Aviation Update ~ Boeing Readies 737 MAX For First Flight

B737b MAX PreFlight Test

 

Boeing is set to begin preflight tests of the first 737 MAX, following a Dec. 8 unveiling event for employees at its Renton, Washington, facility.

The aircraft—expected to make its first flight in 2016—rolled off the production line and into the paint hangar on Nov. 30, the exact date defined in the program schedule four years ago. Its entry-into-service targeted for the third quarter of 2017 with launch customer Southwest Airlines, the MAX will succeed the 737 Next Generation (NG) that first rolled out 19 years ago to the day in 1996.

The 737 MAX makes its debut just as its arch rival, the Airbus A320neo, nears service entry with launch airline Qatar Airways. Despite the 60-40 market share lead enjoyed by the A320neo, the 737 MAX’s expected 20% fuel-burn improvement over the current 737 model will continue to attract sustained orders, 737 MAX Vice President And General Manager Keith Leverkuhn said. “We are very comfortable with the way the market is settling out,” he said. “It’s not unlike where we are with the NG and the A320 today, which is about 50-50, and I’d expect that to continue. It’s going to be a dog fight for every campaign, and for us to demonstrate we have the right product at the right price.”

Firm orders for the NEO—launched more than one year ahead of the MAX—have now reached more than 4,410, compared to the MAX’s approximately 2,930. But Leverkuhn says that, “since the MAX has been available it has been about 50-50.”

B737 MAX Rollout

Key design changes introduced with the MAX include the higher-bypass CFM Leap-1B engine with a larger diameter fan and bigger flight-deck displays. The new aircraft also has several wing improvements, including the addition of a large, bifurcated winglet, a nose-gear extension to improve ground clearance and the incorporation of a lower drag tail cone. Fan diameter was increased to 69.4 in., but Boeing avoided a commensurate increase in nacelle diameter. It achieved this by introducing a closer-fitting thrust reverser lined with titanium—instead of one lined with the typical insulated composite—to withstand the higher temperatures. However, reverser supplier Spirit AeroSystems recently dropped GKN as supplier of the titanium lining amidst mounting concerns about the U.K. company’s ability to produce the unit at the coming high rates. Sufficient titanium units are available for the initial batch of test-aircraft, but a new solution has been devised for the longer term.

“Fortunately we’ve been looking at alternatives and we believe there’s a really good alternative with no weight or performance impacts,” Leverkuhn says. Without providing specific details, he adds: “It isn’t a titanium solution, but it’s a different way of how we typically build thrust reversers and protect them from heat. It’s not unlike how we are doing it on other airplanes, and in fact is very similar to what we are doing on 777X. So as they’ve been developing their concept, we’ve been saying that will probably work for the MAX as well.” The new design is thought to incorporate a form of ceramic matrix composite (CMC), though Boeing declined to comment.

Following the loading of the first wing spar into production jigs in May, the Boeing 737 assembly workers have “met all the milestones we had set for the program, including wing loading into the wing-body join,” Leverkuhn says. Noting that joining of the fuselage sections, completion of wing-body mating and power-on for aircraft systems were all accomplished on time, Leverkuhn says the program remains on schedule, or in some cases ahead, as additional test aircraft are completed: “We are now transitioning to flight test, so we are going to spend some time with the aircraft and prepare it for flight tests, which will happen early in the New Year.”

Flight tests with the first aircraft, a 737-8 dubbed 1A001, will follow the standard Boeing format of “flying it slow and low to begin with,” so that engineers can be sure they understand its handling qualities and verify that what they modeled and saw in the wind tunnel was correct, Leverkuhn says. “Then we will expand the envelope to make sure we can fly higher and faster and clear flutter.”

Four 737-8s will be involved in the initial MAX certification plan, before the 737-9 and 737-7 derivatives follow. Certification of the aircraft’s Leap-1B engine is expected shortly after first flight, while certification of the initial 737-8 is expected in the first half of 2017. The second test-aircraft, 1A002, is in final assembly and undergoing systems checks. Those include swings of its landing gear, as the aircraft awaits installation of its engines. The wing set for 1A003 is in "lay down" ahead of schedule, in readiness for joining with the third MAX fuselage shipped from Spirit AeroSystems in Wichita, Kansas. “We are already hard at work on airplanes two and three, and four will load later on,” he adds.