MONTREAL -- Air Canada has signed a letter of intent to purchase 45 of Bombardier's CS300 aircraft with options for an additional 30 planes.

Based on the list price of the CS300, Bombardier (TSX:BBD.B) says a firm order would be worth about $3.8 billion.

Once a firm purchase agreement is in place, Bombardier says Air Canada (TSX:AC) will become the first mainline, international North America-based carrier for the C Series family of aircraft. Deliveries are scheduled to begin in 2019.

With this agreement, Bombardier says it now has orders and commitments for a total of 678 C Series planes.

The agreement with Air Canada was announced by Bombardier at the same time it said it would cut its workforce by 7,000 positions over two years, including 2,000 contractors.

The job losses will be partly offset by hiring in certain areas, including the C Series project.