40-480: 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. In 1962, Piper began developing a six- to eight-seat twin-engined corporate and commuter transport aircraft under the project name Inca , at
80-410: A free power turbine . The starter has to accelerate only the gas generator, making the engine easy to start, particularly in cold weather. Air enters the gas-generator through an inlet screen into the low-pressure axial compressor . This has three stages on small and medium versions of the engine and four stages on large versions. The air then flows into a single-stage centrifugal compressor , through
120-529: A PT6 and propeller flying test-bed until it was replaced with a Beech King Air in 1980. The King Air test-engine or propeller replaced one of the standard ones. In 1974 the Beech 18 had been unable to fly fast enough and high enough to test the PT6A-50 for the de Havilland Canada Dash 7 so a Vickers Viscount was modified as a PT6 test-bed with a Dash-7 installation in the nose. The first production PT6 model,
160-433: A bleed arrangement which reuses the bleed air by returning it in a tangential direction at the entry to the compressor, an idea patented by Schaum et al. and titled "Turbine Engine With Induced Pre-Swirl at Compressor Inlet". It acts like a variable vane and is known as a "Jet-Flap". All versions of the engine consist of two sections that can be easily separated for maintenance: a gas generator supplies hot pressurized gas to
200-408: A folded annular combustion chamber , and finally through a single-stage turbine that powers the compressors at about 45,000 rpm. Hot gas from the gas generator flows into the power turbine, which turns at about 30,000 rpm. It has one stage on the small engines and two stages on the medium and large ones. For turboprop use, this powers a two-stage planetary output reduction gearbox, which turns
240-624: A gas generator with accessory gearbox, and a free-power turbine with reduction gearbox. In aircraft, the engine is often mounted "backwards," with the intake at the rear and the exhaust at the front, so that the turbine is directly connected to the propeller. Many variants of the PT6 have been produced, not only as turboprops but also as turboshaft engines for helicopters, land vehicles, hovercraft, and boats; as auxiliary power units; and for industrial uses. By November 2015, 51,000 had been produced, which had logged 400 million flight hours from 1963 to 2016. It
280-577: A possible new market such as a Super PC-12, a more powerful TBM, or a bigger King Air. When de Havilland Canada asked for a much larger engine for the DHC-8 , roughly twice the power of the Large PT6, Pratt & Whitney Canada responded with a new design initially known as the PT7, later renamed Pratt & Whitney Canada PW100 . The rate at which parts deteriorate in a gas turbine is unbalanced insofar as
320-532: A proposed 2,000 shp (1,500 kW) engine to replace the most powerful versions of the PT6. It was considered likely to be a development of the PT6C core, and would fit between the 1,750 shp (1,300 kW) PT6C-67C/E and the 2,300 shp (1,700 kW) PW100 family. It was expected to be ready to launch by the end of 2017 for an initial helicopter platform with a 10-15% reduction in brake specific fuel consumption . This 2,000 hp engine would target
360-725: A small gas turbine engine. Demand for the Wasp radial engine was still strong and its production was profitable but the aim was to become Canada's prime engine company by focusing on a small gas turbine engine. Riley gave Guthrie a modest budget of C$ 100,000. Guthrie recruited twelve engineers with experience gained at various places including the National Research Council in Ottawa , Orenda Engines in Ontario , Bristol Aero Engines and Blackburn Aircraft . They completed
400-555: Is a general-purpose light airplane or helicopter , usually used for transporting people, freight, or other supplies, but also used for other duties when more specialized aircraft are not required or available. The term can also refer to an aircraft type certificated under American, Canadian, European, or Australian regulations as a Utility Category Aircraft , which indicates that it is permitted to conduct limited aerobatics . The approved maneuvers include chandelles , lazy eights , spins , and steep turns over 60° of bank. In
440-464: 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
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#1732798166884480-561: Is known for its reliability with an in-flight shutdown rate of 1 per 333,333 hours up to October 2003, 1 per 127,560 hours in 2005 in Canada, 1 per 333,000 hours from 1963 to 2016, 1 per 651,126 hours over 12 months in 2016. Time between overhauls is between 3,600 and 9,000 hours and hot-section inspections between 1,800 and 2,000 hours. Early PT6 versions lacked a FADEC , autothrottle could be installed as an aftermarket upgrade with an actuator , initially for single-engine aircraft like
