Leeham News and Analysis
There's more to real news than a news release.
Leeham News and Analysis
- Bjorn’s Corner: Air Transport’s route to 2050. Part 5. January 17, 2025
- What’s the future of the Boeing 787-8? January 16, 2025
- FAA understaffing affects air operations oversight; NTSB falls short, too January 13, 2025
- Bjorn’s Corner: Air Transport’s route to 2050. Part 4. January 10, 2025
- The market is ready for a 787F. But is Boeing? January 9, 2025
CFM gets FAA and EASA certification for a more robust LEAP-1A turbine.
By Bjorn Fehrm
December 10, 2024, © Leeham News: CFM has announced that FAA and EASA have certified an upgrade to the LEAP-1A turbine, allowing the engine to stay on wing longer, especially in hot and harsh environments.
The upgrade was developed using a new dust ingestion method CFM developed to simulate the wear on the LEAP first turbine stage and nozzle in certain dusty environments.
CFM LEAP-1A with the booster bleed ports marked with (2) and the turbine that has been improved marked with (7). Source: CFM.
The challenge of keeping dirt, dust, and ice out of the Turbofan core.
Engine manufacturers use several methods to protect their Turbofan engine cores from stones, dirt, dust, and ice that get sucked into the engine through the fan.
The first protection stage is the shape and design of the fan’s spinner. Its curvature forces heavier debris to be spun into the fan area outside the engine’s core entrance.
For the particles that still enter the core, the LEAP has inward-opening booster bleed doors between the booster stage and the main compressor (at 2 in the picture). As the particles swirl into the core, they follow the outer curvature of the core inlet. During takeoff and landing in a harsh environment, the bleed doors can be kept minimally open, just enough to catch the particles sliding on the outer intake slope. The particles are then vented into the fan stream.
Dust particles not caught by the spinner and bleed doors can find their way into the turbine cooling bleed air tapped from the compressor ( 5 in the picture). As this air enters the narrow cooling paths of the first turbine stage nozzle and blades ( 7 in the picture), it can damage and clog these cooling passages.
It’s been a challenge to simulate this during turbine development, as the dust particles must be precisely the size where they make it into the turbine cooling. CFM engineers have worked with geologists to find and reproduce the dust type that causes the problem. This dust was then ingested into ground test engines using a special dust ring.
The LEAP dust ingestion rig. Source: CFM.
The same deterioration could be seen as deteriorated blades and nozzles taken from the field. Blade and nozzle developers could now test new cooling arrangements in the dust rig and know they would be effective in the field. A new nozzle and blade type that alleviates the problem has been developed.
It’s now certified to replace the present parts for the LEAP-1A that powers the A320neo family. The updated parts for the 737 MAX are being tested and will be certified in the coming months.
Engine mfgs make changes all the time to the engines. I have not seen that they were certified as such.
P&W has done a combined upgrade to the GTF.
Is this new or is it just a PR piece by CFM?
@TW
Yea interesting. A new T1B is certainly usually a big deal, but usually doesn’t mean a re-cert. it is not a fundamental architecture change.
Reading deeper it looks more like an entirely new 1st turbine stage suite of parts. Wonder if they changed the bleed air too?
Normally adjustment to cooling flow and coatings. This time more parts might need modifications to deliver more cooling air. RR same problem on T1000 T1 blade certified and flying on T7000 but FAA not approved it as they demand testflights on 787 it looks like
EASA and FAA have dual recognition of each others certification.
Except when it doesnt suit FAA and US manufacturers
I think everyone here understands the certification recognition between EASA and the FAA.
EASA has been the one that put a stop to automatic and rightfully so.
As far as I know the FAA has asked for clarification on the Airbus fusalge fuel tank for the A321, EASA had wanted more as well.
If you have an example of FAA and what you say are US Mfgs I would like to see it.
I think both AHJ get arm twisting from their respective mfgs.
Equally I think its good that things get challenged both ways and not just an automatic. We would have two fewer crashes and 347 people would still be alive.
Its worth noting that Brazil caught part of MCAS and had it put in their manual. The issue behind it was not caught but if everyone had been cross checking it might have been.
EASA has put the onus on the FAA/US for Synthetic AOA and speed. Its a shame they have not done the same for Airbus as there are a number of speed failures as well as AOA ice up. Its a bad system subject to a common failure and the tech obviously is there to stop it.
