The Boeing Co. and the Machinists union are in negotiations that reportedly could land final assembly of the 777X at Paine Field in Everett, but neither side will comment on their substance.

“We are in talks with the union. But we aren’t saying anything beyond that,” Boeing spokesman Doug Alder said in an email.

The International Association of Machinists and Aerospace Workers (IAM) won’t say much more. “There have been talks with Boeing regarding the 777X since the plane was announced months ago,” said IAM spokesman Frank Larkin by phone from Upper Marlboro, Md. “They never stopped.”

The Reuters news service first reported on increasingly “intense” negotiations early Monday, citing unnamed sources. The ostensible outcome, Reuters said, would be an extension of the current IAM contract and a decision by Boeing to do final assembly of the 777X in Everett instead of some other location, such as North Charleston, S.C. Also, Boeing would manufacture the revamped airplane’s new carbon-fiber-composite wings in the Puget Sound area.

Larkin called such details “speculative” and cautioned, “things can change. We’ll leave it at that.”

Alex Pietsch, director of the governor’s Office of Aerospace, confirmed, though, that something potentially big is afoot: “We are aware of discussions going on between the Machinists and the Boeing Co., and we are hopeful that the parties can come to an agreement.”

If all this sounds familiar, it’s because similarly quiet talks in 2011 led to the present IAM contract and an agreement by Boeing to place 737 Max final assembly in Renton. At the time, Boeing called it “a starting point of a new relationship with the IAM.”

The IAM represents some 29,000 assembly mechanics and other workers in Everett, Renton and other locations — but not in South Carolina, where the company in 2009 decided to establish a second 787 assembly line after a 57-day strike by the IAM in 2008.

Reuters quoted an unnamed source familiar with the talks as saying present discussions “are aimed at a multi-year extension to the existing machinists’ contract expiring in 2016. Another source said the contract would run until the middle of next decade.”

“Under the deal being discussed,” Reuters continued, “Machinists could receive a bonus payment if the talks result in an agreement approved by the IAM membership, one of the sources said. However, Boeing has warned union leaders that it will open talks with other potential locations if the discussions break down.”

Besides placing final assembly of the revamped jetliner in Everett, the plane’s new carbon-fiber-composite wings would be manufactured elsewhere in the Puget Sound area, Reuters said. That might be a reference to Boeing’s fabrication plant in Frederickson, where composite work is done now for the 787, or it could be some other location. Snohomish County officials hope to interest Boeing in a factory-sized parcel of land on the west side of Paine Field, adjoining Mukilteo.

In July, Boeing CEO Jim McNerney said the company would decide two to six months after the program’s launch where to fabricate the 777X’s wings. Washington officials fear the company will decide to build them somewhere else.

The formal announcement of the 777X program’s launch is expected at the Dubai Air Show Nov. 17-21. Nothing says Boeing has to finalize design and manufacturing plans before the formal program announcement, of course, but those kinds of decisions are no longer trivial to airline buyers of a new jetliner after the debacle of the 787 program, which delivered the first Dreamliners three years later than promised due to problems involving the outsourcing of much design and assembly. The point of unveiling the plane at an air show is to entice potential customers.

Reuters reported that company and union negotiators were under pressure to soon reach a deal. But IAM spokesman Larkin said, “I’m not aware of a deadline other than the decision by Boeing about where the plane will be built.”

Chuck Taylor: 425-339-3429; ctaylor@heraldnet.com.