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Leap & CFM56

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Leap & CFM56

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Old 14th Jan 2018, 09:51
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Hello everyone,

It's been a while since I've been able to return to this beautiful community of professionals in a field that I love, aviation and aeronautics, even if unfortunately I could not make my profession of it ... Oh and with a little delay I wish you all a happy new year 2018. Moreover, I beg my English-speaking readers to apologize for any clumsy aeronautic formulations in english because I am French-speaker.

The Leap engine is about to succeed the CFM 56 I think in the coming decade. So I'm wondering when the production line of the latter engine will definitely be stopped. It seems to me that today it remain only the -5B and -7B variants on the 737 NG and the A320 ceo . I hypothesize that the production of the CFM 56 will definitely be stopped with the complete replacement of the 737NG and A320 ceo fleets through the world ... Could it be possible however for these aircrafts to be updated with Leap engines?

I still find quite limiting for customers of the 737 MAX family the unique choice of the Leap 1B engine, even if the PW1000G GTF still seems to know some sins of youth ... Why have imposed this unique engine?

In the impatient expectation of your kind answers.
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Old 14th Jan 2018, 12:02
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Well, take a close look at a LEAP-1B, and tell me that you don't find it in any way similar to a CFM56

Its still made by CFM, comes in equivalent thrust ratings to the CFM56-7B, and is probably closer to the -7B than the -3B is to the 7B
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Old 14th Jan 2018, 12:54
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The 7BE has been in production since 2014. The wing is hte same, more or less, so re-engining is perfectly possible, however, with the life expectancy of most CFM engines being very good, the real question is will the number of -NGs going to the boneyard provide enough to keep the new build NGs in the air for the next 30 years. Probably more than likely.

The reason for the single supplier is cost saving for Boeing. One thing that really blows costs out of proportion, is too many options and choices. Airbus must be rueing the day they gave in on that with the A380....
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Old 14th Jan 2018, 13:08
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The Leap 1B engine is also heavier by a few hundred kg's compared to the CFM56, so I don't think a "simple" re-engining is possible. They had to increase strength of some structural components.
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Old 14th Jan 2018, 18:33
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The CFM56-7B will remain in production as long as Boeing is still building P-8s. It would cost a not so small fortune to recertify the P-8 with the Leap - too much to be justified for a relatively small production run.
I don't expect to see the NG re-engine with the Leap. The integration of the engine with the airframe makes it cost prohibitive (this is true for most modern airliners).
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Old 15th Jan 2018, 13:48
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Hello everyone,

I thank you for your participation. I answer each of you point by point by broadening the debate:

STBYRUD said

Well, take a close look at a LEAP-1B, and tell me that you don't find it in any way similar to a CFM56

Its still made by CFM, comes in equivalent thrust ratings to the CFM56-7B, and is probably closer to the -7B than the -3B is to the 7B
First of all STBYRUD your answer seems to me a little off topic, I did not speak of comparison between the performance of the CFM56 and the Leap, but the moment when will be decided the stopping of the chain of the CFM56, and the total replacement of this engine by LEAP.
But even so, I doubt that motorists would commit millions of dollars and a program of 5 years of research and development (is the rule for any new engine in this sector) to produce machines without real progress for airlines customers both in terms of consumption performance and engine thrust ... The standard for current engines is a dillution rate of 9 when at the time of the first CFM56 when reaching the 7 was a feat !!. ..And according to Safran Engines, the CFM56-3 thrust range was 82/105 kn compared to the 124.5kn of Leap 1B !
I think in fact that the current goal of any motorist is to lighten up the entire reactor by using more and more composite or other alloys conferring endurance and strength especially for blades of compressors and turbine , and the resistance of the combustion chamber, to space maintenance cycles, and to refine more and more the specific consumption by improving the dillution rate to give more autonomy to the aircraft equipped.

RVF750

The 7BE has been in production since 2014. The wing is hte same, more or less, so re-engining is perfectly possible, however, with the life expectancy of most CFM engines being very good, the real question is will the number of -NGs going to the boneyard provide enough to keep the new build NGs in the air for the next 30 years. Probably more than likely.
I think that a remotorization is not directly related to the type of wing but rather with the ancillary equipment accompanying the operation of the reactor: the kerosene circuit is it the same, the pumps are they the same, are the various accessories out of the engine block the same for a CFM56 as for a LEAP? If not, is their replacement expensive in addition to installing the new engine?
On the other hand, I would be interested to know the elements that determine the maximum life of a reactor in general, and different variants of the CFM56 more precisely (if possible)? Which elements of the reactor wear out the most and which others are so vital that it is necessary to replace it with a new engine? For how many hours of flight are the current CFM56-7Bs expected compared to LEAP?
Do not the conditions of use of an airplane affect the life of a reactor: for example low-cost airlines that have the practice of using their aircraft at the maximum of the number of hours they can do per day, and therefore the multiplication of takeoff cycles where the engines give their full power, does it not reduce more the life of the reactors that equip them than in other companies generally state?
The climatic environment in which reactors commonly operate can also, in my opinion, affect the overall service life of a reactor: if, for example, it is in a salty climate, the wear of the parts will be greater than for an aircraft operating in mountainous areas do not you think?

