A320neo start-up times

The hype was huge when the problem around longer start-up times of the PW1100G-JM went public. Indigo stated that the ~2min. extra time that it took to start up the engines would threaten their Business model as a low cost carrier with high utilization and short turn around times between flights. As I showed in an earlier post this was not very plausible from the beginning. But at airports with tight infrastructure (Frankfurt comes to my mind) it could cause some headache - more for the airport than for the individual airline though - as, if one aircraft blocks the way to the gates as it has to wait until the engines are started, other aircraft have to wait.
Believing what Airbus, P&W and Lufthansa said recently the problem is largely gone now.
Now we can read in a report from airwaysmag about the first revenue flight onboard on the first Frontier A320neo that the that the competing LEAP-1A engine has a "noticeably long startup time". What that exactly means we don't know yet. There was nothing official about that yet, showing once again that the PR Folks at GE, CFM and Safran are doing a much better job than those at P&W.
But maybe someone should tell Qatar Airways CEO Al Akbar about it as the LEAP-1B should "suffer" the same problem before he confirms his order for the B737MAX. Or maybe he already counts on compensations...?

The CFM LEAP-1B discussion

Last week, after the first flight of the LEAP-1B on the GE Flying Testbed, Aviation Week had a story about the LEAP engine family and the alleged performance shortfall, in particular the -1B for the B737MAX. Leeham then also had a short article, stating that the SFC shortfall, first reported by Aspire Aviation of 4-5% was only measured in one engine, where “tolerances” (i.e. gaps and, in particular radial tip clearances) where intentionally opened to test a deteriorated engine.

This kind of testing is new to me, I never heard that these kind of tests were done. In the end it is very expensive to build a test engine solely to measure the performance with so called “end of life ”clearances”. Normally the clearances in the engine are constantly measured so you get a relation between the change of the clearances due to wear and rub ins and the change of the performance (both fuel burn and compressor stability).

To build in intentionally larger tip clearances makes sense only for the compressors to test compressor stability. And if these tests showed a SFC shortfall of 4-5% (I now heard 5%) then either the performance retention of the LEAP engine is very bad or there indeed is a performance shortfall as the effect of larger tip clearance should not lead to a loss in SFC larger than 2%.

Now CFM always mad big  noise about the good performance retention the LEAP engine family would have, in particular compared to the P&W GTF Family. One could ask: how do they want to know that? And I think, neither CFM nor P&W nor anybody else can know today and will know until real life data is available. With “real life data” I mean data that will come out of the field once airlines really fly the aircraft and engines for some time.

So we don’t know for sure how much of the (obviously measured) 4-5% are attributable to a new and with production tip clearances build engine. But CFM’s argumentation does not add up to the point where they would meet not only their own expectations. To meet the own pretest prediction within 0.5% does not mean a whole lot to the outside world until you know where the prediction was relative to specification, i.e. relative to the target SFC where the B737MAX would meet 14% fuel burn reduction vs. the B737NG.

CFM LEAP-1B missing SFC

The revelation by Aspire Aviation about the performance shortfalls of the CFM LEAP engine family did not came totally unexpected. Rumours have been around for a long time. But the severity of the shortfall in the LEAP-1B engine is somewhat shocking, at least for Boeing customers. The shortfall of 2% in the case of the LEAP-1A is relatively unspectacular: the shortfalls of recent engines at EIS like the GEnx and the Trent 1000 were higher. A shortfall of 2% can be corrected with a suitable performance improvement program (PIP), but a

B737MAX - the next diameter!

UPDATE: Jon Ostrower reports that the exact diameter will be 69.4" and that the engine will also get smaller core size. I have not seen the article myself as I do not have a WSJ subscription, but Scott Hamilton has an update on the story, too.
Scott writes that a smaller core fits better under the wing. Well, yes and no - the core, meaning the HPC and HPT are physically smaller, but as the worksplit between the high and low spool changes, the LPT has to do more work now - and at the same time needs to run slower because of the larger fan. So the diameter of the LPT has to move out as described earlier. And there could really be a need for an additional LPT stage with the higher loading of the LPT. Only if the efficiency of the LPT can be kept constant the smaller core size and higher bypass ratio will do any good for SFC and  fuelburn. Temperatures in the core will rise anyway - what this means for maintenance costs customers will see only a few years after putting the engine in service.

