Canada's prime minister Justin Trudeau has warned that his country "won't do business" with Boeing if the American airframer continues a trade complaint against Bombardier and its CSeries commercial aircraft.

Trudeau's comments, made on 18 September, mark the latest salvo in a trade dispute between Boeing and Bombardier, and throw additional uncertainty on Canada's plan to buy 18 Boeing F/A-18 Super Hornet fighters.

"We have obviously been looking at the Super Hornet aircraft from Boeing as a potential significant procurement of… new fighter jets, but we won't do business with a company that is trying to sue us and put our aerospace workers out of business," Trudeau said during a press conference with UK prime minister Theresa May.

Trudeau was referring to Boeing's complaint to US trade officials in April that a heavily subsidised Bombardier sold CSeries aircraft to Delta Air Lines at artificially low prices.

The US Department of Commerce has set 25 September as the date it intends to issue a preliminary decision on whether to impose countervailing duties against Bombardier's CSeries.

Boeing, in its petition, estimated that Boeing had sold 75 CS100s to Delta in 2016 at a price of about $20 million per aircraft. Those aircraft cost some $33 million to produce, estimates Boeing.

The deal negatively impacted American industry by depressing prices for the competing 737-700 and 737 Max, Boeing argues.

Bombardier has denied the claims, arguing that the CS100, with about 108 seats, does not even compete with the 737s, which carry between 126 and 138 seats.

Bombardier says Boeing exited the roughly-100-seat market when it stopped producing 717s a decade ago.

"Boeing is not suing Canada," the company tells FlightGlobal in response to Trudeau's comments.

"This is a commercial dispute with Bombardier, which has sold its CSeries airplane in the United States at absurdly low prices, in violation of US and global trade laws," Boeing says. "This is a classic case of dumping, made possible by a major injection of public funds… But competition and sales must respect globally accepted trade law.”

Bombardier issued a media release on 18 September reiterating its position.

"Delta ordered the CSeries because Boeing stopped making an aircraft of the size Delta needed years ago," says Bombardier. "Boeing's self-serving actions threaten thousands of aerospace jobs around the world, including thousands of UK and US jobs and… purchases from the many UK and US suppliers."

During the press conference, UK prime minister May also spoke in support of Bombardier, saying Boeing's petition threatened jobs at Bombardier's facility in Northern Ireland, where the company makes wings for the CSeries.

May says she intends to speak to US president Donald Trump in the coming days about the dispute.

"I will be impressing on him the significance of Bombardier to the United Kingdom and, in particular, to jobs in Northern Ireland. I want to see a resolution that protects those jobs in Northern Ireland," May says.

Source: Cirium Dashboard