But they also failed to insist that 787s in Europe not fly with two iffy engines and India lead the way on that in insisting that no aircraft should fly with even one iffy engine.
Rather than automatic if they checked each others work all the time, it would be a better system.
Guessing they changed cooling hole pattern as well. But with particle debris the solution almost has to be upstream. Not sure what you can do about dirt once it gets to turbine blades and starts plugging the holes
The sand sucked into the engine normally goes into gas phase in the burner then solidifies into a glass type material as it hits the HPT inlet vanes and 1:st stg blades cooled leading edges and blocks the cooling air flow in certain ways, normally just around the hole openings. The salts works in a different way and its sulphur content gas phase goes to solid at lower temperatures normally found inside the 2:nd stage blade internal cooling channels, hence you need to corrosion protect the inside of HPT stg 2 or IPT blades to avoid corrosion induced cracking not visible by borescope inspection on its outside.
Engined are Type Certificated. The engine and its serial number is appended to the Aircraft Logbook in the equipment section. Engines are subject to service bulletins and AD notes just like the Airframe.
I don’t see that as relevant to my questions. Equipment lists and what is on what aircraft change all the time.
Engines are a bit one but computers etc also change.
@TW
Yea I agree. Service bulletins are released all the time…many for mundane things. There must have been something profound about this configuration change that required a re-cert. Even a new T1B by itself would not logically require a re-cert.
Thats because the Leap engines were failing with some cracked blades and losing some blades.
Hence the airworthiness authority’s slapped restrictions by shortened TBO or inspection.
To get back to the previous TBO GE had to find a fix and also provide replacement parts.
This is where the FAA/EASA approval was required to get the restrictions lifted .
This the lead theme in the story but GEs PR cleverly got the aviation media to concentrate on dust particles and the “allowing the engine to stay on wing longer, especially in hot and harsh environments.”
No mention the ‘longer’ was because a restriction was imposed because the engines were failing.
A classic snow job.
Just surprised Bjorn didnt see the ‘lipstick on the pig’ and run the real reasons first plus the new parts required and the PR second.
Missing all the stories about the soap opera at Boeing. Going through Boeing news withdrawal right now.
@John
You can only beat a dead horse so long with Boeing. Refreshing to talk real engineering and design issues for a change. Hard to get interested in tariffs and world politics.
Its not that Tariffs and world politics ae not interesting, but trying to herd it into a simple discussion on Tariffs is impossible. Its the politics (or worse) that drive all of that.
There re no answers on that subject. Its fluid, if it happens it can play out in so many ways and even total violations (and least tried) we won’t know till after (and exemptions I should add). When the center is irrational, you can’t have a rational discussion.
So a good tech discussion is a wonderful thing. Machinery does not play games. The Boeing pounders just repeat themselves over and over again, it gets boring. No insight or answers and opinions vs facts.
I would like Bjorn to respond but its almost like the upgrade is more a Trent TEN situation as has been noted that so much changed it needs a new cert.
Curiou what the cross over is. Trent TEN was 75% different. What is the cam over point? 51%?
I’m guessing (and it is a pure guess!) that there’s changes that are “certification neutral”, and others that are not. If CFM’s changes haven’t altered anything of note to any consequential extent, other than the engine now lasts longer and has a modified Bill of Materials, maybe it’s acceptable to simply demonstrate that “equivlence”.
Whereas if there’s been major work done on the design (such as Trent TEN, evidently), it’s not equivalent.
If so, then it’d not be a percentage change, it’d be more like “what’s changed?”. By the sounds of it, something as simple as changing the shape of the spinner cover in the centre of the fan could have significant consequences on the engine’s certification. That’d be <1% change in the design, but could result in a lot of re-cert testing w.r.t. ice, dust, etc.
Good catch TW
“upgrade is more a Trent TEN situation as has been noted that so much changed it needs a new cert.”
That seems to be the case , they ARE fixing the lack of durability
CHICAGO, Dec 6 (Reuters) – Jet engine maker CFM International said on Friday aviation regulators in the United States and Europe have certified a “more durable” high-pressure turbine kit for its LEAP-1A engines that power the narrowbody jets of Airbus (AIR.PA), opens new tab.
