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March 2, 2024
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It’s a story that won’t die, and the buzz around ISTAT 2012 was that Boeing continues to consider offering the Pratt & Whitney GTF on the 737 MAX.Wall Street analysts were talking about it and FlightGlobal sat down with Steven Udvar-Hazy, considered the Godfather of leasing, at the ISTAT AGM in Arizona last month to talk about the MAX. Hazy urges Boeing to put the GTF on the 737, but doesn’t think it will happen.

We’re not so sure. 

We continue to hear that Boeing is seriously evaluating adding the GTF as an offering on the MAX, a move that would likely result in a battle royale between Boeing and GE/CFM, which has been the sole source engine provided since introduction of the 737 Classic in November 1984. The current model, the Next Gen, entered service in 1998.

It’s well known that GE/CFM has an exclusive supplier contract to power the 737, but it’s not as ironclad as one might think. In March 2011, Boeing’s Mike Bair, vice president of Advanced 737 Product Development for Boeing Commercial Airplanes, told AirInsight’s colleague Scott Hamilton that Boeing has the flexibility in the contract to put a competing engine on the 737 if the engine and commercial terms are superior to any engine offered by CFM. The CFM engine has to be “competitive,” and Boeing gets to define the term, Bair said then.

What does this mean? Neither Bair nor a spokeswoman will say, but those familiar with the situation believe that the GTF would have to provide an installed advantage over the CFM LEAP engine proposed for the MAX of somewhere between 3% and 5% in fuel burn.

It’s entirely possible that CFM could make up for any shortfall through economic support. Airbus’s John Leahy told a Credit Suisse conference on November 30 last year that the GTF on the A320neo provided about 1.5% better fuel economy than the LEAP.

It’s well known that CFM is much more aggressive than P&W in providing guarantees and economic concessions in GTF-LEAP competitions. It’s also well known within the industry that the International Aero Engines V2500 (of which P&W is now the dominate partner) is 1%-2% more fuel efficient than the CFM56 on the A320 family, particularly on the A321, and that CFM often makes up for this in commercial terms.

But would CFM be able to overcome a 3%-5% disadvantage to a MAX equipped with the GTF? To maintain a 45%-50% market share vis-à-vis the A320neo, this would be a very expensive proposition.

Boeing’s Bair, at the ISTAT conference, said the CFM LEAP (picture) will have a 68.4 inch diameter fan, which is within an optimal range of 3-4 inches of a “bucket”-like curve for optimization of the engine. CFM is designing a smaller core for the engine, essentially downsizing the one developed for the COMAC C919 and for the A320neo family. But the LEAP’s Low Pressure Turbine’s length and diameter remains a challenge for the low-slung 737 and weight is also said to be an issue.

Boeing has promised increased fuel efficiency of 10%-12% for the MAX vs the NextGen, but many sources inside Boeing say they are not there just yet. A combination of airframe and LEAP designs remain slightly short of this target today, though all believe Boeing and CFM will achieve this goal by the projected EIS in 2017—five long years away.

In the meantime, Boeing has converted fewer than 500 commitments to firm orders, with about 600 commitments remaining that have been announced by Boeing but not identified. Only Southwest Airlines, Lion Air and Norwegian Air Shuttle have announced conversion of their commitments to orders.

Aviation Capital Group announced it has committed to the airplane but so far has not converted to orders. American Airlines announced its plans to order the MAX, but the bankruptcy stalled any conversion (as is also true with American’s announcement to order the A320neo family).

Boeing and CFM will only say they have a contract with each other to provide power for the MAX. But we don’t think this story is over just yet.

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7 thoughts on “The Boeing 737 MAX and the GTF

  1. Interesting blog on a no doubt game changing topic..

    IMO two factors play a role too. CFM56’s earned a reputation you have to throw in bricks to get them into the shops. I’m surprised however how easy many assume this automatically to be the case for the yet to be build LEAP too. IMO there no base for this, just hope.

    Then it seems to me the GTF is build around innovative gearbox technology, changing the physics taking place inside the engine. The rest of the engines seem pretty conventional.

