The CSeries received a significant endorsement last year, when Delta Air Lines ordered 75 of the planes, which are slightly smaller than the A320 or Boeing’s 737. Although Boeing did not bid on Delta’s purchase, it undertook a trade action against Bombardier, arguing that loans and investments in the CSeries by the governments of Canada and Quebec would allow the company to sell the planes at artificially low prices. Bombardier has rejected that claim. Noting that Boeing has received assistance from the United States, it called its competitor’s complaint “pure hypocrisy.”
Boeing’s trade action has angered the government of Prime Minister Justin Trudeau, which immediately suspended plans to buy fighter jets from Boeing worth about 6 billion Canadian dollars. The wings of the CSeries are made at a Bombardier factory in Northern Ireland, prompting Theresa May, the British prime minister, to join Mr. Trudeau in urging President Trump to ask Boeing to drop its case. But they have not found a receptive audience in Washington.
Wilbur Ross, the secretary of commerce, declined to comment, saying the government did not yet know enough about the new development to determine its impact.
The Commerce Department announced last month that it would impose preliminary duties of 219.63 percent on the sale price of CSeries planes to offset the subsidies that Bombardier had received. On Oct. 6, it announced an additional 79.82 percent duty for selling the aircraft at an artificially low price.
The Commerce Department will announce final rulings on the duties in December, then the United States International Trade Commission will uphold or overturn the tariffs early next year.
In a statement, Boeing called the announcement “a questionable deal between two heavily state-subsidized competitors to skirt the recent findings of the U.S. government.”
“Our position remains that everyone should play by the same rules for free and fair trade to work,” the company said.
The assembly line in Alabama may solve Bombardier’s tariff problem with the CSeries, but it could raise political tensions in Quebec, which had bailed out the program through an investment of about 1 billion Canadian dollars. But Mr. Bellemare said that the sales power of Airbus should mean that far more CSeries airplanes will be produced, which will guarantee — and possibly expand — employment at the factory northwest of Montreal that now builds the plane.