520-478: Is known for its reliability, with an in-flight shutdown rate of 1 per 651,126 hours in 2016. The PT6A turboprop engine covers the power range between 580 and 1,940 shp (430 and 1,450 kW), while the PT6B/C are turboshaft variants for helicopters. In 1956, Pratt & Whitney Canada's (PWC) president, Ronald Riley, ordered engineering manager Dick Guthrie to hire a team of gas turbine specialists to design
560-578: Is the same as in 1964, updates have included a cooled first-stage turbine vane, additional compressor and turbine stages and single-crystal turbine blades in the early 1990s. Its pressure ratio is 13:1 in the AgustaWestland AW609 tiltrotor, the highest that can be used without cooled turbine blades. In response to the General Electric GE93 , in 2017 Pratt & Whitney Canada started testing core technology and systems for
600-625: The PC-12 and potentially in twin-turboprop aircraft. In October 2019 the PT6 E-Series was launched on the PC-12 NGX, the first general aviation turboprop with an electronic propeller and engine control system with a single lever and better monitoring for longer maintenance intervals, increased from 300 to 600 hours, and a TBO increased by 43% to 5,000 hours, reducing engine operating costs by at least 15%. In April 2022, Daher announced that
640-426: The engine nacelles and a one-piece airstair cabin entry door instead of the split pair of doors. MTOW was increased to 7,800 lb (3,538 kg). 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
680-451: 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. Data from Jane's All The World's Aircraft 1976–77 General characteristics Performance Related development Aircraft of comparable role, configuration, and era Utility aircraft A utility aircraft
720-482: 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 US gal (151 L) auxiliary fuel tanks in each wing. Up to eleven seats could be fitted, and baggage capacity
760-514: The Chieftain tail. 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). The engines variants had intercoolers , and the rear part of the nacelles were baggage lockers. The Mojave's MTOW rose by 200 lb (91 kg) to 7,200 lb (3,266 kg). Certified in 1983, like the T1020 and T1040,
800-748: 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. 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
840-467: The PT6, which first ran in December 1963, was beset with engineering problems, cost overruns and lack of sales. It was almost cancelled. The team lacked the ability to deal with the technical difficulties, i.e. how to develop the engine, because, as one of the team Elvie Smith recalled, they came from research and design backgrounds. They learned how to run a development program, such as testing around
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#1732798166884880-458: The PT6A-20, was the pipe diffuser patented by Vrana, another of the original PT6 team. It replaced the vaned type diffuser used in centrifugal compressors. The pipe diffuser became standard design practice for P&WC. Another design change improved the part-speed functioning of the compressor. It is common to bleed air from a compressor to make it work properly at low engine speeds. The PT6 has
920-683: The PT6A-6, was certificated in December 1963. The first application was the Beech Queen Air , enticing the U.S. Army to buy a fleet of the U-21 Ute variant. This helped launch the King Air with Beechcraft selling about 7,000 by 2012. From 1963 to 2016 power-to-weight ratio was improved by 50%, brake specific fuel consumption by 20% and overall pressure ratio reached 14:1. Its development continues and while today its basic configuration
960-651: The United States, military utility aircraft are given the prefix U in their designations . This aircraft-related article is a stub . You can help Misplaced Pages by expanding it . Pratt %26 Whitney Canada PT6 The Pratt & Whitney Canada PT6 is a turboprop aircraft engine produced by Pratt & Whitney Canada . Its design was started in 1958, it first ran in February 1960, first flew on 30 May 1961, entered service in 1964, and has been continuously updated since. The PT6 consists of two basic sections:
1000-460: The clock rather than on one shift, from a PWA team which directed the development for several months. The PT6 first flew on 30 May 1961, mounted as a third engine in the nose of a Beech 18 aircraft which had been converted by de Havilland at its Downsview facility in North York, Ontario . Full-scale production started in 1963, with service entry the following year. The Beech 18 continued as