RVF750

The reason for the single supplier is cost saving for Boeing. One thing that really blows costs out of proportion, is too many options and choices. Airbus must be rueing the day they gave in on that with the A380...
Regarding the variety of engines proposed by an aircraft manufacturer, I think that opposite to you it gives the choice to companies to refine the performance of their aircraft in terms of operating costs and autonomy, and to play competition between engine manufacturers in terms of the performance of engines that each offers in terms of maintenance cost, endurance, and adaptation to noise and ecological standards. I think in fact that it is not up to the aircraft manufacturer to impose a particular type of engine, unless it has difficulties of integration with other competing models. It is true that for the Leap the nacelle of 737 MAX has been modified, but I do not know if it really is what dictates the only choice of this engine.

And finally another question to come back to our subject, is the production line of an engine stops automatically with that of an airplane (so with the chains of the A320 ceo and B737NG), or is it maintained for the used aircraft market for spare parts? Since planes are generally intended for a maximum lifespan of 40 years, the 737NG and A320 ceo will not leave the scene until 2030, is to say that the CFM56 continue to exist until that date?

Last edited by Yan104; 15th Jan 2018 at 14:17.
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Old 17th Jan 2018, 14:40
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The production of the CFM 56 will be on for the next 15 years for sure.
With that many air-frames needing new engines before frame is scraped.
I never fly aircraft older then 10 years, and every so often I see an " old " one with one new engine.

The rate of production is hard to tell this early.

Are You asking because You work for the Manufacturer"
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Old 17th Jan 2018, 21:13
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When the new aircraft market goes away, the engine will go out of production soon after. The engine manufacturer will calculate how many spares will be needed to support the fleet through the expected retirement, build that many engines, then shutdown everything aside from the normal consumable spares (things like turbine blades and 'life limited' parts). It's simply not cost effective to maintain a production line that's only making a few spare engines. And, even a huge fleet of engines such as the CFM56-5 or -7 won't need that many additional spares - as aircraft get retired those engines are often overhauled and put back into the spares pool. Look at something like the JT8D - something like 10,000 manufactured with many still flying around, but Pratt hasn't built a new JT8D in nearly 20 years.
That being said, the CFM56 is still scheduled to go on new build aircraft for several more years - it won't be going OOP anytime soon.
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Old 17th Jan 2018, 22:32
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Quick comment with regards to the comment of being able to re-engine a NG with the Leap...

To fit it on the Max they had to raise the nose gear by 8 inches to accommodate the larger diameter fan and then added jiggery magic with the spoilers to maintain the landing attitude etc and that is the few highlights of what is different to connect the larger engine.

I can't see it happening.. the CFM in it's current guise is a very reliable economic engine and while the leap is more economic I can't see fuel getting high enough in price to cover those mods if it is even possible.. certification costs etc would be wildly prohibitive.
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Old 30th Jan 2018, 08:01
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Hello everyone,

With a little delay because I have been busy lately, I thank you for your interesting interventions. I resume the content point by point again:

  • BluSdUp

The production of the CFM 56 will be on for the next 15 years for sure. With that many air-frames needing new engines before frame is scraped.

I never fly aircraft older then 10 years, and every so often I see an " old " one with one new engine. The rate of production is hard to tell this early.

Are You asking because You work for the Manufacturer"
Alas I could not join the aeronautics sector although I was dying for it, and so I do not work at any engine manufacturer ... But as I am eagerly documenting on the world of civil aviation and airplanes, their designs, their operations etc ... it comes to me questions about articles that I read in specialized magazines ... I agree with you that the presence of the CFM56 will last at least a fortnight. years if not longer with the life of the 737 NG, the 737 MAX begin barely marketing them.

  • tdracer

You cite as an example one of my favorite engines the JT8D, which I knew during my childhood in the 80s, certainly noisy, greedy and well-known by pilots by their soft in terms of thrust !! ... So you confirm that the withdrawal CFM56 will most likely occur with the final withdrawal of 737NG which I think will not happen before 2 good decades, not counting their re-circulation through the second-hand market.
I understood from your explanations that some reactors are re-conditioned either for a return to service or to serve as spare parts, I also heard of a second-hand market and renting even for engines, could anyone tell me how it works? Is it not highly regulated for obvious security reasons, and if so which institution controls it? Can engine manufacturers not oversee such a market to avoid dubiously deadly contraband?

