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Piper PA-31 Navajo

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PA-31
Piper PA-31 Navajo, with aftermarketwingletsinstalled
Role Utility aircraft
Manufacturer Piper Aircraft
First flight 30 September 1964[1]
Introduction 30 March 1967
Status Active service
Produced 1967–1984[2]
Number built 3942[3]
Variants Piper PA-31T Cheyenne

ThePiper PA-31 Navajois a family of twin-enginedutility aircraftdesigned and built byPiper Aircraftfor smallcargoandfeeder airlines,and as acorporate aircraft.Production ran from 1967 to 1984. It was license-built in a number ofLatin Americancountries.

Development[edit]

Early Navajo with two-bladed propellers and two-part entry door

In 1962, Piper began developing a six- to eight-seat twin-engined corporate and commuter transport aircraft under the project nameInca,at the request of company founderWilliam T. Piper.[2][4]Looking like a scaled-upPA-30 Twin Comanche,the PA-31 made its first flight on 30 September 1964, and was announced later that year.[1][4]It is a low-wing monoplane with a conventional tail, powered by two 310 hp (231 kW)Lycoming TIO-540-Aturbocharged engines in "tiger shark" cowlings, a feature shared with the Twin Comanche and thePA-23 Aztec.[4][5][6]

As testing proceeded, two cabin windows were added to each fuselage side and the engines were moved further forward.[6][7]The PA-31, named "Navajo"after the native American tribe, wascertifiedby theFAAon 24 February 1966, again in mid-1966 with an increase inmaximum takeoff weight(MTOW) from 6,200 to 6,500 lb (2,812 to 2,948 kg), and deliveries began in 1967.[2][8]

The PA-31-300 was certified by the FAA in June 1967, the only variant withoutturbochargedengines: 300 hp (224 kW) Lycoming IO-540-M1A5 engines driving two-bladed propellers.[8]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.[2][9]

Pressurized PA-31P with fewer and smaller windows

In January 1966, development of the PA-31P Pressurized Navajo had begun: Piper's firstpressurizedaircraft.[10]The PA-31P (or PA-31P-425 unofficially) was certified in late 1969.[11]It was powered by 425 hp (317 kW)Lycoming TIGO-541-Eengines, had a longer nose, fewer and smaller windows, 25 US gal (95 L) fuel tanks in theengine nacellesand a one-pieceairstaircabin entry door instead of the split pair of doors.[2][11][10]MTOW was increased to 7,800 lb (3,538 kg).[11]The PA-31P was produced from 1970 to 1977.[2]

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.[3][12]

The PA-31-350 Chieftain, stretched by 2 ft (61 cm)

In September 1972, Piper unveiled the PA-31-350 Navajo Chieftain, a Navajo B stretched by 2 ft (61 cm) for up to ten seats, with more powerful engines andcounter-rotating propellersto preventcritical enginehandling problems.[8][13]The Chieftain was powered by 350 hp (261 kW) Lycoming TIO-540 variants, with an opposite-rotation LTIO-540 on the right-hand wing, and MTOW was increased to 7,000 lb (3,175 kg).[8]Deliveries started in 1973, after a delay due to a flood caused byHurricane Agnesat Piper's factory inLock Haven, Pennsylvania.[13][14]

The 1974 PA-31-325 Navajo C/R was base on the Navajo B.[15]The Navajo C/R had 325 hp (242 kW), lower rated versions of the Chieftain's counter-rotating engines.[8]It was certified in May 1974, and production commenced in the 1975 model year.[15]The Navajo B was also superseded in 1975 by the Navajo C.[15]

In May 1981, Piper established its T1000 Airliner Division at itsLakeland, Florida,factory.[16]The PA-31-350T1020 (or T1020) was a PA-31-350 Chieftain optimized for and marketed for the commuter airline market, without the 40 US gal (151 L) auxiliary fuel tanks in each wing.[8]Up to eleven seats could be fitted, and baggage capacity was reduced from 700 to 600 lb (318 to 272 kg) maximum.[8]The first T1020 was delivered in December 1981.[17]

The PA-31T3 (T1040) was a hybrid with the PA-31-350T1020 main fuselage, and the nose and tail of thePA-31T1 Cheyenne I.[18]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.[11]An optional underbelly cargo pod was also available.[11][18]ThePratt & Whitney Canada PT6A-11turbopropengines were the same as those of the Cheyenne I.[11]Deliveries began in July 1982.[17]A T1050 variant was proposed, with a fuselage stretch of 11 ft 6 in (3.51 m) and seating capacity for 17, but did not proceed.[18]

