Boeing locks in the design for the Everett-built 777X

EVERETT — Boeing has nailed down all the major parts of its new 777-9, and the airplane’s design is performing as well as the company expected.

After hundreds of engineering studies, wind tunnel tests and computer modelling, the plane reached a firm configuration Tuesday, as scheduled, said Bob Feldmann, Boeing Commercial Airplanes vice president and general manager of the 777X program.

“It does everything we want it to, and it does it very well,” he said.

The 777X family of airplanes is to replace the venerable 777-200 and -300 airplanes, which dominate long-haul travel. The 777-9, capable of carrying more than 400 passengers, will be one of the largest commercial planes in the air.

Firm configuration is the first of the major design milestones in an airplane’s development. No major changes to the airplane’s design and performance specifications are expected after this point.

For the airlines buying the airplanes, it means they now really know what they would get, said Stan Sorscher, a former Boeing engineer. He is currently a union official for the Society for Professional Engineering Employees in Aerospace, which represents engineers and technical workers at Boeing.

Before that point, “if you’re one of the early customers, it’s not clear what you’re buying, because the plane’s configuration could change down the road,” he said.

It also matters for engineers at Boeing and its suppliers, who will now begin designing every detail of the airplane, which is to go into production in 2017 and start flying passengers in 2020. The smaller 777-8 is expected to follow a couple years later.

So far, at least six airlines have ordered 306 777Xs, according to Boeing. More than 200 of those orders are for the 777-9.

Engineers on the 777X program conducted hundreds of studies to nail down the performance specifications for the plane’s major components, Feldmann said.

The studies determined the best balance of a multitude of criteria — such as weight, strength, ease of production, cost, aerodynamic qualities — for each component on the airplane. They’re called “trade studies” because that balancing act often requires trading gains in some criteria for setbacks in others.

The 777-9 studies led to tweaks to the plane’s design but no significant rework, Feldmann said.

The biggest changes that have been made since the 777X was unveiled at the Dubai Airshow in November 2013 include slightly reducing the wingspan, removing scalloped edges on engine nacelles and removing a drag-reducing surface known as hybrid laminar flow control. Given the size of the plane, the system wouldn’t deliver the benefits to justify the added weight or cost, a Boeing executive said earlier this summer.

Boeing has been developing component prototypes for the airplane for at least a year. It began work on wing spars late last year.

The prototype work is focused on the critical parts of the airplane’s structure, what Boeing calls “high-integration areas,” such as where the plane’s wings connect with the fuselage, Feldmann said.

GE Aviation is already testing the airplane’s engine, the GE9X.

Boeing is currently developing prototypes for the airplane’s folding wing tips, which will let engineers begin testing how reliable and easy the part is to maintain, he said.

Boeing has been designing the process for building the 777X “at the same pace” as the aircraft itself, he said.

The airplane and the wings will be assembled in Everett.

With room for more than 400 passengers, the 777-9 sneaks into the biggest class of commercial airplanes — “very large aircraft,” a category occupied by the 747 and Airbus A380, said Scott Hamilton, an aerospace industry analyst and owner of Issaquah-based Leeham Co.

While Boeing is not selling it as a jumbo, the 777-9 “is what has finally killed off the 747-8” passenger version, he said.

No airline has ordered a 747-8 passenger plane since the 777X was unveiled in 2013.

For the time being, Boeing’s 777-9 doesn’t have any competitors in the market.

“Airbus still has to figure out how to respond to that airplane,” Hamilton said. “Do they just abandon that market segment to Boeing? Is there enough demand for two airplanes of that size?”

Dan Catchpole: 425-339-3454; dcatchpole@heraldnet.com; Twitter: @dcatchpole.