  • TangoAlphad

I suspected that there would be difficulties reengineering the 737NG by Leap given the modifications it imposed on the 737MAX, which were anyway part of a global evolution scheme of this family of aircraft ... So the Leap for Boeing will remain dedicated to the 737 MAX, but will not pose I think re-motorization problem for the A320 ceo already adapted to large diameter engines and with the origin of landing gear lower than the previous generations of 737 ... With all the same some reserve on the medium-term existence of the A320 ceo of the first series (produced between 88 and 92) which exceed the mid-life currently ...

To conclude with regard to the maintenance and the availability of spare parts for devices whose production lines were stopped, I thought of the solution of their production on the maintenance sites of the airlines yet with the modeling machines 3D. It would be possible according to manufacturers' standards to reproduce a perfect copy and perhaps even with improved materials of these parts ... Nevertheless the problem that would arise would be that of their approval in short time by the FAA and manufacturers, a dedicated service should be created and put in place a fast coordination between the maintenance services of companies and these institutions: what do you think?
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Old 30th Jan 2018, 15:04
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As long as NG and military equivalents are produced the engine will remain in production.
In fact even afterward to ensure replacements are available.
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Old 30th Jan 2018, 19:36
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I also heard of a second-hand market and renting even for engines, could anyone tell me how it works? Is it not highly regulated for obvious security reasons, and if so which institution controls it? Can engine manufacturers not oversee such a market to avoid dubiously deadly contraband?
There are two basic systems for spare engines. First is obvious - the airline/operator will typically keep a number of spare engines to support their needs. That number will be dependent on the size of their fleet. But there is a second pool of spares which is owned and run by the engine manufacturer. This is used to support small operators who don't want to maintain their own set of spares, but it is also used to support operators who unexpectedly 'run short' - either do to bad luck or poor planning. The number of engine manufacture 'pool' engines is increasing with the growing move towards 'power by the hour' - where operators don't own any of their engines - they lease them from the manufacture and pay a rate based on usage.
When an aircraft gets scrapped or otherwise removed from service, the engines are usually removed - at which point they can also be scrapped (there is considerable scrap value in just the materials, and some parts can be re-conditioned and reused), or overhauled and put in the spares pool.
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Old 1st Feb 2018, 08:30
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I think Skyjob that the military market for a manufacturer of civil aircraft does not produce to my knowledge of fighter jets is a niche market with limited outlets ... That said I do not know how many copies were ordered P8A-Poseidon by the USAF or if they will be successful with other countries than the USA ...
As for the 737NGs, I have no idea how many copies are in circulation in the world today and how many will continue to come out of Boeing's mills until the complete shutdown of their chain, and I think it's these numbers that will condition the maintein on the market CFM56-7, not to mention also the A320 family ... I do not know if the Neo version will only be equipped with Leap or could also integrate the CFM56-7 (I think it there is a specific version called "Tech Solution" for these aircraft) in addition to the PW1100 G ... Anyway the CFM56 will obviously still be there for decades! ... And it is also a certainty that from my discussions here: the 737-MAX can only take Leap 1B unless the manufacturer decides later and once the PW 1100 G has gained reliability to integrate it into its catalog ...

tdracer, I thank you for your explanation of the second-hand engine market. The management of the fleet of engines must still be quite complex in companies whose fleet is diversified with the short, medium and long-haul poles ... To be able to evaluate the number of engines "tanks" of spare parts for each type of aircraft, it is necessary that the maintenance service of the company has a complete history of the maximum lifetimes of each element of turbo-machines observed to their use over years !! ... For the medium-haul fleet concerned by the CFM56, I think it should analyzed the various uses made of the 737 or A320 and the cyclic constraints imposed on the engines, for example on lines of short and medium radius action. Do not you think that lines of short radius action with high frequencies of flight are more difficult for the engines of a plane than the lines of medium range (between 2:30 and 5 hours maximum flight), because of closer take-off cycles?
It is true that both aircraft manufacturers and engine manufacturers are starting to develop their after-sales services considerably, with the operational monitoring of their machines at their customers, both in terms of diagnostics and maintenance service offerings. and I am reassured that they are the ones who oversee the engine rental market: but how is concretly evaluated the cost of using each of the parts rented for the engines, or possibly the rental of the entire engine?

And what about the use of 3D machines for the autonomous production of spare parts for which the production of manufacturers has stopped? What potential problems can this pose?
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