Quoting kurtverbose (Reply 299): Probably a short flight given the fuel consumption.

Actually, it was about 2 hours longer then the GTF neo 1st flight... I guess that means the GTF is in trouble.  

Quoting mffoda (Reply 300): Actually, it was about 2 hours longer then the GTF neo 1st flight... I guess that means the GTF is in trouble.

This is how they did it.

Quoting kurtverbose (Reply 301): This is how they did it.

Those neo interiors suck!  

Some new discussion here:

LeapX Engine Performance On Track For 737 & A320 (by Roseflyer May 24 2015 in Civil Aviation)

from

http://finance.yahoo.com/news/boeing...8DZ3ExBHBvcwMzBHZ0aWQDBHNlYwNzcg--

The new answers are kind of not really answering the original rumour. It was never said that the LEAP was 4-5% off, it was said that there is a difference in performance between 1A and 1B. Nobody told us if the engine used for tolerance testing was a 1A or 1B, but considering the certification time line, the use of a 1B would be strange imho.

Quoting seahawk (Reply 304): Nobody told us if the engine used for tolerance testing was a 1A or 1B, but considering the certification time line, the use of a 1B would be strange imho.

The 1A was already (or just about ready to be) in flight test while the 1B was not. So perhaps they have already done it on the 1A or since the 1C is mechanically identical and farther along in testing, they might have done it on the 1C which would have negated the need to do it on the 1A.

So, IMO, the 1B being the test unit would not be strange.

But even then it still would not really answer the rumours that there is a difference in performance between A/C and B. This point has not really been answered by CFM in all responses they made.

Apart from that I think it would be a bit early, considering the rumour surfaced in March, so the test would have to be run earlier. Say early this year, late last year. That is about 6-8 months into 1B testing and before the first flight of the 1B.

http://www.flightglobal.com/news/art...ign-making-steady-progress-412838/

Bit reliability trouble for PW and another person confident in the performance of the engines

He adds that Airbus and P&W are addressing a "maturity issue" on the PW1100G, relating to a seal in the vicinity of the high-pressure compressor, some production batches of which have shown "slightly more deviations" during operation.

Evrard says that he is confident that both powerplant types will reach the fuel-burn levels promised by their manufacturers, pointing out that the airframer has yet to conduct detailed analysis on the Leap-1A performance because it "hasn't had enough experience in flight".

I am thinking Airbus knows after the first flight, as they will be monitoring fuel burn. I would tend to believe that the current LEAPs mounted are probably known to miss the fuel burn target, which means it is a waste of time to put energy into measuring them. CFM will probably have promised an improved version that should meet the target.

An update on the matter. The first CFM LEAP engine batch for both the A320neo and 737 MAX face (a significant) fuel burn penalty:

http://aeroturbopower.blogspot.com/2016 ... issue.html

KarelXWB wrote:

An update on the matter. The first CFM LEAP engine batch for both the A320neo and 737 MAX face (a significant) fuel burn penalty:

http://aeroturbopower.blogspot.com/2016 ... issue.html

That article implies that the issue may only affect early-build LEAP-1A engines and therefore only really impact early A320neo deliveries?

Per the article, CFM says they will have a fix in place by mid-2017 which means that the LEAP-1B might be "safe" in that deliveries for the MAX are not planned until then (and then only because Boeing is ahead of their testing and certification plan). The LPC "fix" is retrofittable, so if CFM can get it out by then, they might be able to apply it to the first tranche of MAX frames prior to their delivery to customers.

KarelXWB wrote:

An update on the matter. The first CFM LEAP engine batch for both the A320neo and 737 MAX face (a significant) fuel burn penalty:

http://aeroturbopower.blogspot.com/2016 ... issue.html

I'm not seeing where the fuel burn penalty is quantified, or even categorized as 'significant', and even where 'significant' is defined.

The main factual statement we see comes from the linked AIN article:

Last year CFM discovered the need to modify the LPC to improve stall margin. With the original engines, Boeing has to use suboptimum bleed schedules, leaving the bleeds open more than desired for the best possible fuel efficiency. “We want the bleeds closed for better fuel mileage,” explained Teal. “We could have certified and delivered these engines, but we wanted the best engines. So in the ones we’re flying now the bleeds are opened a little bit more than we desire, but when the final Block 2s come in and we get the final bleed schedules, and that will determine the final configuration.”