LEAP engines have been facing durability issues in regions with hotter and harsh environments, like the Middle East and Asia, causing frustration among airlines.
Its the usual GE style of fixing their engine issues as an ‘upgrade’ and fed to the tame aviation media.
Pratt and Rolls never get their problem fixes treated like that
Edit: This gives more detail of the ‘kit’ ie rebuild parts for existing engines
“The U.S. Federal Aviation Administration (FAA) and the European Union Aviation Safety Agency (EASA) today certified the upgraded High Pressure Turbine (HPT) hardware durability kit for the CFM LEAP-1A engines powering the Airbus A320neo family aircraft. The durability kit is designed to increase on-wing time, especially in hot and harsh environments, and includes the HPT Stage 1 blade, Stage 1 nozzle and front inboard nozzle mount.”
https://www.aeroflap.com.br/en/FAA-and-EASA-Certify-CFM-Leap-HPT-Hardware/
You don’t read LNA? We reported this on Dec. 10.
https://leehamnews.com/2024/12/10/cfm-gets-faa-and-easa-certification-for-a-more-robust-leap-1a-turbine/
Yes. But it wasnt a durability upgrade as a normal process for the new engines coming down the line
This happened first
“Cracks in the high-pressure turbine (HPT) rotor stage 1 blades of CFM International Leap-1A engines have been reported in engines operated in the Middle East and North Africa (MENA) region. The cracks are caused by a buildup of dust that accelerates deterioration of the blades.”
and
https://www.flightglobal.com/safety/hpt-turbine-blade-loss-behind-leap-1a-failure-on-indigo-a321neo/159847.article
The parts on existing engines are being replaced as they are ‘faulty’
This is entirely the same as the RR Trent issues
This is Airnz dreamliners
‘In each incident, a turbine blade in the engine’s intermediate-pressure turbine (IPT) fractured and broke off due to corrosion fatigue cracking caused by a combination of blade design or construction, engine operation and contaminants in the air.”
Im pretty sure the Leap engines cracks and blade loss barely registers , while each time a RR Trent has the same issues it gets onto the main media.
GE has done a great selling job in this fix for their faulty Leap engines by promoting the sizzle of the ‘dust ingestion ring ‘ while covering the sausage that the major parts affected have to be replaced
Im almost expecting that Bloomberg has an exclusive on this story ..maybe to come ?
I am going with Duke on this one with a adder.
Airbus kept the A350 coat issue hidden. And its not just an application bust, though that was the first change. Then they changed the system.
RR kept the XWB 97 issue under wraps, it came out of Emirates as I recall complaining on the short on wing time.
They all do it.
P&W got nailed from the get go. For all the changes it did not have to undergo certification. Something to think about in how much the LEAP changed to need that.
Trans
BA kept its MCAS hidden, resulting in the crashes of two 737 MAX 8 and the loss of 346 lives.
The quality of the 787 was so bad that BCA had to yank eight aircraft from service due to structural issues.
Pedro:
And the Ford kept the Pinto gas tank issue hidden for years.
Obviously you got a piece of wood to whittle and are blinded to the posting and what it means.
“Engine mfgs make changes all the time to the engines. I have not seen that they were certified as such.”
??? What the hack?
Moon landings are fake because I were not there to see them myself??
@Pedro
The types of changes that nobody here’s about are routine matters like part obsolescence, cost reduction efforts or forging changes.
Sometimes changes in suppliers.
Usually a couple times a year there might be a whole suite of upgrades to a BOM. You only hear about the changes to address major safety or durability issues
GE and their coating process on the GenX shaft for the 787 is classic.
https://aerossurance.com/safety-management/b787-genx-fan-shaft-failure/
They used one process for the hand built unit, then when they industrialized the GenX build, they used a different shaft coating process.
That lead to the famous incident of shucking the engine out the back.
@Pedro
First time I read about that one. But that’s another good example of why configuration changes. I’m not going to look it up, but guess ing GE was forced into a new coating due to environmental regulations that meant they could no longer use lead. Also aware that Sermetel coating is under the same pending restrictions. Did a great job for anti corrosion and the replacements are just not as good
Part of it was a Lead free product.
The two goops used and one or the other was whacky.
There should be one process and procedure not a you can do one or the other.
And why a lead product would have been used in the first place, but its a great example of the confusion of hand build and then a more disciplined (or should be) of production and consistency.
