Pratt & Whitney Canada PT6

{{short description|Turboprop aircraft engine family by Pratt & Whitney Canada}} {{redirect|PT6||PT6 (disambiguation)}} {{Use dmy dates|date=April 2020}}  {{infobox aero engine | name = PT6 | image = P&W PT6 (cropped).jpg | caption = A PT6A-20 on display at the Canada Aviation and Space Museum |engine_type= Turboprop / turboshaft |national_origin = Canada |manufacturer= Pratt & Whitney Canada |first_run= 1960<ref name=pt6nation_1>{{cite web|url=http://www.pt6nation.com/en/the-legend|title=PT6 engine - The Legend|website=PT6 Nation|publisher= Pratt & Whitney Canada|archive-url=https://web.archive.org/web/20130219035548/http://www.pt6nation.com/en/the-legend|archive-date=2013-02-19}}</ref> |major_applications= AgustaWestland AW139  Beech King Air  and Super King Air  Beech Starship  Baykar Bayraktar Akıncı Cessna 208 Caravan  de Havilland Canada DHC-6 Twin Otter  Pilatus PC-12  Piper M700 Fury  |number_built = 64,000 (as of February 2023)<ref name="RE151116">{{cite web |url= https://verticalmag.com/press-releases/pratt-whitney-canada-celebrates-1b-flying-hours-and-60-years-of-pt6-innovation|title= Pratt & Whitney Canada celebrates 1 billion flying hours and 60 years of PT6 innovation}}</ref> |developed_from = |developed_into = |variants_with_their_own_articles = Pratt & Whitney Canada PT6T }}

The '''Pratt & Whitney Canada PT6''' is a family of turboprop aircraft engines produced by Pratt & Whitney Canada.  It was designed in 1958, first flew on 30 May 1961, entered service in 1964, and has been continually updated since.  The PT6 consists of two basic sections: 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 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 {{cvt|580|and|1940|shp}}, while the '''PT6B/C''' are turboshaft variants for helicopters.

== Development==

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 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.<ref>Power - The Pratt & Whitney Canada Story, Kenneth H. Sullivan & Larry Milberry, CANAV Books 1989, {{ISBN|0-921022-01-8}}, p. 116</ref> They completed the detailed design of an engine for Canadair's small jet trainer, the CL-41. It was a {{convert|3000|lbf|kN|adj=on}} thrust turbojet but the design was taken over by the US headquarters, who developed it into the Pratt & Whitney JT12. The team had to wait for market assessments to define their next engine, a {{convert|450|shp|kW}} turboprop for twin-engined aircraft, the PT6.<ref name="flightglobal.com">https://www.flightglobal.com/pdfarchive/view/1990/1990%20-%200238.html?search=pt6%20phenomenon {{Dead link|date=February 2022}}</ref> The early development of the PT6, which first flew in May-June 1961,<ref name=pt6nation_1/><ref>{{cite journal|title=Pratt's 'dirty dozen'|journal=Aviation Week and Space Technology|pages=42–43}}</ref> was beset with engineering problems, cost overruns and lack of sales. It was almost cancelled.<ref name="flightglobal.com"/> 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 the clock rather than on one shift, from a PWA team which directed the development for several months.<ref>Power - The Pratt & Whitney Canada Story, Kenneth H. Sullivan & Larry Milberry, CANAV Books 1989, {{ISBN|0-921022-01-8}}, p. 132</ref>

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 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.<ref>Power - The Pratt & Whitney Canada Story, Kenneth H. Sullivan & Larry Milberry, CANAV Books 1989, {{ISBN|0-921022-01-8}}, p. 290</ref>

The first production PT6 model, 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.<ref>{{cite news |url= http://aviationweek.com/blog/little-engine-could-and-did |title= The Little Engine That Could ... and Did |date= 30 October 2012 |department= Business Aviation Now |work= Aviation Week Network }}{{Dead link|date=December 2024 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> 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.<ref name=AirInsightJune2016>{{cite news |url= http://airinsight.com/2016/06/09/discussion-pratt-whitney-canada-president-john-saabas/ |title= A Discussion with Pratt & Whitney Canada President John Saabas |publisher= AirInsight |date= 9 June 2016 |access-date= 9 June 2016 |archive-date= 17 August 2016 |archive-url= https://web.archive.org/web/20160817084047/http://airinsight.com/2016/06/09/discussion-pratt-whitney-canada-president-john-saabas/ |url-status= dead }}</ref> Its development continues and while today its basic configuration 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.<ref>{{cite news |url= https://www.flightglobal.com/news/articles/analysis-ge-aviation-unveils-strategy-for-dethronin-427543/ |title= GE Aviation unveils strategy for dethroning PT6 |work= Flight Global |date= 25 July 2016}}</ref>

