Boeing’s factory complex on the south shore of Lake Washington has seen busy times before. In July 1945 alone, the Renton workforce built 160 B-29 bombers, representing about 5.4 million kg (11.9 million lb) of combined empty weight. Seventy years later, an expanded factory with 112 square metres (1.2 million square feet) under roof is again testing the limits of aerospace productivity at a single site.

Only 12 years ago, the same factory produced 737s at a rate of 17 aircraft per month, along with about one monthly 757 delivery from an adjacent line. The 757 line was closed two years later, as 737 output rose to an impressive 21 aircraft per month.

That was just the beginning of a decade-long surge of productivity growth. Since 2015, Boeing has doubled 737 output from Renton to 42 aircraft per month. Deliveries will continue to grow to 47 per month in 2017, 52 per month in 2018 and perhaps even higher.

Marty Chamberlin, director of factory operations, recalls “great anxiety over things like 31 per month”.

The output growth at the Renton site has coincided with a steady reimagining of how the aircraft are built. A pulsed line was quickly transformed early in the last decade into a moving line. Then the vertical wing assembly tooling jigs were replaced by a horizontal system, with robotic vehicles moving the structures to each station.

Now, the focus on driving productivity is in the systems integration area. The Renton facility used to have only two lines, and each line included a dedicated systems integration tool with three positions each. It was here that Boeing’s workers installed the hydraulic lines and actuation systems to the fuselage shells that are delivered from the Spirit AeroSystems factory in Wichita, Kansas.

The arrival of the first 737 Max at the final assembly stage later this year will open a third assembly line in the Renton factory. Its presence and the ever-increasing production rates meant that Boeing needed to consolidate the systems integration tool into a single complex.

The new structure is three storeys tall instead, replacing the two-storey system before. The 737 fuselages are loaded three-abreast into the first station. As each station is completed, the tooling apparatus in front of the fuselage opens like a drawbridge, and the fuselages are moved to a second station.

“Our footprint has been collapsing over the years,” Chamberlin says. “So how do we take more advantage of the cubic space?”

Components of the first 737 Max have already entered the production system. The first completed aircraft will be rolled out of the factory at the end of this year. First flight of the CFM International Leap-1B-powered aircraft is scheduled in 2016, with delivery currently scheduled for the third quarter of 2017.

The new variant will only make Boeing’s rising production rates more challenging, but it also increases Renton’s overall capacity. The 737 Max will be assembled on a third assembly line. In theory, all three lines will have the capacity to produce 21 aircraft per month – the limit of the two lines now producing 737NGs. A third line at the same rate raises Boeing’s production capacity to 63 737NGs and Max jets after 2018.

In terms of metal, the combined empty weight of 63 737s still does represent even half of the structural mass of 160 B-29s in 1945. But in every other respect, Renton has never been busier.

Source: Cirium Dashboard