SEATTLE — If the Boeing strike drags on for more than three months, there could be long-lasting harm to the country's exports, economists said.

By dollar value, Boeing Co. ranks among the nation's top industrial exporters. Exports are one of the few bright spots in the nation's economy. But that could change if the walkout runs beyond three months and customers are spooked, eventually turning to Chicago-based Boeing's European rival, Airbus S.A.S., for future orders of commercial passenger and cargo jets.

Few expect the strike to last that long. Besides, analyst Cai von Rumohr at Cowen and Co. noted yesterday that Airbus has a four- to seven-year backlog and thus is in no position to take any of Boeing's orders in the near term.

The last two strikes by the International Association of Machinists and Aerospace Workers at Boeing's commercial aircraft operations lasted 24 days in 2005 and 69 days in 1995. The latter was the longest at Boeing since a 140-day strike in 1948.

In general, Boeing receives about 50 to 60 percent of the purchase price on delivery, the rest coming earlier in payments negotiated separately with each order, said Richard Aboulafia, vice president and analyst for the Teal Group in Fairfax, Va.

List prices range from $50 million to $57 million for a 737-600, to $285.5 million to $300 million for a 747-8.

Boeing failed to deliver more than two dozen planes on schedule during the walkout three years ago. This time, with about a seven-year order backlog and a scheduled delivery rate of more than 40 planes a month, the company stands to lose $100 million to $110 million a day in deferred revenue by most analysts' estimates.

"If it's a month long, you'll definitely see a blip" in trade gap figures, Aboulafia said. "Two months isn't the end of the world," but four months would make customers wonder, " 'Why can't they settle it? What's going on?' "

Even in the economy of the greater Seattle area, home to 25,000 of the 27,000 electricians, painters, mechanics, riveters and other hourly production workers represented by the Machinists, a one-month strike "really has a negligible impact," said Dick Conway of Dick Conway & Associates, an economist and regional economic forecaster.

Up to three months or so, Conway said, buyers are likely to cut Boeing the same kind of slack the manufacturer has shown in accepting delays and renegotiating terms for airlines during severe downdrafts in air travel.

Yesterday, Boeing spokesman Tim Healy and Connie Kelliher, a spokeswoman for Machinists District Lodge 751 in Seattle, said both sides were ready to resume negotiations at any time, but no talks were scheduled.

Union members voted 80 percent on Wednesday to reject Boeing's last contract offer and 87 percent to go on strike the next day. Both sides agreed to extend the old contract for 48 hours in a last-ditch bargaining effort with a federal mediator at the table.

The strike began Saturday morning after that deadline expired without an agreement.

Peter Morici, an international business professor at the Robert H. Smith School of Business at the University of Maryland, said revenue — and exports — lost during the strike will be made up once the walkout is settled and aircraft deliveries resume, much as workers will again be receiving regular paychecks.

"It only delays the exports unless it continues so long that they lose orders" for aircraft in the future, Morici said. "It takes a long time before that affects the balance of trade."

Airbus also has strong unions that have shown no hesitation to strike, waging a number of protest walkouts over issues ranging from disparate treatment of French and German workers in April, to unhappiness with drastic cuts in bonuses a year earlier.

"Unless Airbus can offer itself as a more reliable performer, the strike is not going to make a lot of difference," Morici said.

The strike's impact on exports will likely be considerably less than from Boeing's continued outsourcing of work formerly done by the Machinists to subcontractors, particularly foreign companies, a key issue in the walkout, said Ken Jacobs, chairman of the University of California Labor Center in Berkeley.

"Removing jobs permanently from the area — that has a much more serious long-term impact," Jacobs said.