It is becoming a real saga: the fan diameter of the B737MAX LEAP-1B engine. Now we are at 70", compared to the 61" of the CFM56-7BE and the last announced 68.4". Read the story at Leeham News here:
Sorry - but, but for me Boeing is loosing credit with every change that is announced (or, as in this case, reported by a credible source). For months Boeing now said "Bigger is not better", defending the B737MAX and the LEAP-1B against the A320neo and the LEAP-1A/PW1100G with their considerably larger fan sizes.
So, is the larger 70" fan just for optical reasons? Just a joke, of course...
A larger fan needs to run slower to keep the efficiency high - or in other words: the tip speed needs to be the same as it was before. But this means that the LPT also needs a larger diameter to keep it's efficiency - or the LPT needs an additional stage. If this is beneficial in the end? It looks like Boeing looks only at fuel burn now, not at overall operating costs in the first place. I eagerly wait for the next press release from Boeing regarding MAX.

Even more doubts about B737MAX

I obtained a very interesting article from "Airline Economics", a publication from Aviation News. As it is a subscriber only magazine, I cannot upload the full article, but I will quote some interesting statements of the story called "A question of circumstance":

1. Regarding the engine competition on the A320neo between the GTF and the LEAP-1A: "The end result is that you've got a really big gap between a P&W Neo and a CFMi Neo." To clarify: the gap is in favor of the P&W GTF and Airline Economics is quoting an senior industry expert here, who expects the LEAP to have a 4% disadvantage (what in my eyes is maybe a little bit too much).
2. Regarding engine competition in the marketplace: "Airline Economics learned early last year that

GTF for B737MAX?

Rumors are spilling over and over since the ISTAT Americas conference in March that Boeing is seriously looking at the P&W GTF as a second engine option in addition to the LEAP-1B for the B737MAX. Aspire Aviation has a long article about the ongoing optimisation of the MAX here and Scott Hamilton is quoted in an article by the New Mexico Business Weekly here. A reason for these rumors seems to be the lack of confirmed orders for the MAX so far. There are only three customers who have ordered the MAX, all others only delivered commitments to the Boeing Headquarter so far. Sure, the year is long, so there is enough time for Boeing to convert the commitments to firm and credible orders, especially as Boeing might be keen to make a similar splash with the MAX at Farnborough as Airbus did with the Neo at Le Bourget last year. But as now there are these rumors about a possible second engine, the committed customers might want to wait and see if there is some truth behind them. So firming up the commitments before there is a final word from Boeing (or P&WA) in either way might be a challenge.
Scott Hamilton expects a decision in the next months - that could also coincide with Farnborough...

Definitive LEAP1-B fan diameter!(?)

Yesterday at the ISTAT Americas conference Mike Bair from Boeing revealed that the LEAP-1B fan diameter for the B737MAX now stands at 68.4". When Boeing and CFM for the first time officially announced a fan diameter for the LEAP1-B in November 2011 (Press Release), it was 68", 7" more than the fan diameter of the CFM56-7BE of the current B737NG.
In the meantime there were news in different but reliable media (LeehamNews, aspire aviation) that the diameter went up to 68 3/4" or 68.5". So now it is 68.4" - what does that tell us?

1. Size matters - although Boeing denies that. Well, of course there is a sweet spot for every aircraft/engine combination, as Scott Hamilton writes in a recent column, so you can't go everywhere with fan size. But apparently CFM still tries to maximize the fan diameter of the LEAP-1B so it just fits under the wing and to get the best possible fuel burn for the aircraft. That means that 68" is not the sweet spot, but that is is somewhere higher.
2. It means that the definition of the engine is probably still not finished yet. If the fan size changes, this potentially changes everything else - at least if you want to maximize efficiency of the whole engine. In turn that means that there is still a lot work for Boeing to define to pylon and the pylon/wing interface.

