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The Piper PA-31 Navajo is a family of cabin-class, twin-engined aircraft designed and built by
Piper Aircraft Piper Aircraft, Inc. is a manufacturer of general aviation aircraft, located at the Vero Beach Regional Airport in Vero Beach, Florida, United States and owned since 2009 by the Government of Brunei. Throughout much of the mid-to-late 20th centur ...
for the general aviation market, most using Lycoming engines. It was also license-built in a number of
Latin America Latin America or * french: Amérique Latine, link=no * ht, Amerik Latin, link=no * pt, América Latina, link=no, name=a, sometimes referred to as LatAm is a large cultural region in the Americas where Romance languages — languages derived f ...
n countries. Targeted at small-scale
cargo Cargo consists of bulk goods conveyed by water, air, or land. In economics, freight is cargo that is transported at a freight rate for commercial gain. ''Cargo'' was originally a shipload but now covers all types of freight, including trans ...
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.


Design and development

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 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 In the United States, an American Indian tribe, Native American tribe, Alaska Native village, tribal nation, or similar concept is any extant or historical clan, tribe, band, nation, or other group or community of Native Americans in the Unit ...
, was not certified by the
Federal Aviation Administration The Federal Aviation Administration (FAA) is the largest transportation agency of the U.S. government and regulates all aspects of civil aviation in the country as well as over surrounding international waters. Its powers include air traffic m ...
(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 The maximum takeoff weight (MTOW) or maximum gross takeoff weight (MGTOW) or maximum takeoff mass (MTOM) of an aircraft is the maximum weight at which the pilot is allowed to attempt to take off, due to structural or other limits. The analogous ...
(MTOW) from to . 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 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. The next member of the family was also Piper's first
pressurized {{Wiktionary Pressurization or pressurisation is the application of pressure in a given situation or environment. Industrial Industrial equipment is often maintained at pressures above or below atmospheric. Atmospheric This is the process by ...
aircraft, the PA-31P Pressurized Navajo, certified in late 1969. Development of the PA-31P had begun in January 1966, before the FAA had awarded the PA-31 a
type certificate A type certificate signifies the airworthiness of a particular category of aircraft, according to its manufacturing design (''type design''). It confirms that the aircraft of a new type intended for serial production, is in compliance with applica ...
. The PA-31P was powered by Lycoming TIGO-541-E engines and compared to earlier models had a longer nose, fewer and smaller windows, fuel tanks in the
engine nacelle A nacelle ( ) is a "streamlined body, sized according to what it contains", such as an engine, fuel, or equipment on an aircraft. When attached by a pylon entirely outside the airframe, it is sometimes called a pod, in which case it is attached ...
s and a one-piece
airstair An airstair is a set of steps built into an aircraft so that passengers may board and alight the aircraft. The stairs are often built into a clamshell-style door on the aircraft. Airstairs eliminate the need for passengers to use a mobile st ...
cabin entry door instead of the split pair of doors on the unpressurized models. MTOW was greatly increased at . Also known unofficially as the PA-31P-425, the PA-31P was produced from 1970 to 1977. In 1971, Piper introduced improvements to the PA-31 model. The Navajo B featured air conditioning, increased baggage space achieved by the addition of storage lockers in the rear part of extended nacelles, a third door next to the cabin entry doors to facilitate the loading of baggage, and an optional separate door for the pilot to enter the cockpit. In September 1972, Piper unveiled the PA-31-350 Navajo Chieftain, a stretched version of the Navajo B with more powerful engines and
counter-rotating propellers Counter-rotating propellers, also referred to as CRP, are propellers which spin in opposite directions to each other. They are used on some twin- and multi-engine propeller-driven aircraft. The propellers on most conventional twin-engined a ...
to prevent
critical engine The critical engine of a multi-engine fixed-wing aircraft is the engine that, in the event of failure, would most adversely affect the performance or handling abilities of an aircraft. On propeller aircraft, there is a difference in the remaining ...
handling problems. The fuselage was lengthened by , allowing for up to ten seats in total. Variants of the Lycoming TIO-540 developing were fitted to the Chieftain, with an opposite-rotation LTIO-540 installed on the right-hand wing; MTOW was increased to . The Chieftain's introduction was delayed by a flood at Piper's factory at
