Pratt & Whitney Canada PT6

The PT6 is a family of lightweight free-turbine turboprop engines from Pratt & Whitney Canada, designed from 1958 by a small team of engineers under engineering manager Dick Guthrie. It first flew on 30 May 1961 in the nose of a converted Beech 18 test aircraft and entered service in 1964, after its first production model, the PT6A-6, was certificated in December 1963. A gas generator with its accessory gearbox feeds a separate power turbine, so the starter turns only the gas generator, and in most airframes the engine is mounted back to front with its intake at the rear. The PT6A turboprops span roughly 580 to 1,940 shaft horsepower, the PT6B and PT6C variants power helicopters, and derived engines serve as auxiliary power units and in racing cars. More than 51,000 had been built by November 2015.