The Piper PA-31T Cheyenne is a turboprop development of the earlier PA-31P Pressurized Navajo. Development Originally, the aircraft was an upgraded version of the Pressurized Navajo equipped with two Pratt & Whitney Canada PT6A-28 turboprop engines. Later, the aircraft was further refined and developed, including aerodynamic improvements and fuselage extensions. The PA-31T led to the development of the PA-42 Cheyenne III and IV. Operators Military operators Mauritanian Air Force United States Department of Defense. Variants PA-31T Cheyenne Initial production version, powered by two 620-shp (462-kW) Pratt & Whitney Canada PT6A-28 turboprop engines. PA-31T-1 Original designation of the PT-31T Cheyenne I. Powered by 500-shp (373-kW) Pratt & Whitney Canada PT6A-II turboprop engines. PA-31T Cheyenne II Improved version, renamed version of original powered by two 620-shp (462-kW) Pratt & Whitney Canada PT6A-28 turboprop engines. PA-31T2 Cheyenne IIXL Stretched version, powered by two 750-shp (559-kW) Pratt & Whitney Canada PT6A-135 turboprop engines. Specifications See also References External links The Piper PA-31T Cheyenne history from Airliners.net Cheyenne 1970s United States civil utility aircraft Low-wing aircraft Aircraft first flown in 1969 Twin-turboprop tractor aircraft