Lock Haven, Pennsylvania Lock Haven is the county seat of Clinton County, in the U.S. state of Pennsylvania. Located near the confluence of the West Branch Susquehanna River and Bald Eagle Creek, it is the principal city of the Lock Haven Micropolitan Statistical Area ...
, caused by
Hurricane Agnes Hurricane Agnes in 1972 was the costliest hurricane to hit the United States at the time, causing an estimated $2.1 billion in damage. The hurricane's death toll was 128. The effects of Agnes were widespread, from the Caribbean to Canada, ...
, and deliveries did not commence until 1973. In 1974, Piper used a Navajo B as the basis for developing a new model, the PA-31-325 Navajo C/R. The Navajo C/R had lower-power versions of the counter-rotating engines of the Chieftain, rated at . After certification of the PA-31-325 in May 1974, production commenced in the 1975 model year. The Navajo B was also superseded in the 1975 model year, by the Navajo C version of the PA-31 model. Piper established its T1000 Airliner Division in May 1981 at its
Lakeland, Florida Lakeland is the most populous city in Polk County, Florida, part of the Tampa Bay Area, located along Interstate 4 east of Tampa. According to the 2020 U.S. Census Bureau release, the city had a population of 112,641. Lakeland is a principal c ...
factory. There were two aircraft in the T1000 series. The T1020, or more accurately the PA-31-350T1020 was a PA-31-350 Chieftain optimized for and marketed for the commuter airline market. It featured reduced fuel capacity compared to the standard Chieftain, with the auxiliary fuel tanks in each wing of the Chieftain not fitted to the T1020. It also had reduced baggage capacity ( maximum instead of the Chieftain's maximum) and up to eleven seats. The first T1020 was delivered in December 1981. The second aircraft in the T1000 stable was the T1040 – the PA-31T3 model. The T1040 was a hybrid, featuring the main fuselage of the PA-31-350T1020 with 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 A turboprop is a turbine engine that drives an aircraft propeller. A turboprop consists of an intake, reduction gearbox, compressor, combustor, turbine, and a propelling nozzle. Air enters the intake and is compressed by the compressor. ...
engines were the same as those of the Cheyenne I. Deliveries of the T1040 began in July 1982. A T1050 variant with a fuselage stretch of and seating capacity for 17 was proposed as a factory conversion of existing aircraft, but did not proceed. The last member of the PA-31 family to enter production was the PA-31P-350 Mojave. Like the T1040 the Mojave was a hybrid, but whereas the T1040 was essentially a turboprop Chieftain the Mojave was more or less a piston-engined version of the Cheyenne. The Mojave combined the fuselage of the Cheyenne I with the tail of the Chieftain. The wings were similar to the Chieftain's, but with greater structural strength, a increase in wingspan and greater fuel capacity of . The engines were slightly different variants of the Chieftain's TIO-540 and LTIO-540, being fitted with intercoolers, and like the Chieftain, had baggage lockers on the rear part of the nacelles. The Mojave's MTOW of was higher than the Chieftain's. Certified in 1983, like the T1020 and T1040 the Mojave was introduced at a time of economic
recession In economics, a recession is a business cycle contraction when there is a general decline in economic activity. Recessions generally occur when there is a widespread drop in spending (an adverse demand shock). This may be triggered by various ...
and was produced only in 1983 and 1984; combined production of the T1020, T1040 and Mojave amounted to fewer than 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 Aero is a Greek prefix relating to flight and air. In British English, it is used as an adjective related to flight (e.g., as a shortened substitute for aeroplane). Aero, Ærø, or Aeros may refer to: Aeronautics Airlines and companies * Aero ( ...
(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 Embraer S.A. () is a Brazilian multinational aerospace manufacturer that produces commercial, military, executive and agricultural aircraft, and provides aeronautical services. It was founded in 1969 in São José dos Campos, São Paulo, where i ...
as the EMB 820C Navajo. In 1984, Embraer subsidiary company
Indústria Aeronáutica Neiva Indústria Aeronáutica Neiva is a subsidiary of Embraer which produces airplanes and aircraft components. Its main product is the Embraer EMB 202 Ipanema, the most employed agricultural aircraft in Brazil and the first alcohol-powered airplane. ...
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 The critical engine of a multi-engine fixed-wing aircraft is the engine that, in the event of failure, would most adversely affect the performance or handling abilities of an aircraft. On propeller aircraft, there is a difference in the remaining ...
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. ;PA-31T3 :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
winglet Wingtip devices are intended to improve the efficiency of fixed-wing aircraft by reducing drag. Although there are several types of wing tip devices which function in different manners, their intended effect is always to reduce an aircraft' ...
s. 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.


