Corporate twin and commuter aircraft. In service since 1965 (Chieftain since 1973). Commuter and airliner development. Basic for a large series of developments that led to Cheyenne 400LS. PA-31-350 Chieftain improved, stretched version for 9 passengers with more powerful counter rotating engines. Production of the Navajo ceased in 1983 (1800 aircraft built) and of the Chieftain in 1984 (1825 aircraft built). Pressurized versions PA-31P Pressurized Navajo and PA-31P-350 Mojave. The PA-31-310 Navajo has 3 square and one rounded cabin window, the PA-31-350 has 4 square cabin windows. Chieftain: Length 10,6 m MTOW 3,200kg.