“First time I read about that one. ”
understandable.
its been exorcised from the GenX WP page 🙂
Another case in point was the PW seal change that was a huge failure, very quick to fail and therefore dangerous.
How you can mess up some basic as a seal? I do not know.
I saw in in automotive one time (it may have happened many times but this I saw in person).
I was asked to fix the issue, but it was warranty and a mistake on my part meant issues.
I was right for the wrong reason. The seal had been changed from a design of a lot of years. The shop that did the work thought by serial number it was older seal and no issue. But did not know it was the new seal until they had it apart.
They beat on GM for two weeks before a new type seal was located. In that situation it was why would you change a seal that had worked for 20 years or more? No answer to that, maybe a new seal engineer that wanted to prove how good he was?
But PW clearly did little testing, just assumed it was better and they paid for it.
One of my objections to the engine build business AHJ oversight. It should mandate testing. And then only select Airlines should be allowed to deploy it until it has time on it. IE where there are lots of diversions.
You push the odds and one day you will get a dual engine failure on a twin and then its luck of the draw in survival. The 767 that had fuel calc and two engines out in Candada was beyond lucky in outcome.
@TW
This was an expample of a seal that was having “issues” so in a rush to fix this fleet risk the medicine was worse than the disease. It was released without proper testing.
The temporary mitigation was to shut down the fleet to put it back to the orginal configuration until a final fix could validate.
The term “seal” can be tossed around liberally. This was a knife edge seal on the Aft Hub, not a rubber gasket.
All the same, there is a fine line between rushing out a fix and doing the due dilligence to ensure it is at least not making the problem worse. It is not a defense, but if you see a slower and more methodical process to fixing fleet issues that is not necessarily a terrible thing.
Agreed.
Any time you deal in a dicey area like a seal (and yes it was knife edge not rubber) you have to test it.
Seals seem simple and the complexity of what they do is amazing.
This is another aspect. You would have thought the 1000 had all the upgrades it needed but it and the 7000 are still getting major ones.
https://www.flightglobal.com/engines/rolls-royce-closes-on-us-certification-for-crucial-trent-1000-upgrade/161146.article
Note the EASA and FAA certification aspects.
P&W is looking better all the time!
Tough one for RR as the 1000 is no long built (replaced by the TEN if anyone orders the RR option).
@TW
The RR position on the B787 is cursed. There is nothing good that will ever come from this installation. It is a minority position on aicraft where GE/CFM owns the rest of Boeing.
The investment to ever really fix the durability problem simply is not worth it.
@Casey:
I am more a cause and affect guy. For whatever reasons, they were amazingly inept on the Trent 1000, maybe saw it as an easy program and put their 2nd rank people on it?
GE was just starting to get its game sorted for large two spool engines. Not that they did not have some problems but miner enough they got ahead and RR kept falling further behind.
RR has to meet its obligations, so they are fixing the Trent 1000 issues despite it being a fixed number now. Anyone who takes a new build 787 will get the Trent 10. Not as good as GE for On Wing, efficiency, cost of overhaul but not breaking when it should not. The big guys including BA gave up and went with GE.
The Trent 10 was the path to the Trent 7000 which is why the A330NEO got held up. I think once they went down that plan path, to change it meant more delay.
You see the Trent 7000 gets fixes sooner, because problems with the 1000 went into the TEN and those in turn went into the 7000. Having the exclusive on the A330NEO lets Airbus sell the 7000 with no competition so long term it may break even.
Our reference was to a Dead Alaska Native under our hangar!
It really was FedEx fault, they used an Oklahoma Engineering firm mixed with a contract structure that used Free Money from the State of Alaska and as such, State was the Build Oversight. The Oakies were oil field people from the valves they used, no idea of arctic conditions and the State was not setup for Supervise and FedEx could not change things.
Its one reason I am sour on Free Lunch money. State of Alaska spent 10s of billions on projects that failed.
So, we are in a Seismic 4 zone. That means we can get 9.0 Earthquakes (fortunately only ever few hundred years but we had a 7.3 almost under the city from a typo they did not know we got (Intra Slab) a few years back that was terrifying and I am not ashamed to say that.
