Boeing’s latest jet, the 737 MAX, should start delivering to airlines by May, even as 737 production ramps up to 47 jets per month. To handle it all at the Renton plant, Boeing has installed a new automated wing spar assembly line and re-choreographed how it finishes the wings.

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As Boeing prepares to deliver its first 737 MAX airplane and to boost production of single-aisle jets 12 percent — both by May — the Renton factory has geared up with additional refinements of its already humming manufacturing methods.

Boeing showed off the latest innovations inside its Renton factory on a tour of the 737 wing facility Monday, showcasing impressive new robotic machines as well as more efficient ways of deploying its mechanics. While it introduces the new 737 MAX, the company is also ramping up its 737 production rate to 47 per month, from 42.

A new robotic tool does all the drilling and fastening for parts of the new Boeing 737 MAX. (Mike Siegel / The Seattle Times)

Vice president and general manager Keith Leverkuhn brimmed with good news about the program schedule and the new jet’s performance.

Leverkuhn said the MAX flight test program has just one test to complete and should get certification from the Federal Aviation Administration (FAA) within “days or weeks.”

He said the fourth flight test airplane last month completed a 100-flight-hour tour of the Pacific Rim — including a cold soak test in Yakutsk, Russia, and a stop in hot and humid Darwin, Australia — that produced just a single “squawk,” the term used to denote the airplane performing even slightly off expectations.

Having already built 13 of the initial MAX 8 models, all now sitting around Renton airfield awaiting FAA certification, Boeing showed off the first of the large MAX 9 models sitting on the assembly line and almost ready to roll out.

Its advanced winglets, sweeping up and down from the wingtip, set it apart from the current model 737s on the adjacent line, with their traditional upward-swept winglets.

Also very different were the MAX’s new LEAP engines.

With a fan diameter of more than 69 inches, the LEAP seemed to dwarf the older CFM-56 engine, with its 61-inch fan, on a nearby current model 737-900ER.

The MAX 9 will begin flight tests in April, Leverkuhn said.

Soon after, the smaller MAX 7 will come along, and then the high-density version that budget airline Ryanair covets, the MAX200, seating 199 passengers.

And Leverkuhn said Boeing is actively seeking input from airlines on whether it should add one more even larger model, the MAX 10, to the family.

New wing spar automation

To make all this possible, dramatic changes are well underway inside the Renton factory.

New automated machines are revolutionizing assembly of the wing spars — the long beams along the leading and trailing edges of each wing.

And on the other side of the building, crews of engineers and mechanics who finish the wings by installing all the wiring, plumbing and control systems have figured out how to accommodate the coming rate increases — up to 52 jets per month next year, then 57 jets per month in 2019 — without adding another line to their area.

In a plant that has steadily morphed into the most productive airplane factory in the world, Barry Lewis, director of 737 Wing Operations, declared on Monday that “the transformation is almost complete.”

On one side of the wing building, Boeing currently has 10 large machines that it introduced in 1997 when it developed the current model of the 737.

Known as Automated Spar Assembly Tools, or ASAT machines, these drill and fasten the heavy spars that are the structural spines along the edges of the wings.

To increase 737 output by 36 percent over the next three years, Boeing at first thought to buy some more ASAT machines, which were designed and supplied in the late 1990s by Mukilteo-based engineering firm Electroimpact.

But Boeing realized it doesn’t have room. The ASAT machines are huge, with a tall, wide gantry straddling the 60-foot-long spar.

So all 10 of these machines will be phased out by year end, replaced by just two fully automated Spar Assembly Line (SAL) cells – newly designed by Electroimpact and already in place.

Each cell contains two Electroimpact drilling and fastening machines, much smaller than the ASAT machines, that zip along a single spar simultaneously, drilling and filling as they go.

Critically, alongside the business end of each machine is a robotic arm that swings in and changes the drill head and the fastener whenever a different type of hole is to be drilled.

On the old ASAT machines, changing the tools is done manually, adding a great deal of down time. In the new SAL cells, that’s all automated.

At one end of the SAL cell, two operators sat before a control console Monday intently watching eight big screens, including four video screens monitoring every move of the machines.

“In future, whether we need two operators (or just one) per cell is to be determined,” Lewis said.

Improving human efficiency

The new SAL cells, occupying 80 percent less floor space than the ASAT machines they replace, are just the latest push in Renton’s drive toward automation.

In recent years, Boeing has transformed the way it installs systems in the 737 fuselages by shifting to a moving line. It also has automated the way it assembles the skin panels for the wings using huge Electroimpact machines.

Earlier, final assembly of the wings was made more efficient and more automated with a move from putting them together while hanging vertically in fixed tools to a more ergonomic and faster horizontal build line, in which the wings are assembled lying flat.

And yet Lewis deflected concerns about robots replacing humans, pointing out that Boeing will be hiring modestly in Renton over the next few years, not losing workers.

“We’re going up in rate,” he said. “More planes means more jobs.”

In another sector of the wing building, where the wings are completed with all the wiring and ducting added, the second set of MAX 9 wings awaited delivery Monday evening to the final assembly line.

There, Lewis praised his team of engineers and mechanics for figuring out how Boeing can increase throughput as high as 57 pairs of wings per month without adding any new machinery.

“It’s people thinking of better ways to do it,” said Lewis.

The workers divided up the work into smaller packages, which could be accomplished with more people working on the wing simultaneously yet with their moves choreographed so as not to get in each other’s way.

Darwin Stachowiak, a team lead on the wing installation, said that by having front line employees think through the most efficient way to get the work done, “we’ve really streamlined the way we build these wings.”

The 737 will be 50 years old in April.

Yet if all the production increases in Renton go to plan, and Boeing decides to go forward with the MAX 10, Boeing will within a few years be making more 737s than ever before, and airlines will be flying five new variants of the jet.

Right now, everything is on track to accomplish just that.