So Boeing is saying 'suboptimal', yet that gets reflected as 'significant'.

CFM only says this is a durability issue, not a fuel burn issue.

Lots of different kinds of spin going on here.

Maybe GE's PR department really is earning their paychecks.

Ref: http://www.ainonline.com/aviation-news/ ... s-schedule

Hasn't Airbus said CFM are on spec on fuel consumption? If so does that mean the HPC change will bring them ahead of spec?

kurtverbose wrote:

Hasn't Airbus said CFM are on spec on fuel consumption? If so does that mean the HPC change will bring them ahead of spec?

I believe it is the P&W GTF engine that is better than spec...though it is having in-service "teething" issues.

kurtverbose wrote:

Hasn't Airbus said CFM are on spec on fuel consumption? If so does that mean the HPC change will bring them ahead of spec?

AFAIK what Airbus have said is:

- The A320neo airframe is 150 kg lighter than the original spec
- The GTF fuel burn is better than expected

No official word on the LEAP engine yet.

KarelXWB wrote:

kurtverbose wrote:

Hasn't Airbus said CFM are on spec on fuel consumption? If so does that mean the HPC change will bring them ahead of spec?

AFAIK what Airbus have said is:

- The A320neo airframe is 150 kg lighter than the original spec
- The GTF fuel burn is better than expected

No official word on the LEAP engine yet.

What is Boeing saying?

Tangowhisky wrote:

What is Boeing saying?

That customers are pestering them for the GTF or at least the larger fan of the Leap1A going against better advice from Boeing.
http://leehamnews.com/2016/06/29/analys ... an-brexit/

WIederling wrote:

Tangowhisky wrote:

What is Boeing saying?

That customers are pestering them for the GTF or at least the larger fan of the Leap1A going against better advice from Boeing.
http://leehamnews.com/2016/06/29/analys ... an-brexit/

Content in the comments to the article should not be mistaken for content in the article itself.

Stitch wrote:

Content in the comments to the article should not be mistaken for content in the article itself.

It's even worse, it's speculation by an anonymous poster will well known biases and precious little connection to the aviation industry being made in the comment section of a blog!

Revelation wrote:

Stitch wrote:

Content in the comments to the article should not be mistaken for content in the article itself.

It's even worse, it's speculation by an anonymous poster will well known biases and precious little connection to the aviation industry being made in the comment section of a blog!

hohah!

And worseness gets a further liftup from "Keesje" being the poster that I cited.

But it was just too well said to leave it unmentioned. ( ... and I'd also like to opine that it probably is a perfect reflection on the Boeing inside nitty gritty.)

Last I heard the low compressor issue will be fixed in 2017. First 737MAXs expected to be delivered with the fix. Everything I'm hearing is the low compressor fix resolves the fuel burn issue. Only the first 50 to 75 NEOs, by my estimate, will be delivered with sub-standard engines. As a Pratt fan, I'll like to make noise about this, but it is an issue with a known fix (better matching of Low and High compressor profile factors) and limited impact. While a low compressor changeout isn't cheap (oh.. $300k per engine or so assuming zero recycled parts, less if re-bladed).

https://www.flightglobal.com/news/artic ... in-424985/

Lightsaber

lightsaber wrote:

Only the first 50 to 75 NEOs, by my estimate, will be delivered with sub-standard engines.

And those customers will be compensated by CFM.

