The Trudeau government has formally asked Washington to facilitate the sole-source purchase of a handful of Super Hornet jet fighters for the air force.

Public Works and Procurement Services, in a statement, said a letter of request was submitted to the U.S. Department of Defence on Monday that outlined Canada's requirements, capabilities, schedule and expected economic benefits.

The Liberal government has been quietly negotiating the deal to buy 18 of the jets since early in the year after announcing last fall that the military needed an interim set of fighters until the entire fleet of aging CF-18s is retired.

Since the Liberals have chosen to buy through the U.S. government, rather than a commercial deal, federal officials say they've made it clear to Washington that they intend to invoke the "Industrial and Technological Benefits Policy."

That means suppliers will be expected to make investments in Canadian businesses equal to 100 per cent of the contract value.

It's an attempt to ensure that aerospace companies in this country can participate in the procurement.

"This will ensure that the potential procurement of interim aircraft will help grow Canada's aerospace and defence sector, create high-value jobs and support Canadian innovation," the statement said.

Under the rules of foreign military sales, the benefits will have to be negotiated.

Earlier this winter, Boeing officials said the company was prepared to deliver an offset equal to the purchase price the U.S. navy pays, roughly $85 million ($65 million US) per aircraft.

A U.S. navy flight line technician prepares a Super Hornet for flight at Air Station Oceana, Virginia Beach, Va., on Jan. 26.

It's now up to the Pentagon to negotiate with Boeing and come up with an official proposal for Canada.

The deal will also have to be approved by the U.S. Congress.

The statement says it will be the fall of this year before Canadian officials can review the proposal and potential costs.

"We will assess whether an interim Super Hornet fleet purchase will help ensure Canada remains a credible and dependable ally for many years to come," Defence Minister Harjit Sajjan said in a statement on Tuesday.

Up to $7B price tag

One set of internal estimates at National Defence, shared with CBC News by anonymous sources in January, suggested the price tag for taxpayers could run between $5 billion and $7 billion over the lifetime of the aircraft.

Boeing officials, in an interview at that time, suggested a contract would take up to year to negotiate, but that Canada had already signalled it would like to see the first aircraft arrive in 2019, which would coincide with the next election.

Given that the company already has contracts from the U.S. navy and Kuwait, Boeing's vice-president of the FA-18 program, Dan Gillian, said the company is looking at how production of Canadian jets can be slotted alongside existing orders.

Additionally, the Liberal government will have to negotiate an in-service support contract and consider buying training simulators for both pilots and perhaps mechanics.