The Piper PA-31 Navajo is a family of twin-engined low-wing tricycle gear 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 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 , and deliveries began in 1967.

The PA-31-300 was certified by the FAA in June 1967, the only variant without turbocharged engines: 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 Lycoming TIGO-541-E engines, had a longer nose, fewer and smaller windows, 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 . 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 for up to ten seats, with more powerful engines and counter-rotating propellers to prevent critical engine handling problems. The Chieftain was powered by Lycoming TIO-540 variants, with an opposite-rotation LTIO-540 on the right-hand wing, and MTOW was increased to . 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 based on the Navajo B. The Navajo C/R had , 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 auxiliary fuel tanks in each wing. Up to eleven seats could be fitted, and baggage capacity was reduced from 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 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 wider and the fuel capacity was enlarged to . The engines variants had intercoolers, and the rear part of the nacelles were baggage lockers. The Mojave's MTOW rose by to . 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

Initial production version, also known unofficially as the PA-31-310. PA-31-300 Navajo Variant of the Navajo with normally aspirated engines; 14 built. PA-31 Navajo B Marketing name for 1971 improved variant with Lycoming TIO-540-E turbo-charged piston engines, new airconditioning and optional pilot access door and optional wide utility door.Peperell 1987, pp. 179-201 PA-31 Navajo C Marketing name for 1974 improved variant with Lycoming TIO-540-A2C engines and other minor improvements. PA-31P Pressurized Navajo Pressurized version of the PA-31 Navajo, powered by two 425-hp (317-kW) Lycoming TIGO-541-E1A piston engines.

Referred to as the "Navajo C/R" for Counter-rotating; variant of Navajo with counter-rotating engines introduced with the PA-31-350 Chieftain. Lycoming TIO-540 / LTIO-540 engines

Stretched version of the Navajo with more powerful 350-hp (261-kW) counter-rotating engines (a Lycoming TIO-540 and a Lycoming LTIO-540) to eliminate critical engine issues. PA-31P-350 Mojave Piston-engined variant of the PA-31T1 Cheyenne I; 50 aircraft built. PA-31-350T1020 Also known as the T1020/T-1020; variant of the PA-31-350 Chieftain optimised for commuter airline use, with less baggage and fuel capacity and increased seating capacity (nine passengers). First flight September 25, 1981. 21 built.Taylor 1982, pp. 450–451.

Also known as the T1040/T-1040; turboprop-powered airliner with fuselage of the PA-31-350T1020, and wings, tail and Pratt & Whitney Canada PT6A-11 engines of PA-31T Cheyenne. First flight July 17, 1981. 24 built.Taylor 1982, p. 451. PA-31-353 Experimental version of PA-31-350; two built.

T1050 Unbuilt airliner variant with fuselage lengthened by compared to the PA-31-350. EMB 820C Version of Chieftain built under license by Embraer in Brazil. Neiva Carajá Turboprop conversion of EMB 820C, fitted with two Pratt & Whitney Canada PT6A-27 engines flat-rated to 550shp. The Carajá's MTOW of was more than that of the Chieftain.

Colemill Panther Re-engined Navajo with Lycoming TIO-540-J2B engines, four-blade Hartzell "Q-Tip" propellers and optional winglets. Conversion designed by Colemill Enterprises of Nashville, Tennessee.Michell 1994, p. 305. The supplemental type certificates (STCs) were subsequently sold to Mike Jones Aircraft Sales, which continues to convert PA-31, PA-31-325 and PA-31-350 variants with Colemill-developed features.

+Number builtTypeBuiltLocationPA-311785Lock HavenLakelandPA-31-3501825Lock HavenLakelandT-102021LakelandPA-31-3532LakelandPA-31P259Lock HavenPA-31P-35050Lock HavenTotal3942

Operators

Civil

Philippine Coast Guard: 1 Unit of PA-31-325 serial PCG-221 entered service August 2025.https://scontent.flgp1-1.fna.fbcdn.net/v/t39.30808-6/534804856_1210314810899540_5472684222142003733_n.jpg?_nc_cat=111&ccb=1-7&_nc_sid=127cfc&_nc_ohc=9AWPY7k9HeUQ7kNvwFE_80a&_nc_oc=AdlKn8huVE2P0-NNY2lBBmX9krqxF4_y1YXWJMjHNNWEKYc4gBJcwAi2cJC9_0bnhug&_nc_zt=23&_nc_ht=scontent.flgp1-1.fna&_nc_gid=QI374vOGYTNFXob_SyBDlQ&oh=00_AfV5YDxoBq7wXBeuNuZ6oC0PcsRP7027ajhcYSDRZv30ig&oe=68AB1942

Sevenair Air Services

HM Coastguard (2Excel Aviation)

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

Antigua and Barbuda Defence Force Air Wing operates (2023) one PA-31 with one more "unserviceable" aircraft in store.

Chilean Navy purchased a single PA-31 in 1971.

Colombian Air Force Colombian Navy

Dominican Republic Air Force operates two PA-31s as of December 2018.Hoyle Flight International 4–10 December 2018, p. 43.

Finnish Air Force operated the PA-31-350 Chieftain in the liaison and light transport role.Sixma and Laukkanen Air International July 1986, p. 12.

French Navy former operator

Honduran Air Force operates one PA-31 as of December 2018.

Kenya Air Force operated a Navajo Chieftain in the VIP role.Wheeler Flight International 4 August 1979, p. 364.

Spanish Air Force

Aeroplane and Armament Experimental Establishment former operator

Accidents and incidents July 13, 1972: An Ansett Australia Piper PA-31 Navajo aircraft, registered as VH-CIZ, crashed near Golden Grove shortly after departing Adelaide for a charter flight to Moomba Airport. All eight people on board, including the pilot and seven passengers, were killed. December 18, 1979: A Piper PA-31 Navajo light plane working a courier service crashed at Halifax airport, killing two and destroying many documents detailing transactions from 59 banks in Prince Edward Island and Cape Breton. December 3, 1983: SouthCentral Air Flight 59, a PA-31-350 registered N35206, carrying eight passengers and one pilot, was on the takeoff roll at Anchorage International Airport when it collided head-on with Korean Air Lines Flight 084, a McDonnell Douglas DC-10-30 freighter HL7339. The Piper struck the DC-10's left and center main landing gear and three passengers sustained minor injuries; the DC-10 overran the runway and the three crew suffered serious injuries. Investigators determined that the Korean Air Lines pilot had become disoriented taxiing in fog, failed to follow correct procedures and confirm his position, and accidentally initiated takeoff from the wrong runway. Both aircraft were severely damaged and were written off. October 14, 1984: Wapiti Aviation Flight 402 collided with terrain while landing at High Prairie Airport killing six of the 10 occupants onboard including Canadian politician Grant Notley. January 11, 1987: An Eagle Air Piper Chieftain with registration TF-ORN, crashed in the ocean outside of Skutulsfjörður while on approach to Ísafjörður Airport, in bad weather, killing the pilot. April 27, 1994: A Piper PA-31-350 Navajo Chieftain, registration N990RA, operated by Action Air Charters, overshot the 6-24 runway at Sikorsky Memorial Airport, Stratford, Connecticut, and struck a fence, killing eight of the nine aboard.National Transportation Safety Board, Aviation Accident Report NTSB/AAR-94/08, Impact With Blast Fence Upon Landing Rollout, Action Air Charters Flight 990, Piper PA-31-350, N990RA, Stratford, Connecticut, April 27, 1994. Adopted December 13, 1994.