Piper Navajo

PA-31
Piper PA-31 Navajo
Role	Civil utility aircraft
Manufacturer	Piper Aircraft
First flight	30 September 1964
Introduction	30 March 1967
Status	Active service
Produced	1967–1984
Number built	3942
Variants	Piper PA-31T Cheyenne

The Piper PA-31 Navajo is a family of cabin-class, twin-engined aircraft designed and built by Piper Aircraft for the general aviation market, most using Lycoming engines. It was also license-built in a number of Latin American countries. Targeted at small-scale cargo and feeder liner operations and the corporate market, the aircraft was a success. It continues to prove a popular choice, but due to greatly decreased demand across the general aviation sector in the 1980s, production of the PA-31 ceased in 1984.

At the request of company founder William T. Piper, Piper began development of a six- to eight-seat twin-engined corporate and commuter transport aircraft in 1962 under the project name Inca. The type, now designated the PA-31 and looking like a scaled-up Twin Comanche, was officially announced in late 1964 after its first flight on 30 September that year. It was a low-wing monoplane with a conventional tail, powered by two 310 hp (231 kW) Lycoming TIO-540-A turbocharged engines in so-called "tiger shark" cowlings, a feature shared with the Twin Comanche and also the PA-23 Aztec. As testing proceeded two cabin windows were added to each side of the fuselage and the engines moved further forward. The PA-31, now named "Navajo" after a Native American tribe, was not certified by the Federal Aviation Administration (FAA) until 24 February 1966, and deliveries did not begin until the following year, after the type was recertified in mid-1966 with an increase in maximum takeoff weight (MTOW) from 6,200 lb (2,812 kg) to 6,500 lb (2,948 kg).

The PA-31-300 was the next model, certified by the FAA in June 1967. This model was the only one of the PA-31 series not to have turbocharged engines. A pair of 300 hp (224 kW) Lycoming IO-540-M1A5 engines were fitted to the PA-31-300, driving two-bladed propellers. Following the introduction of the PA-31-300 the turbocharged model began to be known unofficially as the PA-31-310. The PA-31-300 was only produced in 1968 and 1969 and had the smallest production total for any PA-31 series model, with only 14 aircraft built.

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