Boeing has started assembly of the first 737 Max 8 on schedule at its narrowbody plant in Renton, Washington, the company announced Tuesday. After the first fuselage arrived on August 21 from Spirit Aerosystems in Wichita, Kansas, mechanics began installing flight systems and insulation blankets. Crews next moved the fuselage to the wing-to-body join position on a new production line established in Renton. Mechanics then attached the wings to the body of the airplane.

In early June Boeing announced that it had started to assemble the wings for the first 737 Max, marking the official start of production of the company’s latest family of narrowbodies. 

“We continue to meet our plan on the 737 Max program thanks to the dedication of our employee team and our suppliers,” said Keith Leverkuhn, Boeing Commercial Airplanes vice president and general manager for the 737 Max program. “We have a lot more work still ahead of us, but we’re very pleased with our progress to date.”

Boeing places particular emphasis on the airplane’s newly designed winglets, which the company estimates will deliver up to a 1.8 percent fuel efficiency improvement over current “in-line” winglet designs.

“Seeing the new winglet design we validated in the wind tunnel years ago now on the first new airplane is incredible,” said Leverkuhn. “It’s just one of the features that differentiate the 737 Max and make it an amazingly fuel-efficient machine.” 

Boeing will build the first 737 Max jets exclusively on the new production line in the Renton factory. The new production line will allow the team to isolate assembly of the first 737 Max from the rest of production to help it learn and perfect the new build process while the Renton factory continues to turn out airplanes at rate of 42 a month. Once mechanics validate the production process, the company will extend Max production to the other two final assembly lines in Renton.

Since last year Boeing has restructured the factory floor in Renton yet again and installed the wing-to-body join tool that the two current production lines use, ensuring its production readiness by the time the company loads the Max. Meanwhile, the company has consolidated fuselage systems installation from two parts, each serving one assembly line, into a single new three-level, moving design tool, allowing the company to more efficiently use the available cubic space in Renton.

Boeing has set an efficiency improvement target for the Max 8—the first of four Max family members—of 14 percent over the 737-800NG, and 8 percent per seat over the A320neo. The 737 Max team remains on schedule to roll out the first completed Max 8 by the end of the year and fly it in early 2016. Launch customer Southwest Airlines plans to take delivery of the first 737 Max in the third quarter of 2017. In total, Boeing has collected orders for 2,896 Max-family jets from 58 customers.