So builds are to Seismic 4 Standards. The first hangar structure was specified to that. But the huge gap in the program, no one asked for proof that the welds met Seismic 4 requirements (the entire weld joints on the Alaska Pipeline had a weld Xray taken to proved those welds were good and we have never had a weld break)
The had the front section up and two bays when an inspector saw a but cut off (some parts were longer and a custom fit) and it looked wrong. He took it in and the Xray on it said only 80% of required weld. They tried to fix it, laid all the frames on the ramp, covered with visqueen and cutting out and welding back.
I cam to work one day and it was dark. I told the manager something was going on as they alwyas had lights and welding and cutting you cold sea through the whole tent city.
The Steel Package supplier had just quit. Cost less to give up the bond.
When the Structure Supplier was asked why they did not meet the welding spec, it was classic.
You can engineer these things or you can go brute force. We do brute force. As you had no requirement for Xray, we did not Xray, if you want Xray you have to write than into the contract, price goes up and then the people that do engineered lattice work structures win. Hard to argue with them.
It seems RR went down a similar patch. Eventually you wind up with the train wreck. What they would have done if the whole thing was up and they found out how bad the welds were (they went as low as 40% of spec so what the inspector found was the best they had done)
I think it would have held up to any quake. Solid welding seams one end to the other. But the only way they can control quality is to have those specs and it sure did not meet them.
The sold the original hangar Package to a company building a hangar in an area that had a low enough Seismic Spec to be fine.
They got an engineered package in on a 2nd bid but it took them 6 months to get it (probably be two years now)
I saw a lot of that mechanical systems area go off the rails but that was the worst and many of the systems had issues.
In the end they spent something like another 7 million to fix the heating and air compressor systems that were the worst (and they got rid of all those weird you have to lube them oil field valves – many of which we could not close)
Earthquakes are not in the post.
Hamilton
@Scott:
I was trying to frame how a project can get off track and that while I am not a Jet engine guy of any type, I have been involved in how things can and do go off track. That was a 25 million dollar project so we are not talking peanuts. Overall I was responsible for mechanical systems and various expansions into the 150 million dollar or better.
There is no intent to discuss AK Earthquakes which framed why a major part of a build program went into the pits.
Its bad management that is the root cause of all of it. Bad choices on the program lead people who then devolve into MAX like meltdowns.
That T1000 is only an ‘upgrade’ because it was failing ! In order to get TBO restrictions removed its needs sign off and of course replacement part kits supplied . Just like GE Leap
Flight paywall means details arent shown in your link. Maybe paste some
small relevant bits ?
I want to make it clear that this is not an attack on RR. They clearly do and have problems.
Flip to that is the Trent 700 program that went on to be the main choice for the A330. RR did a great job in upgrading the RB211 into a good and then great engine in the form of the Trent 700.
I have worked with mfgs that thought they were the Ultimate in their field. RR was one of those. I don’t have an issue with proud but when they get elitist, yea that bugs me. Caterpillar in my world was the same. They thought their engine were just fantastic and others were mediocre. Cat was good with its own failures, Cummins, Perkins etc built and build great engines equal and in some cases better than Cat.
RR has lost something. Its very Boeing like in that regard. They may get it back but clearly their current programs are not what the Trent 700 was.
Can they get it back? CFM has that question and PW seems to have solved their issue that were very public vs GE.
There are three vectors involved here:
1: GE has press protection. any issue with their product will kick of a shit storm campaign on RR and its products.
This is a long standing practice afaics.
2: I have no idea what part of RR inner mechanics lead into the blade deterioration trap. share holders trying the “leeching Boeing” method?
3: The attack on RR’s business model by essentially uneducated “analyst” was answered (low ingenuity) by reflexive job cuts.
( which then aggravated coping with the quality issues by extending reaction times … )
Overall it is not wrong to look for the symptoms in corporate entities that follow the Boeing pattern of potential to profits conversion.
I have to agree, its all Boeing fault and nothing to do with how RR selected the CEO
And in this case its CFM not GE, though I am sure they run the joint company.
@All
I tread lightly here because if people read enough of my comments they can generally figure out where I come from so I go to great pains to only discuss things in the public realm.
