For many months Boeing expressed a preference to introduce an all-new airplane in the narrowbody jet segment to replace its 737NG family by 2019. But sometimes market reality gets in the way of what one really wants, and Boeing ultimately settled on the most basic re-engining plan possible for the 737-700, -800 and -900. It called the new series the 737 MAX, and projected entry into service in 2017–possibly two years later than Airbus’s A320neo.

Boeing believes airlines will find the MAX family worth the wait, and as of  September five separate customers had already signed “commitments” or letters of intent covering 496 airplanes. Of course, the order that ultimately convinced Boeing to announce an imminent program launch came from American Airlines, which committed to a firm order for 100 of the re-engined Boeing product. The U.S. carrier simultaneously opted for 130 A320neos, as if to remind Boeing that it had an alternative and would not wait for long-term 737 replacement plans to unfold.

Indeed, it seems that those in favor of the re-engining approach all along can thank American Airlines and, by extension, Airbus, for finally convincing the U.S. manufacturer to jump off the proverbial fence. After all, in the balance hung an order for 200 Boeing airplanes, including 100 of it current 737NGs, and if not for the existence of the A320neo, American might well have opted to maintain its exclusive relationship with Boeing. 

The decision to re-engine comes despite several signals sent by Boeing over the past year that its customers would rather see it develop an all-new airplane for introduction sometime around the turn of the decade. During a July 20 press conference in Dallas, Texas, Boeing Commercial Airplanes CEO Jim Albaugh attempted to explain the reason for the seemingly abrupt change of heart.

“The technology is there to do a new airplane, but the issue is the production system…how quickly you could ramp up and how efficiently you could build forty, fifty, sixty composite airplanes a month,” said Albaugh. “Quite frankly, we did not have those answers, and the longer it took to get that answer, the more concern we got from our customers about the fact that they needed a more fuel-efficient airplane now rather than later.” 

Meanwhile, Boeing still hasn’t answered the question of where it will build the MAX. The current site of 737 production–Renton, Washington–tops the list of possibilities, said Albaugh, but plans already call for that factory to raise monthly production rates from today’s 35 to 42 by early 2014. A transition from 737NGs to 737 MAXs and a likely need for further increases by the time the re-engined airplanes enter production in 2017 could figure prominently into Boeing’s decision. In any case, in early September Albaugh said the company would announce a plan within six to eight months.

Not coincidentally, the new nomenclature for the re-engined 737s closely resembles that of the 787 family; Boeing has adopted the names 737 MAX 7, MAX 8 and MAX 9, respectively, to correspond with the comparably sized 737-700, -800 and -900NG.

Boeing claims the new 737 MAX 8 will produce a 7-percent operating cost advantage over the offering from Airbus, whose A320neo family has already drawn firm orders and “commitments” for more than 1,200 airplanes since its launch last December. Boeing also promises a 16-percent cost advantage over the current A320. The company’s calculations show that, compared with a fleet of a hundred 737-800s, a fleet consisting of the same number of dual-class 737 MAX 8s will use nearly 175 million pounds less fuel per year based on a 500-nm mission, save $85.5 million in annual fuel costs assuming a price of $3.22 per gallon, emit 277,000 tons less CO₂ into the environment and save nearly $79.4 million per year in term of cash operating cost.

Of course, most of those benefits will come from the switch to CFM56s to the new CFM Leap-1B, “optimized” specifically for the 737.

One element of “optimization” involves the fan diameter, which Boeing has said will span either 66 inches or 68 inches, compared with the 61.8-inch fan on the CFM56-7B. In either case, it will likely have to “slightly” modify the nose gear to create enough ground clearance for the engine nacelles. Still, Boeing steadfastly denies the popular notion that the Airbus A320’s higher stance makes for an easier engine retrofit, notwithstanding the fact that the CFM-powered version of the A320neo will use a 78-inch fan, while the fan on the Pratt & Whitney PW1100G-powered Airbus will span 81 inches.

“It’s a mistake to think that it’s more difficult to install new engines on the 737 than it is for Airbus to install them on the A320,” replied Boeing to a query about the issue. “Boeing has a long history of integrating engines and wings with the latest tools and processes, not to mention an experienced workforce [that] has just completed two development programs, including a new engine and wing on the 747-8.”

Other changes will include a “revised” tail cone to reduce drag and improve fuel efficiency, and external nacelle chevrons similar to those on the 747-8 and 787 for more efficient airflow mix and less noise, said Boeing. 

Albaugh said Boeing’s first MAX delivery would go to a carrier other than American Airlines. In fact, he said, 85 percent of the backlog for the airplanes resides outside the U.S. Boeing projects a global 20-year demand in the 737 segment for 23,000 airplanes worth some $2 trillion.