So stay tuned for the next MAX fan diameter...

Airbus: GTF better than LEAP...

I obtained an interesting note from Forecast International, itself claiming to be the "Leading Provider of Aerospace, Defense, Electronics and Power Systems Intelligence. Here it is:

Ryanair and B737MAX

Not often I tend to agree with the outspoken Ryanair CEO Michael O´Leary, nicknamed by the twitter community with @MichaelOhReally. But when he recently talked about the B737 MAX, I had to agree with him. He said that he has been impressed by the fuel burn improvement the A320neo promises to deliver, but he is not impressed by the B737 MAX and said that the fuel born improvement is inferior.
Particularly he fears that the heavier CFM LEAP-1B engines and the subsequent heavier airframe will offset the better SFC, when compared to the CFM56-7B(E).
Meanwhile I had the opportunity to read the latest

Norwegian goes the American way...

That was a surprise this morning - it was long rumored that Norwegian is one of the airlines that already committed for the B737MAX (100 firm orders plus 100 purchase rights in addition to a follow-on order for 200 B737-800NG), in that case the -8 model. But that they also would order the A320neo (MoU for 100 aircraft plus 50 purchase rights) could not have been expected.
There are two possible explanations that come to my mind as reasons for that decisions to go away from a single-type fleet:

1. They went the AA way (of negotiating), meaning they negotiated with both Airbus and Boeing until they got a deal from both they could not resist to close them both.
2. Their anticipated growth is too large that one of the OEM's could deliver aircraft fast enough to satisfy that growth.

On the other hand it is a little bit discussable if a mixed fleet of B737-800NG and B737MAX-8 would be a single-fleet type anyway. The engines (CFM56-7BE and LEAP-1B) do not have anything in common and Boeing itself talks about 85% commonality between the NG and the MAX. So Norwegian would have had a two-type fleet anyway until the last -800NG would have been phased out. Now that Norwegian gets aircraft from both Airbus and Boeing the last -800NG will be phased out earlier so that the (at that scale) marginally higher costs through having a two-type fleet will be (probably) more than offset by the lower fuel costs.

The next interesting question will be the engine choice for the A320neo. Although the selection of the LEAP-1A to complement the LEAP-1B on the MAX-8 fleet would be the most logical choice, they maybe also go the AA way and buy from both engine manufacturers, like AA did it recently for their A319 (CFM56) and A321 (V2500). So the PW1100G could come into play - the factsheet that Norwegian provided with their press release shows the fan diameter of the PW1100G (81"), but that does not necessarily say anything...

Embraer decides in favor of EJet's

Embraer decided to abandon plans for a new 5 abreast aircraft for now and instead opted to reengine to EJet's in the latter half of the decade - EIS could be in 2018. Given that Embraer could not do both at the same time - financially, but also due to manpower restrictions, as the KC-390 is in development also, this seems to be a wise decision.

Let us look at the timeline: in 2018 all new engines currently under development for the MRJ, CSeries, the A320neo, the B737MAX, the C919 and the MS-21 will be in service. Of course one could ask at least in case of the latter two if the EIS dates for these will stay where they are now. But Embraer will have a good idea how the engines - two versions of the LEAP (the C919 LEAP-1C will have the same turbo machinery as the A320neo LEAP-1A) and three types of the GTF (MRJ, CSeries and A320neo/MS-21) - are doing during development. An EIS in 2018 would probably mean an engine selection about 5 years earlier, around 2013, maybe 2014. By that time the PW1200G and PW1500G are flying at least on the respective aircraft prototypes and the first PW1100G engine should run on ground (the LEAP-1A seems to be a bit behind).

News about MAX

Jon Ostrower (Flightblogger)  and Scott Hamilton both are reporting about a presentation given by Boeing Commercial Airplanes CEO Jim Albaugh at Goldman Sachs.

ISTAT Europe 2011

For the second time I had the pleasure to join the european ISTAT (International Society for Transport Aircraft Trading) meeting, this time taking place in Barcelona, a wonderful city! Here are some thoughts about the conference...

A320neo
Last year the conference was "overshadowed"