbines.

Used them in training and Commercial operations.

The R44 is a curious beast in that it is almost in a separate class to to other helicopters due to being largely a work of modern technology (1980's and later) with a paradoxically vintage engine (Lycoming blueprint dates from 1940's).

Despite the, at first appearance, outdated powerplant, it performs surprisingly well and is in fact faster and more agile than some light turbine helos in my opinion.

To the world it has opened up previously unthought of applications for the helicopter due to it's low operating costs. It can be found flying in such varied conditions as the desert, to Polar regions and in major Metropolis'.


It compares very well in terms of reliability to alternatives and you can't honestly go wrong in getting yourself type rated as I have a good feeling that these choppers will be around for a while due to their inherent cost-effectiveness particularly in light of the current economic environment.
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Old 9th Dec 2008, 12:37
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.....if the R44 is so good....why the R66..
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Old 9th Dec 2008, 12:42
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" Why the R66 ? " .Because it's a bigger machine with 5 seats. Yes I know it's a turbine but as Tim Tucker told us on the last safety course I attended , Frank would have used a recip if there was one suitable.
R
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Old 9th Dec 2008, 15:10
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hmm... will be saving up for a type rating. (meditating deeply whilst viewing the blue waters and mild waves, cool breeze and warm sands of Mactan Island... thinking of inviting a heli enthusiast to discuss about R44 rating... )

Never mind the reliability issue, I guess I will leave it to the experts. What do you say fellas?
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Old 9th Dec 2008, 16:35
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Without having read Tim Tuckers article, I wonder why the magazine chose him to write about recip vs. turbine; they mind as well invite a representative from P&W or Turbomecca to do the same - the outcome would be quite predictable and opposite, I hazard to guess.
Talking about unbiased press


Just to stir the pot a little...
here the old second hand arguments I tend to agree with:

- car engine vs. aviation engine: the car engine spends most of its time at less than 30% of its power - Lycoming's 360's (in helos and fw) probably spend most of their life at more than 80% power (adjust numbers to your liking).

- in a reciprocating engine a lot of parts move at approximately 2,600 rpm in opposite directions; in a turbine only a few parts spinning in the same direction - although a bit faster.
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Old 9th Dec 2008, 17:22
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Phil77, with all due respect, but if you don't even bother to read available information on the subject (ie. the article) you are in the wrong topic in my opinion.

Go have a look, the article definitely sheds some light on the issue, of course it might be biased or not or not provide the answer after all, but Tim Tucker with his 18,000+ flight hours has been around for 40 years or so and flew from small to big and from turbine to piston everything. He was around when I was not even born and whatever he says can't be completely dismissed.

The article is also not asking you to stop believing turbines are more reliable, so it doesn't matter reading it I promise.

I am not on either side by the way, I am from a Robinson training environment but I wouldn't mind flying turbines and I certainly hope that both keep my blades spinning.
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Old 9th Dec 2008, 22:52
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Runway101
Ok, I did you the favor and read the article...

Let me forestall that I nowhere in my previous post questioned Mr. Tuckers experience or dedication - the dedication to his product is exactly what I was referring to: an executive of a company HAS to protect his own products and guess what, he did! He did not try to sell us that turbines are unreliable; but how wonderful reliable the engines are that his company uses! (pun intended )

Btw. I always thought the reason for the derated engine on robbies where savings in structural parts and transmission; its apparently super for reliability too! Actually proves my point with that auto engine comparison I made.
(I don't want to get into a p*** match between Schweizer and Robbie, but in a Schweizer I hardly ever flew at max power - but at least I was allowed to!)

I am also a little confused by his use of "early engines where less reliable", how much earlier than the '50s can it get? Using the same basic design and derating it makes 'em newer?

The article is headlined "Turbine Reliability: Fact or Fiction" next to a picture of a turbine. The fact is, that besides (unchallenged by me and others) lack of fuel economy, efficiency and power to weight ratio on the first page, there is no analysis of reliability of turbines, it is an essay about R22/R44 engines - which again was expected!

One last point: the good old statistics:
When I did my Robinson safety course (yes, believe it or not, I too have flown robbies!) the different statistics came in handy to argue the fact.
Questions: why using two different time frames to prove a point (maybe the number of engine failures on the R22 increased after 1997)? How many B206/MD500 vs. R22/R44 where actually flying? Is it good or bad that the primary cause "pilot error" is so large (was the pilot not able to control the helicopter because of design limits )?

My personal view is that the turbine engine is more reliable - but initially I just wanted to question the (naturally) biased opinion of the author for such an article...
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