Is the interfacing issue then common to both the Leap1A and the Leap1B sub model?
( does this indicate that the differences between both types are not that large ( on level with the
GEnX 1B / 2B "span" ? )

A range of posters told us previously that the MAX engine is a completely different animal

WIederling wrote:

Is the interfacing issue then common to both the Leap1A and the Leap1B sub model?
( does this indicate that the differences between both types are not that large ( on level with the
GEnX 1B / 2B "span" ? )

A range of posters told us previously that the MAX engine is a completely different animal

The LEAP-1B has far fewer low turbine stages (5 vs. 7). Now partially due to a 9:1 (vs. 11:1) bypass ratio (I estimate that reduces the required low turbine stage count to 6).
The engine is a bit low turbine performance on the -1B. So yes, it is a different animal. But higher low spool RPM helps. It helps a lot. But it also means the low compressor does more work (requires more horsepower). That helps engine efficiency... I just do not see how 5 low turbine stages will work at that low of a mach#. (The PW1100G works with 3 low turbine stages as the turbine is at a far more optimal Mach #.)

But the basic concept is similar. What changes is the low spool RPM is far more aggressive in the -1B.

Lightsaber

Lightsaber, thank you for the good explanation.

Still open for my understanding: why do 1B and 1A seem to show the same mismatch?
Was there some projected advanced feature or other removed/reigned in
from the HP spool creating that mismatch late in the process?

LPC stall margin shortage is usually caused by the high spool deficiency, which elevates the LPC operating line. Re-blading will fix stall margin. I don't see a path to fix fuel burn, unless the LPC design missed the original stall line requirements, which is very rare for conventional (low speed) LPC.

lightsaber wrote:

[...]Everything I'm hearing is the low compressor fix resolves the fuel burn issue.[...]

You are are a highly respected and very trustworthy member of this board. In this particular case you are just the messenger who isn't responsible for the message itself. So I dare to say that I dont't believe this at all. By proposing a theoretical 737-10SUPRA/ÜBER, Boeing and CFM have frankly admitted that their current concept of a lazy compromise re-engining doesn't really work out well. Obviously they know that the forcefully degenerated "B" version of the LEAP engine will never ever catch up.

Kilopond wrote:

By proposing a theoretical 737-10SUPRA/ÜBER, Boeing and CFM have frankly admitted that their current concept of a lazy compromise re-engining doesn't really work out well. Obviously they know that the forcefully degenerated "B" version of the LEAP engine will never ever catch up.

It's the "A" version for the Airbus that has the issue. The "B" version for the Boeing will have the fix before it enters service with the 737MAX. So early A320neos with the CFM engine will be the "degenerated" one.

As for the 737-10, that plane - should it ever exist - needs more thrust than the "B" model can provide, which is why it would get the "A" or "C" model.

Stitch wrote:

Kilopond wrote:

By proposing a theoretical 737-10SUPRA/ÜBER, Boeing and CFM have frankly admitted that their current concept of a lazy compromise re-engining doesn't really work out well. Obviously they know that the forcefully degenerated "B" version of the LEAP engine will never ever catch up.

It's the "A" version for the Airbus that has the issue. The "B" version for the Boeing will have the fix before it enters service with the 737MAX. So early A320neos with the CFM engine will be the "degenerated" one.

As for the 737-10, that plane - should it ever exist - needs more thrust than the "B" model can provide, which is why it would get the "A" or "C" model.

I think he means the shrunken fan. They wouldn't have made the fan that small if there was room for a bigger, more efficient fan.

767333ER wrote:

I think he means the shrunken fan. They wouldn't have made the fan that small if there was room for a bigger, more efficient fan.

I'm sure they would, but the "B" version still looks to be a phenomenal success based on the number of MAX's ordered to date and I believe the "A" model is currently outselling PW's GTF on the A320neo so I don't see CFM crying about their current situation on both the A320 and the 737.

Stitch wrote:

767333ER wrote:

I think he means the shrunken fan. They wouldn't have made the fan that small if there was room for a bigger, more efficient fan.

I'm sure they would, but the "B" version still looks to be a phenomenal success based on the number of MAX's ordered to date and I believe the "A" model is currently outselling PW's GTF on the A320neo.

How much of those sales are sweetened by GECAS ( or other GE aligned ) financing and/or availability and/or Boeing going soft on pricing? All the little moves in recent times indicate that Boeing is desperate (or on the brink of desperation.)

A very popular endeavor to attribute decision outcomes to the "fits my agenda" but wrong metric.