    CFM focussed the LEAP on optimizing temperatures, flows and pressures with new materials and shapes. I’m under the impression much of this technology could be applied by Pratt too, for the GTF. It might take years, RR, investments etc. Still, the further improvement potential of the GTF seems visible today.

    Less so for the LEAP, introducing geared technology might take a long time & result in an all new engine. It took Pratt 20+ yrs / lots of pain.

    I guess we might have to get used to the concept of mighty market leader GE playing catch up..

  2. Keesje, you are correct that GE is playing catch-up, but they are not gaining much ground. IMO it is pretty clear that the GE 136 was the development ground for the CMC technology that is ABSOLUTELY CRUCIAL to enabling the very high burner and turbine temperatures GE needs in the LEAP to be able to compete with the GTF whose gearbox allows the core to use “normal” temperatures and pressure ratios which are well within Pratt’s experience base. Keesje touches on this when he(she) says that the LEAP is not the same as the CFM56….it is nowhere close. With the shutoff of government funding for GE’s F136, the required advances in CMC technology will not materialize and the LEAP will probably miss its fuel burn and durability targets by a huge margin. GE has publicly stated that they will make their fuel savings targets either technically or commercially….which IMO means they know they can’t cut it technically without the CMCs. When a company states something so “in your face” as that, something is IMO, seriously wrong.

    I think the Boeing powerplant guys are realizing this and scrambling to get an engine that is low risk and within the demonstrated design space of past engines. They don’t want to deal with irate customers screaming that the AC sucks fuel and be put off by the GE machine until they get the engine fixed which will take years. In contrast, they know the pressures and temperatures of the GTF have been done already. The gearbox durability of the fan gear drive has been done already by P&W Canada AND Sikorsky – independently in totally different applications. IMO, P&W is a historically conservative company as is their parent – UTC. GE is a historically risk – taking company. In fighting against the A320NEO, Boeing doesn’t need a loser. They need to maintain market share with a simple, drama-free entry into market for the MAX. That’s why they HAVE to look at the GTF. Nuf said,

  3. Interesting development if true, but also puts Boeing in a bigger dilemma with the Max. Being involved with fleet planning at my carrier, Boeing has given us information which suggests that the OEW increase for e.g. the 737-8 and the proposed higher MZFW means that the -8 loses 1000 kgs of payload vs. 737-800. A GTF installation would probably be heavier than the Leap, potentially losing more payload, which it cannot afford to. So that means looking at increasing Max weights further, resulting in more strengthening and still higher OEW. Is Boeing stuck in a Catch 22 and effectively at the end of how far the 737 can be develoed?

  4. I will be very very surprised if boeing puts the GTF on the MAX. From what I gather so far, the P&W GTF engine proposed for the max will have a 71 inch fan size vs 69 inch for the leap. By reading boeing statements on the MAX work so far, I don’t get an indication that those design changes are done with different engine than the LEAP in mind. So if Boeing is going to put the GTF on the MAX the EIS of that version of the MAX will come much later than the 2017 EIS of the LEAP. Certainly that is not good for business since boeing is playing catch up on the Airbus NEO.

  5. I think there is another potential risk to the MAX project. Capacity (and capacity flexibility) are very important (the most important?) when selecting an airframe. Boeing has sized the 737 NGs -800 and -900 smartly in between the A320 and much larger A321. Making it possible to spread operating costs over more seats. (Hence their marketing focus on seat mile costs).

    The 1988 A320 seems to have become smallish for airlines willing to replace older A320s. The A321 however is much larger, heavier and more expensive then the A320. That won’t change with the new NEOs. Ryanair, Easyjet and Jetblue therefor seem to have asked for such an “inbetween” 200 seat A320 variant. Now if e.g. O’Leary / Air France-KLM / Easyjet would do a launch order for 200 x A320 NEO “Plus” aircraft, I can imagine Boeing seriously reconsidering their MAX business case. It would corner the most successful 737NG variant, the -800.


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