The Stearman (Boeing) Model 75 is a biplane used as a military trainer aircraft, of which at least 9,783 were built in the United States during the 1930s and 1940s. Stearman Aircraft became a subsidiary of Boeing in 1934. Widely known as the Stearman, Boeing Stearman or Kaydet, it served as a primary trainer for the USAAF, as a basic trainer for the USN (as the NS & N2S), and with the RCAF as the Kaydet throughout World War II. After the conflict was over, thousands of surplus aircraft were sold on the civil market. In the immediate post-war years they became popular as crop dusters and as sports planes.
After World War II, the thousands of PT-17 Stearmans were auctioned off to civilians and former pilots. Many were modified for cropdusting use, with a hopper for pesticide or fertilizer fitted in place of the front cockpit. Additional equipment included pumps, spray bars, and nozzles mounted below the lower wings. A popular approved modification to increase the maximum takeoff weight and climb performance involved fitting a larger Pratt & Whitney R-985 engine and a constant speed propeller.