Flexible 777 production system will build metal and composite-winged variants on same line.

Any doubts about the scale of the changes involved in Boeing’s 777X derivative or the company’s commitment to its new long-haul flagship are quickly dispelled with a visit to the giant construction site in Everett where the aircraft’s composite wing will be built.

Building of the sprawling  $1 billion composite wing center (CWC) and the nearby advanced fuselage assembly facility extension for the 777/777X together mark one of the largest single expansion phases for the site since the mid-1960s when the first trees were felled for the start of the 747 program. When completed next May the CWC will cover almost 1.3 million sq. ft., while the expansion of Building 40-27 for fuselage assembly adds a further 325,000 sq. ft. The CWC will have a clear span of 460 ft., more than 100 ft. wider than the largest now.

At the heart of the new building will be three enormous autoclaves for curing the skins and spars of the 114 ft.-long main wing sections. The length of each will be extended for flight by an 11 ft. foldable wingtip section to give the 777X an overall span of 212 ft. 8 in. retracted and 235 ft. 5 in. when deployed. The sheer size of each means the short journey across the airfield to the CWC will take up to four days and concludes with the unit being positioned on rollers into specially prepared sunken foundations.

On another part of the Everett site Boeing has been perfecting production and assembly techniques on a prototype wing box. Measuring 80 ft. long it comprises composite upper and lower skins and the internal wingbox structure. The wing, which is a fourth-generation derivative of the 787 design, epitomizes the challenges faced by Boeing in developing the 777X. “They are not so much about the design,” says Boeing Airplane Development SVP and general manager Scott Fancher, “it’s pulling the production system together, building the plant, building the tooling, getting everything installed. It’s going to be highly automated wing, so we have the automation system to purchase and integrate and stand up.

“The wing is a derivative from a design standpoint. It is stretched and has a wing fold, but we are seeing no major risks. The aerodynamic performance of the wing is exactly where we want it to be. We have refined the design and are taking the part count down so that it is a simpler design to fabricate and produce,” says Fancher. Much of this simplification has come out of the wing fold and its actuation mechanism. “Over the past year to 18 months we’ve taken 40% of the parts out of the wing fold and that’s by just through refining the design,” he adds. The wing fold itself has achieved “full market acceptance. We have had no questions about that for more than a year now.”

The 777X empennage and fuselage will also be produced using advanced, more robotic processes now being developed and tested for initial introduction on the current 777. Principal amongst these is the FAUB (fuselage assembly upright build) automated drilling and riveting system being installed in the 40-27 building extension. Resembling the techniques used by car manufacturers, the FAUB robots work cooperatively inside and outside the forward and aft fuselage sections.   

To ensure the new process has no negative impact on structural integrity a full fuselage barrel made using both FAUB and conventional manual riveting processes will begin fatigue tests in August. “It is a bit of a Franken-barrel, but we believe this will cover fatigue for these specific automation portions for the 777X analysis,” says 777/777X manufacturing VP Jason Clark. Traditional complete static and fatigue test airframes will also be built for the program, he adds. 

To protect the current 787 assembly line, which is producing 100 aircraft per year, Boeing will create a parallel line “to allow us to slowly ramp on that technology,” says Clark. While the FAUB becomes established in the 40-27 with full implementation on the 777 in 2016, the low rate initial production line for the 777X will be set up in the 40-24 bay which was used for the 787 temporary surge line.  Boeing plans to close out the 787 work on the line by the end of the year as production steadies at a higher rate between the adjacent assembly line in Everett’s 40-26 bay and the company’s facility in Charleston, South Carolina.