Pressurized PA-31P-350 Mojave

The PA-31P-350 Mojave was also a hybrid, a piston-engined Cheyenne.[19]The Mojave combined the Cheyenne I fuselage with the Chieftain tail.[19]The Chieftain's wings were strengthened, their span was 4 ft (1.2 m) wider and the fuel capacity was enlarged to 243 US gal (920 L).[19]The engines variants hadintercoolers,and the rear part of the nacelles were baggage lockers.[19]The Mojave's MTOW rose by 200 lb (91 kg) to 7,200 lb (3,266 kg).[8][11]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.[11][14][18]Two experimental PA-31-353s were also built in the mid-1980s.[14]

Licensed manufacture[edit]

The PA-31 series was manufactured under licence in several countries from kits of parts supplied by Piper.[20][21]Chincul SACAIFIin Argentina assembled most of the series as the PA-A-31, PA-A-31-325, PA-A-31P and PA-A-31-350 andAero Industrial Colombiana SA(AICSA) in Colombia assembled PA-31, PA-31-325 and PA-31-350 aircraft.[22]The PA-31-350 Chieftain was also assembled under licence in Brazil byEmbraeras the EMB 820C Navajo.[23][21]In 1984, Embraer subsidiary companyIndústria Aeronáutica Neivabegan converting Embraer EMB 820Cs by installingPratt & Whitney Canada PT6turboprop engines; Neiva called the converted aircraft the Carajá.[24]

Variants[edit]

commuter cabin
PA-31 Navajo
Initial production version, also known unofficially as the PA-31-310.[2][8]
PA-31-300 Navajo
Variant of the Navajo with normally aspirated engines; 14 built.[2][9]
PA-31 Navajo B
Marketing name for 1971 improved variant with 310 hp (231 kW)Lycoming TIO-540-Eturbo-charged piston engines, new airconditioning and optional pilot access door and optional wide utility door.[3]
PA-31 Navajo C
Marketing name for 1974 improved variant with 310 hp (231 kW)Lycoming TIO-540-A2Cengines and other minor improvements.[3]
PA-31P Pressurized Navajo
Pressurized version of the PA-31 Navajo, powered by two 425-hp (317-kW) Lycoming TIGO-541-E1A piston engines.[2][11]
PA-31-325 Navajo
Referred to as the "Navajo C/R" for Counter-rotating; variant of Navajo with counter-rotating engines introduced with the PA-31-350 Chieftain. 325 hp (242 kW) Lycoming TIO-540 / LTIO-540 engines
PA-31-350 Chieftain
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 eliminatecritical engineissues.
PA-31P-350 Mojave
Piston-engined variant of thePA-31T1 Cheyenne I;50 aircraft built.[11]
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.[8][25][26]
PA-31T3
Also known as the T1040/T-1040; turboprop-powered airliner with fuselage of the PA-31-350T1020, and wings, tail andPratt & Whitney Canada PT6A-11 engines ofPA-31T Cheyenne.First flight July 17, 1981. 24 built.[14][27]
PA-31-353
Experimental version of PA-31-350; two built.[14]
license-built EMB 820C
T1050
Unbuilt airliner variant with fuselage lengthened by 11 ft 6 in (3.51 m) 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 twoPratt & Whitney Canada PT6A-27engines flat-rated to 550shp. The Carajá's MTOW of 8,003 pounds (3,630 kg) was 1,000 pounds (454 kg) more than that of the Chieftain.[24]
Panther conversion with four-blade propellers
Colemill Panther
Re-engined Navajo with 350 hp (261 kW)Lycoming TIO-540-J2Bengines, four-blade Hartzell "Q-Tip" propellers and optionalwinglets.Conversion designed by Colemill Enterprises of Nashville, Tennessee.[28][29]Thesupplemental 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.[30][31]
Number built[3]
Type Built Location
PA-31 1785 Lock Haven
Lakeland
PA-31-350 1825 Lock Haven
Lakeland
T-1020 21 Lakeland
PA-31-353 2 Lakeland
PA-31P 259 Lock Haven
PA-31P-350 50 Lock Haven
Total 3942

Operators[edit]

Civil[edit]