Operators


Civil

The Navajo family is popular with air charter companies and small feeder airlines in many countries, and is also operated by private individuals and companies.


Military

;Chile *
Chilean Navy The Chilean Navy ( es, Armada de Chile) is the naval warfare service branch of the Chilean Armed Forces. It is under the Ministry of National Defense. Its headquarters are at Edificio Armada de Chile, Valparaiso. History Origins and the War ...
purchased a single PA-31 in 1971. ;Colombia *
Colombian Air Force , "We are the Force" , colours = , colours_label = , march = Colombian Air Force Hymn , mascot = Capitan Paz , anniversaries = 8 November , ...
*
Colombian Navy ) , colors= , march= ''"Viva Colombia, soy marinero"'' , mascot= , battles= Battle of Lake Maracaibo Thousand Days War (Civil war) Colombia-Peru War World War II Korean War Colombian Armed Conflict Operation Atalanta , notable_commanders= José ...
; Dominican Republic *
Dominican Republic Air Force The Air Force of the Dominican Republic ( es, Fuerza Aérea de República Dominicana), is one of the three branches of the Armed Forces of the Dominican Republic, together with the Army and the Navy. History At the end of the United States ...
operates two PA-31s as of December 2018.Hoyle ''Flight International'' 4–10 December 2018, p. 43. ;Finland *
Finnish Air Force , colours = , colours_label = , march = , mascot = , anniversaries = , equipment = 159 , equipment_label ...
operated the PA-31-350 Chieftain in the liaison and light transport role. ;France *
French Navy The French Navy (french: Marine nationale, lit=National Navy), informally , is the maritime arm of the French Armed Forces and one of the five military service branches of France. It is among the largest and most powerful naval forces in t ...
former operator ;Honduras *
Honduran Air Force The Honduras Air Force ( es, Fuerza Aérea Hondureña, sometimes abbreviated to FAH in English) is the air force of Honduras. As such it is the air power arm of the Honduras Armed Forces. History The first Honduras military flying took place ...
operates one PA-31 as of December 2018. ;Kenya * Kenya Air Force operated a Navajo Chieftain in the VIP role. ;Spain *
Spanish Air Force , colours = , colours_label = , march = Spanish Air and Space Force Anthem , mascot = , anniversaries = 10 December , equipment ...
;United Kingdom *
Aeroplane and Armament Experimental Establishment The Aeroplane and Armament Experimental Establishment (A&AEE) was a research facility for British military aviation from 1918 to 1992. Established at Martlesham Heath, Suffolk, the unit moved in 1939 to Boscombe Down, Wiltshire, where its wo ...
former operator


Accidents and incidents

* 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 Ted Stevens Anchorage International Airport is a major airport in the U.S. state of Alaska, located southwest of downtown Anchorage. The airport is named for Ted Stevens, a U.S. senator from Alaska in office from 1968 to 2009. It is include ...
when it collided head-on with
Korean Air Lines Korean Air Co., Ltd. (), operating as Korean Air (Korean Air Lines before 1984), is the flag carrier of South Korea and its largest airline based on fleet size, international destinations and international flights. The present-day Korean Air ...
Flight 084, a
McDonnell Douglas DC-10-30 The McDonnell Douglas DC-10 is an American trijet wide-body aircraft manufactured by McDonnell Douglas. The DC-10 was intended to succeed the DC-8 for long- range flights. It first flew on August 29, 1970; it was introduced on August 5, 1971 ...
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.