The engine community is a small one and everyone watches each other. Institutional pride can drive some design changes, many times to a fault. Every company around long enough has horror shows of bad decisions, many of them self-inflicted due to institutional amnesia of prior bad decision. Some bad decisions are due to a cuthroat business where you are playing at the limits of techonology. There is no historical modeling even available for some technologies. You really do not know until an engine is in revenue service to see all of the warts. The toughest part of the engine business is the profoundly consequential effects of a fundamentally bad design. These business cases last decades; they are longer even than the aircrames themselves as those revenues are realized at time of sale while engines have to wait for decades of aftermarket revenue. RR mades some very bad decision on the B787 to the point that anything short of a new engine will fix it. RR will not be making that investment…and its hard to blame them given their current market position.
We are all better off with a healthy RR. We need companies willing to make disruptive change. I look at the AIB/ BA setup and I see no competition now…and that is bad for everyone. You will be lucky to see a new aircraft by 2040. That is 15 years away and I really believe it.
The Trent TEN is a new engine by any standards.
It did not fix all Trent 1000 issues because it happened to carry over the very deep core and that was the bald crack resonance they were missing.
It got approved with some waivers for environmental busts in some flight modes that had to be fixed.
Only time will tell on on wing time and reliability once all the fixes are in place, but it has not matched the GenX for SFC.
I believe it finally met the contract specs but GE has also been improving the GenX and it is beyond contract specs now.
One of the not understood aspects of a Three spool is it more costly to overhaul. So it needs to have better SFC and on wing time to overcome that downside.
A330NEO owners are not likely getting the optimal engine so 787 vs A330 (granted its a bit hard to direct compare) has some disadvantages and if they don’t get the on wing time up, the a long term negative.
What I admire about the PW1000 is they got the gear system right. Whey they failed in those other areas is also a huge ?. It not like the don’t build military engines into the harshest use possible, let alone their various other offerings in business jets.
Safran wnet a route with the Silvercrest engine that had been determined by others to be a bad dead end and that was a bust.
The link it to a modern era cycle engine but it was an odd choice (V-4 would have been a very good configuration) and then they quit just as they had ironed out the issues.
https://www.youtube.com/watch?v=lTfH6ahsMxg
In some ways it mirrors the GTF in a lot of the failures were non engine, aka ignition which should be a slam dunk build and clutch.
Subset is that when they go0t a lead they hammered it hard and did not back off.
So much of mfg and projects is they know better and proceed down a bad path anyway.
@TW
There are some other factors that get lost too especially on single aisle. The entire market up-gaged. The incredible intervals on older engines were driven in part by A319ceo and A320ceo installations where the internals were fundamentally set by LLP life. You could set your watch to those shop visits It’s 50/50 on A320/A321 now.
Then there are some true environmental factors that are shockingly worse than they were 20 years ago. Do a google search on the 100 dirtiest cities on earth and you will find a high concentration in India. Unfortunately engines are not designed with the most toxic environment as a baseline.
And then there is another factor…manufacturing costs. Better parts can be made by using more exotic materials…but at a stiff price with an unproven supply chain. You really don’t want to base production on boutique companies that have not made product at volume.
Thanks for that TW.
However you have a misunderstanding here
‘One of the not understood aspects of a Three spool is it more costly to overhaul. So it needs to have better SFC and on wing time to overcome that downside.”
Its lighter and shorter for one
A secondly the more maintenance doesnt add up, as in number of stages add up. Remember the front fan is its own stage in a RR T1000
So for GEnx-1B we have
1Fan/4 stage LPC
10 stages HPC
and in the turbine section
2 stage HPT
7 stage LPT
That makes 14 comp stages (excl Fan) and 9 turbine stages
For RR T1000
1 Fan stage
8 IPC stages
6 HPC stages
and turbine
1 stage HPT
1 stage IPT
6 stage LPT
so thats 14 comp stages ( excl Fan) and 8 Turb stages
The blade counts ( roughly) are the critical maintenance item
and its the GEnx that has more !
Merry Xmas
Happy Holidays to All:
I am not an RR repair guy or center. I have read about the engines.
The Maint cost has to do with the 3 spool more complex design. Makes sense to me.
And with the RB211, it worked in that it had better SFC and on wing time (shorter engine has advantages). Per the reading, it cost more to overhaul but was worth it as you got more out of the engine. Longer on wing time pays off as you reduce the times it has to go into the shop.
Good for RR and well played.
But, they also got convinced that 3 Spool would always be superior and GE took a long time to do it, but the GenX proved that you could design a two spool with better SFC and as good on wing time.