The Navajo family is popular with air charter companies, small feeder airlines and commuter air carriers in many countries,[citation needed]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 ofHughes Airwestwhich in turn subsequently became an all-jet airline.[32][33]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".[34]West Coast, which was also operatingDouglas DC-9-10jets andFairchild F-27turboprops at the time, claimed to be the first "regular airline" to operate the PA-31 Navajo in scheduled service.[35][36]

Military[edit]

Chile
Colombia
Dominican Republic
Finland
France
Honduras
Kenya
Spain
United Kingdom

Accidents and incidents[edit]

  • December 3, 1983:SouthCentral Air Flight 59,a PA-31-350 registeredN35206,carrying eight passengers and one pilot, was on the takeoff roll atAnchorage International Airportwhen it collided head-on withKorean Air LinesFlight 084, aMcDonnell Douglas DC-10-30freighterHL7339.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.[45]
  • May 31, 2000: Whyalla Airlines Flight 904 was a scheduled commuter flight, operated by a Piper PA-31 Navajo whichcrashed while attempting to ditchin theSpencer Gulf,South Australiaafter suffering failures of both engines on the evening of 31 May 2000. All 8 people on board the aircraft were killed as a result of the accident. The findings of a subsequent investigation by theAustralian Transport Safety Bureauhighlighting the airline's operating procedures as a key factor leading to the accident were later overturned after they were contradicted by evidence presented at acoronial inquiryinto the deaths of those on board the flight.[46]The safety implications arising from the accident were subject to a recall by engine manufacturerTextron Lycomingwhich saw close to 1000 aircraft grounded worldwide while defects were rectified at an estimated cost of$A66 million. Australia's aviation regulator, theCivil Aviation Safety Authorityalso mandated lifejackets be carried on all aircraft operating over water after the crash.[47]

Aircraft on display[edit]

Spain
  • A PA-31P Pressurized Navajo formerly operated by the Spanish Air Force is on display at theMuseo del Airein Madrid.[43]

Specifications (PA-31 Navajo)[edit]

cockpit
PA-31-350 Navajo Chieftain

Data fromJane's All The World's Aircraft 1976–77[48]

General characteristics

  • Crew:1 or 2
  • Capacity:5 to 7 passengers
  • Length:32 ft7+1⁄2in (9.94 m)
  • Wingspan:40 ft 8 in (12.40 m)
  • Height:13 ft 0 in (3.96 m)
  • Wing area:229 sq ft (21.3 m2)
  • Airfoil:NACA 634415 at root, 631212
  • Empty weight:3,930 lb (1,783 kg)
  • Max takeoff weight:6,500 lb (2,948 kg)
  • Fuel capacity:190 US gal (160 imp gal; 720 L) total, 187 US gal (156 imp gal; 710 L) useable
  • Powerplant:2 ×Lycoming TIO-540-Aair-cooled six-cylinder horizontally opposedpiston engine,310 hp (230 kW) each
  • Propellers:3-bladed Hartzell metal, fully feathering propellers, 6 ft 8 in (2.03 m) diameter

Performance

  • Maximum speed:261 mph (420 km/h, 227 kn) at 15,000 ft (4,600 m)
  • Cruise speed:238 mph (383 km/h, 207 kn) at 20,000 ft (6,100 m) (econ. cruise)
  • Stall speed:73 mph (117 km/h, 63 kn) (flaps down)
  • Never exceed speed:272 mph (438 km/h, 236 kn)[8]
  • Range:1,165 mi (1,875 km, 1,012 nmi) at 20,000 ft (6,100 m) (econ. cruise speed)
  • Service ceiling:26,300 ft (8,000 m)
  • Rate of climb:1,445 ft/min (7.34 m/s)

See also[edit]

Wikimedia Commons has media related toPiper PA-31.

Related development

Aircraft of comparable role, configuration, and era

References[edit]

Citations[edit]

