After months of hesitation, Boeing has finally committed to a re-engined 737 in response to the massive success of Airbus’s A320neo. Ian Goold examines the programme.
Boeing is reporting "overwhelming demand" for its re-engined 737 MAX development, launched at the end of August after months of apparent indecision.
Before the go-ahead for the programme was granted by Boeing directors, five operators made undefined “commitments” for 496 units of the new variant, which the manufacturer claims will offer 4 percent lower fuel-burn than the rival Airbus A320neo.
Powered by CFM International LEAP-1B engines, the 737 MAX is expected to enter service in 2017. The re-engined 737-700, -800 and -900 models will be dubbed 737-7, -8 and -9, following the style adopted for the 787.
A major consideration for Boeing had been whether to accept the high engineering and financial burden of an all-new single-aisle aircraft development, or to go for incremental improvements in efficiency of the current design. Ultimately, the company’s decision was revealed only in a reference by American Airlines to its fleet plans (which have seen the US manufacturer lose out heavily to Airbus [see feature in September 2011 issue of Asian Aviation]).
Boeing has set aside 64 to 76 months for development of the aircraft, scheduled for first delivery in 2017. That is markedly longer than the 48 months initially planned for the all-new 787.
“We want to make sure that any date that we quote is [one] we can meet. And I'd rather under-promise and over-deliver than over-promise and under-deliver,” says Boeing Commercial Airplanes Chief Executive Officer Jim Albaugh.
The 737 MAX features significant modifications from current variants. These include: larger engine nacelles, incorporating noise-reducing chevrons such as those found on the 747-8; a 787-style tail cone and tail lights; and elimination of the 737-700's aft-body join. The stronger wing, which may offer reduced drag, will feature trailing edges with reshaped flap-rail fairings.
“Clearly with the heavier engine, you'll have to do some changes to the wing, some changes to the side-of-body join, some localised stiffening of the airplane," Albaugh says.
According to Jeff Turner, chief executive of Spirit Aero Systems, Boeing's largest single 737 structures supplier, the new 737 variant will require “a pylon [and] a new nacelle for a new engine. I'm sure it's going to have some upgrades to parts of the fuselage to handle loads".
Albaugh adds: "There are a couple of [very minimal] things we're going to make more fly-by-wire." Detailed Boeing assessments are underway to incorporate a laminar-flow engine nacelle and a hybrid laminar flow tailfin for improved operating economics.
Boeing is keen to avoid the "mission creep" that afflicted the 747-8 GEnx-2B re-engining programme.
"We want to limit the scope of work [especially] associated with the engine," Albaugh says. He has told development engineers that he doesn't want "to hear 'simple' and 're-engine' in the same phrase. But we're going to make this the simplest re-engine possible”.
"We want to make sure we have compatibility with airplanes we've already delivered," the executive says. For example, customers have asked Boeing to not to change the cockpit and "our plans are not to do that". On the question of certification, Albaugh acknowledges that "there are some questions we're going to have to work [through] with the Federal Aviation Administration".
Engineering efforts for the Leap-1B re-engining are in the hands of Vice-President and General Manager Bob Feldmann, who most recently managed Boeing's Surveillance and Engagement business. His deputy is Vice-President, Chief Project Engineer and Deputy Programme Manager Michael Teal, who has come from the 747-8 programme.
Since the launch, major 737 operator Southwest Airlines has been analysing the new variant. The carrier’s Chief Executive Officer Gary Kelly says that the low-cost carrier is "engaging with [the manufacturer] to try to understand the aircraft". As always, Irish low-cost carrier Ryanair – Boeing's largest 737 export customer – is looking for maximum economy, and has said it will not be interested unless re-engined aircraft offer fuel savings of "somewhere near 10 percent".
Since launch customer American will receive its first re-engined machine only in 2018, it is clear that another airline will inaugurate services. Albaugh does not rule out current customers switching orders, suggesting that they might want to "take a hard look" at the new machine. (Airbus refuses to allow such flexibility with its A320neo.)
Most of the carriers committing to the re-engined Boeing 737 operate outside the USA and are "the top airlines in the world", claims Albaugh. Apart from American, the other four committed customers are believes to be among the Boeing faithful: Alaska Airlines, Copa, Delta Air Lines, FlyDubai, Gol, Lion Air, Malaysia Airlines, Norwegian Air Shuttle, Ryanair, Southwest Airlines, United Airlines and TUI Travel.