1040-714: The compressor intake by inertial separators in the inlet. In some installation such as the PT6A-66B version in the Piaggio P.180 Avanti , the engine is reversed, with the propeller acting as a "pusher", the accessory gearbox facing the front of the aircraft. By the 40th anniversary of its maiden flight in 2001, over 36,000 PT6As had been delivered, not including the other versions. Up to October 2003, 31,606 delivered engines have flown more than 252 million hours. Till November 2015, 51,000 have been produced. The family logged 400 million flight hours from 1963 to 2016. The PT6 family
1080-515: The detailed design of an engine for Canadair's small jet trainer, the CL-41 . It was a 3,000-pound-force (13 kN) thrust turbojet but the design was taken over by P&WA who developed it into the Pratt & Whitney JT12 . The team had to wait for market assessments to define their next engine, a 450 shaft horsepower (340 kW) turboprop for twin-engined aircraft, the PT6. The early development of
1120-656: 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 6,200 to 6,500 lb (2,812 to 2,948 kg), 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 (224 kW) Lycoming IO-540-M1A5 engines driving two-bladed propellers. Unofficially,
1160-421: The hottest parts need replacing or repairing more often than the cooler-running parts. If the hotter parts can be removed without disturbing the rest of the engine, for example without removing the complete engine from the aircraft, maintenance costs are reduced. It was achieved with the PT6 by having the hottest parts, the gas generator turbine and combustor, at the propeller end. They are removed without disturbing
1200-621: 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 (317 kW) Lycoming TIGO-541-E engines, had a longer nose, fewer and smaller windows, 25 US gal (95 L) fuel tanks in
1240-506: The pilot to enter the cockpit. 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 and counter-rotating propellers to prevent critical engine handling problems. 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
Piper PA-31 Navajo - Misplaced Pages Continue
1280-464: The power section at the front of the nacelle, where it can drive the propeller directly without the need for a long shaft. Intake air is usually fed to the engine via an underside mounted duct, and the two exhaust outlets are directed rearward. This arrangement aids maintenance by allowing the entire power section to be removed along with the propeller, exposing the gas-generator section. To facilitate rough-field operations, foreign objects are diverted from
1320-428: The propeller at a speed of 1,900 to 2,200 rpm. The exhaust gas then escapes through two side-mounted ducts in the power turbine housing. The turbines are concentric with the combustion chamber, reducing overall length. In most aircraft installations the PT6 is mounted so that the intake end of the engine is towards the rear of the aircraft, leading to it being known by many as the "back-to-front" engine. This places
1360-722: 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 (231 kW) 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
1400-476: The rest of the engine with its connections to the aircraft. This arrangement was patented by designer Newland, one of the original PT6 team. A similar general arrangement with a free-turbine power take-off at the exhaust end (the 1,000 shp (750 kW) P.181 engine) had been shown by Armstrong Siddeley Motors at the Farnborough Airshow in 1957. An early design improvement, incorporated in
1440-587: The updated SOCATA TBM -960 would be powered by the PT6E-66XT. The main variant, the PT6A , is available in a wide variety of models, covering the power range between 580 and 920 shaft horsepower (430 and 690 kilowatts ) in the original series, and up to 1,940 shaft horsepower (1,450 kilowatts) in the 'large' lines. The PT6B and PT6C are turboshaft variants for helicopters. In US military use, they are designated as T74 or T101 . Several other versions of
1480-578: 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. The Navajo family is popular with air charter companies, small feeder airlines and commuter air carriers in many countries, and
1520-521: 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 6 in (3.51 m) 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
1560-517: Was increased to 7,000 lb (3,175 kg). 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 (242 kW), lower rated versions of the Chieftain's counter-rotating engines. It was certified in May 1974, and production commenced in
1600-555: Was reduced from 700 to 600 lb (318 to 272 kg) 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
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