  1. ^abTaylor 1976, p.354.
  2. ^abcdefghi"The Piper PA-31 Navajo/Pressurized Navajo".airliners.net. 2009. Archived fromthe originalon April 28, 2010.RetrievedJanuary 13,2009.
  3. ^abcdePeperell 1987, pp. 179-201
  4. ^abc"World News: Piper's New Medium Twin".Flight International,Volume 86, Number 2911, 24 December 1964, p.1065. Retrieved 2010-04-05
  5. ^Lambert (1963), p.470
  6. ^ab"Refinements in the Piper range".Flight International,Volume 87, Number 2922, 11 March 1965, p.367. Retrieved 2010-04-05
  7. ^"Air Report",Flight Magazine(1965), p.7
  8. ^abcdefghijkFAA Type Certificate A20SO for Piper PA-31 / PA-31-300 / PA-31-325 / PA-31-350 series aircraftretrieved 2010-04-01
  9. ^abPiper Aircraft Inc. Customer Service Information, p.38
  10. ^ab"Light Commercial & Business: High-flying Navajo".Flight International,Volume 97, Number 3191, p.775. Retrieved 2010-04-08
  11. ^abcdefghijFAA Type Certificate A8EA for Piper PA-31P / PA-31T1 / PA-31T2 / PA-31T3 / PA-31P-350 series aircraftretrieved 2010-04-03
  12. ^"NBA A and after"Flight Internationalmagazine, 14 October 1971, p.603 (online archive version)retrieved 2010-04-05
  13. ^ab"Piper announces Navajo Chieftain"Flight Internationalmagazine, 14 September 1972, p.360 (online archive version)retrieved 2010-04-06
  14. ^abcde"Piper PA-31 Chieftain/Mojave/T-1020/T-1040".airliners.net. Archived fromthe originalon April 28, 2010.RetrievedApril 6,2010.
  15. ^abcManual P/No. 753-703, Introduction, p.3
  16. ^Levy (1983), p.1152
  17. ^abLevy (1983), p.1153
  18. ^abcdBarnett (1983), p.833
  19. ^abcdBarnett, Cliff."Pressurised comfort, piston costs: Mojave flight test",Flight Internationalmagazine, 5 November 1983, p.1232 (online archive version)retrieved 2010-04-05
  20. ^"Argentine Piper factory"Flight Internationalmagazine, 10 May 1973, p.700 (online archive version)retrieved 2010-04-11
  21. ^abAgência Nacional de Aviação Civil Type Certificate EA-7505-02 for EMB 820C Navajo aircraftArchived2010-12-14 at theWayback Machineretrieved 2010-04-11
  22. ^Marsh (2006), p.49
  23. ^Bonelli andPinheiro,(2008), p.34.
  24. ^ab"Caraja deliveries start",Flight Internationalmagazine, 12 January 1985, p.12 (online archive version)retrieved 2010-04-03
  25. ^Manual P/No. 761-775, Introduction, p.3
  26. ^Taylor 1982, pp. 450–451.
  27. ^Taylor 1982, p. 451.
  28. ^Colemill Enterprises."Colemill Pather conversion".Archived fromthe originalon August 15, 2010.RetrievedMay 21,2011.
  29. ^Michell 1994, p. 305.
  30. ^"FAA Supplemental Type Certificate SA970SO"(PDF).faa.gov.RetrievedApril 20,2017.
  31. ^"A total renovation of the PA-31".
  32. ^http:// timetableimages,July 1, 1968 Air West system timetable, page 9
  33. ^https:// timetableimages /i-or/rw7203a.jpg
  34. ^"WCgigantic67".
  35. ^"West Coast Airlines".
  36. ^"WCgigantic67".
  37. ^Hatch, Paul (August 1985). "Air Forces of the World: Chilean Naval Air Service".Air Pictorial.Vol. 47, no. 8. p. 291.
  38. ^ab"World Air Forces 2022".Flightglobal. 2022.RetrievedJuly 18,2022.
  39. ^abHoyleFlight International4–10 December 2018, p. 43.
  40. ^Sixma and LaukkanenAir InternationalJuly 1986, p. 12.
  41. ^"Piper PA31 Navajo".Netmarine.net.RetrievedApril 3,2014.
  42. ^WheelerFlight International4 August 1979, p. 364.
  43. ^ab“Piper Navajo”, information placard, Museo del Aire
  44. ^"Aircraft ZF622 (1980 Piper PA-31-350 Navajo Chieftain C/N 31-8052033) Photo by Malcolm Clarke (Photo ID: AC437577)".airport-data.RetrievedApril 20,2017.
  45. ^"Korean Air Lines McDonnell Douglas DC-10-30, HL7339, SouthCentral Air Piper PA-31-350, N35206, Anchorage, Alaska, December 23, 1983"(PDF).National Transportation Safety Board.August 9, 1984. Archived fromthe original(PDF)on August 25, 2021.RetrievedAugust 29,2021.
  46. ^Chivell, Wayne (July 24, 2003)."Findings of Inquest".airsafety.au.
  47. ^Milovanovic, Selma (January 29, 2003)."Air crash inquest enters final chapter".The Age.
  48. ^Taylor 1976, p.354–355.

Bibliography[edit]

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