The Leap-1B-powered 737 has generally met a positive response from the financial world. Moody's suggests that the development costs "won't be anywhere near the level of … building an entirely new airframe", while Credit Suisse equity research analysts say the airline interest is “above expectations and a very positive indicator of demand for what has been viewed as a 'me-too' offering”.
Wedbush analyst Kenneth Herbert believes that Boeing share prices could rise as other manufacturing problems and delays are overcome, while Jefferies analyst Howard Rubel says that the new model tackles "a fundamental weakness in Boeing's offerings".
As of late September, the industry was awaiting a decision on the new engine's fan diameter for the 737 application. It was expected to be 66 or 68 inches. The larger of the sizes could require some nose landing-gear changes to maintain a minimum 17-inch nacelle ground clearance.
Current CFM56-7BE engines with a 61-in fan offer six inches of margin. Albaugh says no modification is needed if a 66-in fan is selected, but he concedes that, with the larger diameter, there is "a very low probability we'll have to 'touch' the front gear". Albaugh acknowledges that a larger fan would provide better efficiency because of the higher bypass ratio, but "also what you find with the bigger fan is that you get more weight and more drag".
Apparently anticipating a compromise, the Boeing official says that if the largest fan is chosen "we have that built into our reserve for the development of this programme and we have it built into the reserve for the schedule ". A Leap-1B with a 66-inch fan is expected to offer 13-14 percent better specific fuel consumption than a CFM56-7B with a 61-inch fan does on current 737s.
Analysts at Jefferies suggest the CFM solution is "likely to run hotter and may need to eliminate a compressor stage to stay within weight tolerances". The 2017 service-entry date is seen as permitting time for full consideration of both options.
A dissenting voice is that of David Hess, chief executive of Pratt & Whitney Engines, manufacturer of the competing PW1400G geared turbofan engine.
He says that while Boeing expects to see an all-new single-aisle design in the 2020s, the manufacturer might "not be able to wait that long, because the engine it has chosen is too small. If they feel they don't have a competitive airplane, they may be forced to accelerate or look at their plans for a [new aircraft]".
Finally, another decision for Boeing is the site for manufacture of the new 737 variant, which might not be built at Renton where all previous 737s have been constructed. It expects to announce a decision in about six to eight months' time from its late-August launch date. "[As] on any new programme, we're taking the opportunity to [decide] where we do the work. Our Renton facility has demonstrated we know how to build this airplane, but we are going to look at other sites".
There is no shortage of offers from points all over Boeing's home state of Washington and further afield. A number of county and city councils and agencies and a trade-union district lodge are contributing funds to a US$600,000 study to keep Boeing's next aircraft in Washington State.
State and Snohomish County representatives want to see the new Boeing plant brought to Everett's Paine Field as part of larger plans to expand local aerospace training and reduce regulatory manufacturing hurdles. Elsewhere in Washington, the Port of Bremerton is lobbying on behalf of Bremerton National Airport on Kitsap Peninsula, where there are more than 1,000 acres of available land. Another bidder is Long Beach in southern California, where Boeing employs approximately 5,000 workers at the former McDonnell Douglas plant.
Why did Boeing marketers choose MAX as a name for the Leap-1B-powered 737? According to Nicole Piasecki, Boeing Commercial Airplanes’ vice-president for business development and strategic integration: “We wanted to capture how exceptional the 737 is in performance [and] to differentiate the -7, -8, and -9 [variants].
“We wanted to make sure the name was easily identifiable and represented the best – the 'gold standard'. We wanted to make sure it 'talked' about what it was going to bring: maximum benefit, maximum competitive advantage, maximum value, and maximum in what [it] could deliver to our customers."
For a long time, Boeing favoured a clean-sheet New Small Airplane (NSA), which it continued to study long after Airbus launched the A320neo last December. Two product-development teams studied the NSA and an alternative re-engined 737NG. Six months ago [April], Boeing said the NSA was "the leader in the clubhouse".
Major factors in Boeing's change of mind were the need to participate in American Airlines’ re-equipment plans and the enormous market response to the Airbus A320neo. Enthusiasm for the NSA, which would have been introduced around 2019-20, was offset by reservations about suppliers' abilities to accommodate a new aircraft while accelerating other production lines.
An earlier 737 re-engining study, dubbed 737RE, used a 70-inch fan that required an 8-inch nose landing-gear extension to ensure sufficient nacelle ground clearance. The longer gear would have forced further structural changes: to the rear fuselage and empennage and in the Section 41 forward-fuselage lower lobe, which would have needed a modified electrical-equipment bay.