The Piper PA-31 Navajo is a family of twin-engined utility aircraft designed and built by Piper Aircraft for small cargo and feeder airlines, and as a corporate aircraft. Production ran from 1967 to 1984. It was license-built in a number of Latin American countries.

Development

In 1962, Piper began developing a six- to eight-seat twin-engined corporate and commuter transport aircraft under the project name Inca, at the request of company founder William T. Piper. Looking like a scaled-up PA-30 Twin Comanche, the PA-31 made its first flight on 30 September 1964, and was announced later that year. It is a low-wing monoplane with a conventional tail, powered by two 310 hp Lycoming TIO-540-A turbocharged engines in "tiger shark" cowlings, a feature shared with the Twin Comanche and the PA-23 Aztec. As testing proceeded, two cabin windows were added to each fuselage side and the engines were moved further forward. The PA-31, named "Navajo" after the native American tribe, was certified by the FAA on 24 February 1966, again in mid-1966 with an increase in maximum takeoff weight (MTOW) from 6200 to 6500 lb, and deliveries began in 1967. The PA-31-300 was certified by the FAA in June 1967, the only variant without turbocharged engines: 300 hp Lycoming IO-540-M1A5 engines driving two-bladed propellers. Unofficially, the initial model was referred to as the PA-31-310. Only 14 PA-31-300 were built in 1968 and 1969: the smallest variant production. In January 1966, development of the PA-31P Pressurized Navajo had begun : Piper's first pressurized aircraft. The PA-31P (or PA-31P-425 unofficially) was certified in late 1969. It was powered by 425 hp Lycoming TIGO-541-E engines, had a longer nose, fewer and smaller windows, 25 USgal fuel tanks in the engine nacelles and a one-piece airstair cabin entry door instead of the split pair of doors. MTOW was increased to 7800 lb. The PA-31P was produced from 1970 to 1977. The 1971 Navajo B featured air conditioning, new storage lockers in the rear of the engine nacelles, increased baggage space, a third door next to the cabin doors for easier baggage loading, and an optional separate door for the pilot to enter the cockpit. In September 1972, Piper unveiled the PA-31-350 Navajo Chieftain, a Navajo B stretched by 2 ft for up to ten seats, with more powerful engines and counter-rotating propellers to prevent critical engine handling problems. The Chieftain was powered by 350 hp Lycoming TIO-540 variants, with an opposite-rotation LTIO-540 on the right-hand wing, and MTOW was increased to 7000 lb. Deliveries started in 1973, after a delay due to a flood caused by Hurricane Agnes at Piper's factory in Lock Haven, Pennsylvania. The 1974 PA-31-325 Navajo C/R was base on the Navajo B. The Navajo C/R had 325 hp, lower rated versions of the Chieftain's counter-rotating engines. It was certified in May 1974, and production commenced in the 1975 model year. The Navajo B was also superseded in 1975 by the Navajo C. In May 1981, Piper established its T1000 Airliner Division at its Lakeland, Florida, factory. The PA-31-350T1020 (or T1020) was a PA-31-350 Chieftain optimized for and marketed for the commuter airline market, without the 40 USgal auxiliary fuel tanks in each wing. Up to eleven seats could be fitted, and baggage capacity was reduced from 700 to 600 lb maximum. The first T1020 was delivered in December 1981. The PA-31T3 (T1040) was a hybrid with the PA-31-350T1020 main fuselage, and the nose and tail of the PA-31T1 Cheyenne I. The wings were similar to the Cheyenne I's, but with reduced fuel capacity and baggage lockers in the engine nacelles similar to those of the Chieftain. An optional underbelly cargo pod was also available. The Pratt & Whitney Canada PT6A-11 turboprop engines were the same as those of the Cheyenne I. Deliveries began in July 1982. A T1050 variant was proposed, with a fuselage stretch of 11 ft and seating capacity for 17, but did not proceed. The PA-31P-350 Mojave was also a hybrid, a piston-engined Cheyenne. The Mojave combined the Cheyenne I fuselage with the Chieftain tail. The Chieftain's wings were strengthened, their span was 4 ft wider and the fuel capacity was enlarged to 243 USgal. The engines variants had intercoolers, and the rear part of the nacelles were baggage lockers. The Mojave's MTOW rose by 200 lb to 7200 lb. Certified in 1983, like the T1020 and T1040, the Mojave was produced in 1983 and 1984; combined production with the T1020 and T1040 was below 100 aircraft. Two experimental PA-31-353s were also built in the mid-1980s.

Licensed manufacture

The PA-31 series was manufactured under licence in several countries from kits of parts supplied by Piper. Chincul SACAIFI in Argentina assembled most of the series as the PA-A-31, PA-A-31-325, PA-A-31P and PA-A-31-350 and Aero Industrial Colombiana SA (AICSA) in Colombia assembled PA-31, PA-31-325 and PA-31-350 aircraft. The PA-31-350 Chieftain was also assembled under licence in Brazil by Embraer as the EMB 820C Navajo. In 1984, Embraer subsidiary company Indústria Aeronáutica Neiva began converting Embraer EMB 820Cs by installing Pratt & Whitney Canada PT6 turboprop engines; Neiva called the converted aircraft the Carajá.

Variants

Operators

Civil

The Navajo family is popular with air charter companies, small feeder airlines and commuter air carriers in many countries, and is also operated by private individuals and companies. The PA-31 Navajo was also formerly operated in scheduled passenger airline service in the U.S. in 1968 by Air West, the predecessor of Hughes Airwest which in turn subsequently became an all-jet airline. West Coast Airlines, the predecessor of Air West, began operating the PA-31 Navajo in passenger service in 1967 and called the aircraft the "MiniLiner". West Coast, which was also operating Douglas DC-9-10 jets and Fairchild F-27 turboprops at the time, claimed to be the first "regular airline" to operate the PA-31 Navajo in scheduled service.

Military

Accidents and incidents

Aircraft on display

Specifications (PA-31 Navajo)

Citations