In 1915, U.S.-based Curtiss-Wright began aircraft assembly in Toronto. In 1928, Pratt & Whitney established engine repair and overhaul (R&O) facilities in Canada. U.K.-based firms such as de Havilland and Vickers began aircraft assembly and R&O operations in Canada on a limited scale. Other important aircraft manufacturing and R&O operations developed at a number of plants owned by firms primarily involved in the production of other types of transportation equipment, such as rail cars (Canadian Car & Foundry in Fort William and National Steel Car at Malton), ships (Canadian Vickers in Montreal) and trams and buses (Ottawa Car). During the 1930s Canadian-based design and/or aircraft manufacturing capabilities were also developed at Fleet Aircraft in Fort Erie and Noorduyn in Montreal.

World War II
During World War II the Canadian industry's manufacturing capacity was expanded rapidly to undertake licensed production of over 10,000 military aircraft to meet Allied operational and training needs. The Canadian government became actively involved in restructuring the wartime aircraft industry, forming Federal Aircraft in 1940, taking over National Steel Car (renamed Victory Aircraft) in 1943 and Canadian Vickers (renamed Canadair) in 1944. In the aftermath of the war, a number of aircraft manufacturers, including Boeing in Vancouver and Fairchild in Montreal, shut down their Canadian facilities. The two Crown corporations formed during the war were privatized, with Victory (renamed Avro) purchased by A.V. Roe of the United Kingdom and Canadair acquired by General Dynamics of the United States.
Quoted from: http://strategis.ic.gc.ca/SSG/ad02641e.html