Boeing announces design changes for 737 MAX

Boeing has announced which will the engine for the 737MAX

The company released the new details Thursday to try to stem the momentum of the hot selling A320neo, Airbus' revamp of its single-aisle jet family that features an even larger new engine that will produce the most fuel-efficient and least-costly jet in the single-aisle market.

The current models of the Airbus A320 and the Boeing 737 split the single-aisle market roughly down the middle. Boeing needs the MAX to maintain that share against the neo. The 737 chief project engineer, said the current 737 is lighter and more fuel efficient than the current A320, and the new MAX design will leapfrog the neo and have 7 percent better operating economics. The engine for the 737 MAX will have a larger, 68-inch diameter fan and a lower weight affects about 30 percent of its operating costs, and more efficient, lighter design and requires less thrust than other airplanes in this class, which is important because weight and thrust have a significant effect on fuel efficiency and operating costs. Airbus decided two years ago to add a new engine to its A320 single-aisle jet and received hundreds of firm orders at this year's air show. Boeing followed suit and said Thursday that it now has 600 commitments for the new MAX, up from 496 when it launched the program in August.

John Hamilton, the 737 chief project engineer, said:"There's a much better structural efficiency that goes into the 737 design than into the Airbus design," Boeing will increase the engine fan size from 61 inches on today's 737 to 68 inches on the new MAX engine — called the LEAP, being developed by CFM International. A bigger fan sucks in more air, providing greater thrust. But Boeing's increase in engine fan size just matches the fan size of today's A320.

"Today, our (737) engine is 7 inches smaller than the Airbus (A320) engine, and yet we have lower operating costs," Hamilton said. "The 737-900ER is nearly 50 pounds lighter per seat" than the comparable A321. The MAX "doesn't need the high thrust requirements that the Airbus product has," he said. "When you look at drag, fuel efficiency and weight, the 68-inch fan is really the optimum solution for the 737 airplane going forward." It said in one year, a fleet of 100 will save 175 million pounds of jet fuel and save $85 million in fuel costs. Boeing said the amount of fuel burned should be 16 percent less than the competitors are burning now and 4 percent less than future offerings.

Airbus spokeswoman Mary Anne Greczyn dismissed that claim, saying Boeing is struggling to overcome a structural limitation: that the 737 wing sits closer to the ground than the A320's wing, so that a larger, more fuel-efficient fan won't fit. "If a smaller fan engine were to generate the appropriate level of efficiency, we could have easily incorporated that, since we are not constrained as our competitor, " Greczyn said. "The A320neo family is designed to benefit from the aircraft's inherent advantage." He acknowledged that Boeing is behind Airbus in its re-engine program, the A320neo, but said there's a lot of interest from airlines in Boeing's model. "It's a huge growth market," he said of single-aisle jets. "The customers are responding quite well, and we expect several hundred more commitments soon."

Hamilton said the engine will be the largest change for the 737 MAX, but he noted several smaller ones. Boeing will refine the 737 airframe design in relatively small ways without changing the overall size of the planes. The larger, heavier engine will necessitate strengthening of the wing and parts of the fuselage, as well as designing a heftier strut to hold the engine on the wing and making minor system changes. Boeing will also lengthen the nose landing gear to raise the wing slightly and reshape the tail cone to streamline the air flow. and it will introduce fly-by-wire spoilers — the hinged parts on the wing that rise on landing to increase drag — which means they will be operated by computer rather than by direct cable connections.

Boeing said Thursday it continues to work with customers to see what they want in a new model aircraft. Boeing launched the 737 MAX in August; Airbus launched the neo last December and by the summer had captured more than 1,000 orders from airlines eager for more fuel-efficient planes.


Hamilton said customers are "responding well" to Boeing's preliminary design and that he expects "several hundred more commitments soon." Boeing won't finalize the design until 2013, he said.

The neo, due to enter service in 2015, at the end of September had 918 firm orders plus an additional 319 purchase commitments. The MAX, scheduled to enter service in 2017, has no firm orders. But on Thursday Boeing said it has garnered 600 purchase commitments from eight airlines, including some U.S. carriers.

Hamiliton called the 737 the most popular and reliable commercial jet and said it has sold more than 9,000 of the Renton-built aircraft.

Boeing has not announced where it will build the new 737 model, although analysts say it would be difficult for it to meet its deadlines if it tries to build entirely new production facilities elsewhere. Boeing executives say they will decide by the spring. Company spokeswoman Karen Crabtree said Thursday that the Renton site "has the skill base and knowledge to incorporate the production changes" needed for the MAX.