That truly is a tough one as all your data is focused on how good your stuff was and better than the lower cost competition but made up for it.
Most if not all tech companies run into that challenge.
It bit RR with the Trent 1000 and then for unfathomable reason , they did not recognize their harmonic problem and passed that into the TEN which means into the 7000 as well.
I assume they thought they could salvage their engine position on the 787 with the TEN and they needed it for the 7000. It did not work on the 787 and Airbus is stuck with the 7000 on the A330NEO. Its part of the reason you won’t see an A330NEO MRT in US Service, no US optional engine and the cost to make one…………….
No one is going to say how well the 7000 is doing, they are stuck with it. Clearly RR is going to make it work as well as possible so they likely will get a decent engine.
GE gets called on their issues and its good they are. Worse by far is going under the Radar and a problem engine.
No idea what the contractual agreements with Boeing and RR are (pun). But RR has lost major top tier past customers over it. Likely they want out but can’t get out for current contract or future possibles or both.
@Casey:
CFM-56 was really great on the NG as well. Not a brilliant engine but they worked it into a good and reliable one. How many of the decision makers are still in place that saw the issues with the early ones?
My poster Child for bad decisions was International Harvester on their diesels emissions approach. Maybe Navistar, not sure who they are these days.
Their top engineer insisted that you did not need EGR when even Cat was using it. Right up to the deadline, living on old emissions credits and then, no, we can’t do it. So, I see that, its just that its so blatant at times though I don’t think RR had that. When your experience and business model is all 3 spool, you think 3 spool is always going to be the answer.
I seriously doubt GE knew they would outdo RR.
But how a company that makes big jet engines missed harmonics is baffling to say the least. That is IH class dropping the ball.
Where CFM gets all its stuff from I am not in the know, but they did go exotics for the LEAP to get parity with PW1000. PW has much easier patch to improvements.
I am convinced that is why CFM had to do such a massive upgrade. They could not fix their issues and well done on keeping them on the low down.
That has got to have a lot of MX ops thinking, you dogs you. PW may well get a significant uptick in winning bids though CFM has MAX locked and if they can only get Boeing production up! Call it 2/3 of the market without trying.
What also should be kept in mind is the A220 market and while its small, its been out productioning the MAX for a while now! (I expect the MAX will get back to 20 a month pretty quickly)
“The blade counts ( roughly) are the critical maintenance item and its the GEnx that has more !”
Additionally the intermediate spool can be more compact due to higher rpm.
For the 2spool engine the LP spool rpm is forced by the fan ( size, tip speed limit ). LP stages need to have bigger diameter and more and longer blades.
The GTF uses the gear reduction to get at that issue.
LP spool has similar rpm to the HP spool. ( and significantly reduces blade count )
3 spool and GTF are two solutions to the near same problem.
@TW
If we are going down the rabbit hole of future engine designs…
1) Forget 3-spool engines, you have probably seen your last 2-spool as well; they will all go to some form of gear. Moreover, the gear ratio will increase and likely incorporate planetary gears
2) Ceramic matrix for all in the hot section
3) Composite fan blades
4) 2 stage HPTs (CFM already went there)
Maybe points
1) Battery assisted (hybrid)
2) Unducted (glorified prop)
3) My personal fav if it can ever be figured out…variable gear ratio…e.g, a transmission instead of a fixed ratio allowing operator to throw it into high gear during cruise altitude
Feel free to add more
Unless I am off my rocker, a GTF is a two spool design!
RR insists the Ultra is a 2.5 spool design (we have to keep that stiff upper PR lips)
I just find it interesting that you can have (or had) 3 different approaches to the same issue and 3 different takes (three spool and exotics, two spool and exotics or a GTF with not so much exotics)
I don’t think for a second that two spools and GTF will go away anytime soon.
RISE is still a jet engine though arguably 75% of the way to being a Turbo Prop.
At the heart they all suck, fire and blow.
@TW
I should clarify my earlier point. I do not think you will see a 2 spool “direct drive” again.
Agreed for LCA.
smaller stuff and fighters will continue two spool direct.
Rise is a gear drive as well which you expect from a Turbo Prop (grin). Granted its kind of a hermaphrodite half way between a jet engine and a TP.
As it has open blades I think its 2/3 of the way to the TP side.