The federal government took a step Monday toward buying about two dozen helicopters for the Canadian Coast Guard's fleet, although it will take years before the aircraft are in service.

The government posted on its MERX tendering website a letter of interest that is aimed at the aerospace industry.

It's the first of a series of steps that need to be taken to replace aging choppers in the coast guard's service.

The government intends to buy as many as 22 helicopters to replace aircraft that patrol coastlines around the country.

As well, two new helicopters are to be earmarked for work aboard the polar icebreaker John G. Diefenbaker.

The government said in a news release that it expects to take about five years to complete the procurement, which will also involve the purchase of a flight simulator.

Officials are expected to start meeting with industry soon on the scope of the project.

"Helicopter air support is a crucial component to the delivery of coast guard services and the maintenance of public safety," Fisheries Minister Keith Ashfield said in a statement.

"Renewing the Canadian Coast Guard fleet of helicopters will stimulate economic growth in the aerospace industry, as well as create a variety of jobs and business opportunities."

The new helicopters are expected to be in service for three decades.

The coast guard uses helicopters for several purposes, primarily to support the safety of marine traffic.