Aircraft on display

;Spain * A PA-31P Pressurized Navajo formerly operated by the Spanish Air Force is on display at the Museo del Aire in Madrid.“Piper Navajo”, information placard, Museo del Aire


Specifications (PA-31 Navajo)


See also


References


Citations


Bibliography

* Barnett, Cliff
"Piper looks ahead".
''Flight International'', 24 September 1983, Vol. 124, No. 3881. p.833. * Bonelli, Regis and Pinheiro, Armando Castelar
''New Export Activities in Brazil: Comparative Advantage, Policy or Self-Discovery''
Research Network Working Paper #R-551, Inter-American Development Bank, July 2008. *''Flight Magazine'', Volume 54, No. 11, November 1965. Air Review Publishing Corporation, Dallas, Texas. * Hoyle, Craig. "World Air Forces Directory". ''
Flight International ''Flight International'' is a monthly magazine focused on aerospace. Published in the United Kingdom and founded in 1909 as "A Journal devoted to the Interests, Practice, and Progress of Aerial Locomotion and Transport", it is the world's oldes ...
'', 4–10 December 2018, Vol. 194, No. 5665, pp. 32–60. * Lambert, Mark
"In the air: Piper PA-30 Twin Comanche.
''
Flight International ''Flight International'' is a monthly magazine focused on aerospace. Published in the United Kingdom and founded in 1909 as "A Journal devoted to the Interests, Practice, and Progress of Aerial Locomotion and Transport", it is the world's oldes ...
'', 12 September 1963, Vol. 84, No. 2844, pp. 468–470. * Levy, Howard
"Piper consolidates at Lakeland".
''
Flight International ''Flight International'' is a monthly magazine focused on aerospace. Published in the United Kingdom and founded in 1909 as "A Journal devoted to the Interests, Practice, and Progress of Aerial Locomotion and Transport", it is the world's oldes ...
'', 30 April 1983, Vol. 123, No. 3860, pp. 1152–1153. * Marsh, David
''EUROCONTROL Trends in Air Traffic'' Volume 1: ''Getting to the Point: Business Aviation in Europe''
European Organisation for the Safety of Air Navigation (EUROCONTROL) May 2006. Retrieved 2010-04-11. * Michell, Simon. ''Jane's Civil and Military Aircraft Upgrades 1994–95''. Coulsdon, UK: Jane's Information Group, 1994. .
Piper Aircraft Inc. ''Customer Service Information File'' 2009
retrieved 2010-04-08 *''Piper Airplane Parts Catalog: PA-31 Navajo, PA-31-300 Navajo, PA-31-325 Navajo C/R; September 10, 2009.'' Piper Aircraft Corporation, Manual Part Number 753-703 *''Piper Navajo Information Manual, Revision 9, March 18, 1994.'' Piper Aircraft Corporation, Manual Part Number 761-723 *''Piper Navajo Pilot's Operating Manual, Revision 34, April 22nd 2002.'' Piper Aircraft Corporation, Manual Part Number 761-456 *''Piper T1020 Parts Catalog, Revision 10, September 10, 2009.'' Piper Aircraft Corporation, Manual Part Number 761-775 * Sixma, Herman J. and Jyrki Laukkanen. "Far Northern Air Force: The Finnish Air Arm Today". '' Air International'', July 1986, Vol. 31, No. 1. pp. 7–13. . * Taylor, John W. R. ''Jane's All The World's Aircraft 1976–77''. London: Jane's Yearbooks, 1976, . * Taylor, John W. R. ''Jane's All The World's Aircraft 1982–83''. London: Jane's Yearbooks, 1982, . * Wheeler, Barry C
"World's Air Forces 1979"
''
Flight International ''Flight International'' is a monthly magazine focused on aerospace. Published in the United Kingdom and founded in 1909 as "A Journal devoted to the Interests, Practice, and Progress of Aerial Locomotion and Transport", it is the world's oldes ...
'', 4 August 1979, Vol. 116, No. 3672. pp. 333–386. {{Swedish military aircraft designations 1960s United States civil utility aircraft Aircraft first flown in 1964 Low-wing aircraft
Navajo The Navajo (; British English: Navaho; nv, Diné or ') are a Native American people of the Southwestern United States. With more than 399,494 enrolled tribal members , the Navajo Nation is the largest federally recognized tribe in the United ...
Twin piston-engined tractor aircraft