WIederling wrote:

Stitch wrote:

767333ER wrote:

I think he means the shrunken fan. They wouldn't have made the fan that small if there was room for a bigger, more efficient fan.

I'm sure they would, but the "B" version still looks to be a phenomenal success based on the number of MAX's ordered to date and I believe the "A" model is currently outselling PW's GTF on the A320neo.

How much of those sales are sweetened by GECAS ( or other GE aligned ) financing and/or availability and/or Boeing going soft on pricing? All the little moves in recent times indicate that Boeing is desperate (or on the brink of desperation.)

A very popular endeavor to attribute decision outcomes to the "fits my agenda" but wrong metric.

Every vendor is leveraging their strengths as best as possible. For instance PW has been the sole supplier of engines for the F-22 and F-35 programs so should be getting lots of R&D on the cheap. GE has its partnership with CFM and the feed from all its widebody programs to leverage.

There's a lot of things that go into making a fine product, and the ability to finance these very expensive items is one of them.

WIederling wrote:

Stitch wrote:

How much of those sales are sweetened by GECAS ( or other GE aligned ) financing and/or availability and/or Boeing going soft on pricing? All the little moves in recent times indicate that Boeing is desperate (or on the brink of desperation.)

I'm rather skeptical that Boeing is incentivizing LEAP-1A sales on A320neos.

And you don't think Pratt is offering really strong warranty and maintenance contracts on their GTF deals to convince airlines to buy it considering how long it's taken Pratt do get it to market and it's still having in-service issues?

Stitch wrote:

I'm rather skeptical that Boeing is incentivizing LEAP-1A sales on A320neos.

And you don't think Pratt is offering really strong warranty and maintenance contracts on their GTF deals to convince airlines to buy it considering how long it's taken Pratt do get it to market and it's still having in-service issues?

Obviously Boeing will not bother to promote -1A sales. ( Interesting that you find it necessary
to produce this sophist statement from rather selective interpretation.)
Neither will they promote -1B sales.

They will promote 737 MAX sales ( moving Leap engines is just fall out due to sole source.)

Now Pratt can offer good warranty and maintainance conditions.
BUT the GE financing arm GECAS can offer financing for the engines _plus_ attached plane.

With financing often being a fickle thing for interested airlines
a strong incentive to buy A320 with Leap engines or Boeing 737MAX.

I came back to this thread to see if any *published* fuel burn numbers are out there? Has Airbus updated the A320NEO payload/range charts?

I'm very curious as to how the LEAP-1Bs low turbine performs. Is there enough added Mach # via the increased RPM to really allow for 2 fewer stages?
It is interesting in the 'flip' in advantages. Due to the PW800, most of the large business jets going forward will be Pratt powered with the obvious exception of the Global 7K/8K.

I'm a Pratt fan, so accept my bias. However, the nickel metals CFM is using are softer at temperature than they predicted. That will create a durability issue for moving parts and thus take away some of CFMs maintenance advantage (IMHO, CFM does a better specification definition which should result in improved initial maintenance costs, unless there is a design or material miss.) Note: I'm not talking strength of material but purely the hardness at temperature. Fatigue properties shouldn't be impacted; it is the wear (bearing) properties.

For the record, the 'startup issues' Pratt is having is due to its high spool being far more agressive in RPM than the LEAP-1A. With the LEAP-1B approaching Pratt (but not quite the same bearing speeds as the shafts are co-rotating instead of Pratt's counter rotating). I suspect Boeing is making sure CFM is learning everything they can about Pratt's teething issues.

Lightsaber


15 years ago, Pratt/UTC was trying to blunt the financing advantage GE/CFM had at the time. IMHO, they still have an advantage. Nothing unfair, just good business synergy.

Lightsaber

lightsaber wrote:

I'm very curious as to how the LEAP-1Bs low turbine performs. Is there enough added Mach # via the increased RPM to really allow for 2 fewer stages?

Lightsaber

Don't forget that the 1A and 1B are very different thrust requirements, based on airframer specification (we design to requirement of course). The 1A goes to 33k SL and 35-equivalent altitude bump (35A rating). The 1B goes to 28k. This is public domain data now, since both are certified. Hence the different LP system demand.