The federal government has taken a step towards buying up to 24 helicopters for the coast guard. Ottawa has issued a letter of interest for the aerospace sector in order to begin attracting possible contractors for the procurement. The helicopter project aims to procure the choppers over the next five years for the coast guard fleet and to support missions of a Polar-class icebreaker named after former prime minister John G. Diefenbaker. That ship is expected to be built in 2017. The federal government says the new helicopters are expected to have a service life of about 30 years. There is no precise cost estimate.