In response to the General Electric GE93, in 2017 Pratt & Whitney Canada started testing core technology and systems for a proposed {{cvt|2000|shp|kW}} engine to replace the most powerful versions of the PT6.<ref>{{cite news |url= https://www.flightglobal.com/news/articles/ebace-core-technology-tests-set-to-begin-for-pt6-re-437436/ |title= Core technology tests set to begin for PT6 replacement |date= 22 May 2017 |work= Flight Global |author= Stephen Trimble}}</ref> It was considered likely to be a development of the PT6C core, and would fit between the {{cvt|1750|shp|kW}} PT6C-67C/E and the {{cvt|2300|shp|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.<ref>{{cite news |url= http://aviationweek.com/ebace-2017/pt6-engine-change |title= PT6 – Engine of Change? |date= 23 May 2017 |author= Paul Jackson |work= ShowNews |publisher= Aviation Week Network}}</ref> This 2,000 hp engine would target a possible new market such as a Super PC-12, a more powerful TBM, or a bigger King Air.<ref>{{cite news |url= http://aviationweek.com/nbaa-2017/pwc-opens-new-pt6-growth-engine |title= PWC Opens Up on New PT6 Growth Engine |date= 12 October 2017 |author= Guy Norris |work= Aviation Week & Space Technology}}</ref>

=== PW100 === 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.

==Design== [[File:Reduction Gear.jpg|thumb|Epicyclic reduction gears on Pratt & Whitney Canada PT6 gas turbine engine]]

The rate at which parts deteriorate in a gas turbine is unbalanced insofar as 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 the rest of the engine with its connections to the aircraft. This arrangement was patented by designer Newland, one of the original PT6 team.<ref>{{Cite web|url=https://patents.google.com/patent/US3152443A/en|title=Gas turbine powerplant}}</ref> A similar general arrangement with a free-turbine power take-off at the exhaust end (the {{cvt|1000|shp|kW}} P.181 engine) had been shown by Armstrong Siddeley Motors at the Farnborough Airshow in 1957.<ref>https://www.flightglobal.com/pdfarchive/view/1958/1958%20-%200224.html?search=february%20armstrong%20siddeley%20motors {{Dead link|date=February 2022}}</ref>

An early design improvement, incorporated in the PT6A-20,<ref>https://www.flightglobal.com/FlightPDFArchive/1990/1990%20-%200242.PDF {{Dead link|date=February 2022}}</ref> was the pipe diffuser patented by Vrana, another of the original PT6 team.<ref>{{Cite web|url=https://patents.google.com/patent/US3333762A/en|title=Diffuser for centrifugal compressor}}</ref> It replaced the vaned type diffuser used in centrifugal compressors. The pipe diffuser became standard design practice for P&WC.<ref>{{Cite book|chapter-url=https://asmedigitalcollection.asme.org/GT/proceedings/GT1993/78880/V001T01A002/243489|chapter=The PT6 Engine: 30 Years of Gas Turbine Technology Evolution|first1=M.|last1=Badger|first2=A.|last2=Julien|first3=A. D.|last3=LeBlanc|first4=S. H.|last4=Moustapha|first5=A.|last5=Prabhu|first6=A. A.|last6=Smailys|title=Volume 1: Aircraft Engine; Marine; Turbomachinery; Microturbines and Small Turbomachinery|date=25 February 2015|publisher=American Society of Mechanical Engineers Digital Collection|via=asmedigitalcollection.asme.org|doi=10.1115/93-GT-006|isbn=978-0-7918-7888-0}}</ref> 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 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".<ref>{{Cite web|url=https://patents.google.com/patent/US4222703A/en|title=Turbine engine with induced pre-swirl at compressor inlet}}</ref> 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 a free power turbine.<ref name=pt6nation_2>{{cite web|url=http://www.pt6nation.com/en/articles/article/history-an-engine-ahead-of-its-time/|title=An Engine Ahead of Its Time|author=|website=PT6 Nation|publisher=Pratt & Whitney Canada|access-date=30 July 2014|archive-date=7 June 2013|archive-url=https://web.archive.org/web/20130607032911/http://www.pt6nation.com/en/articles/article/history-an-engine-ahead-of-its-time/|url-status=dead}}</ref> The starter has to accelerate only the gas generator, making the engine easy to start, particularly in cold weather.<ref name=pt6nation_2 /> 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 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 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.<ref name="flightglobal.com"/> This places 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 the compressor intake by inertial separators in the inlet.<ref>{{cite journal| journal=AOPA Pilot| title=The PT6 at 50 | author=Thomas A. Horne| page=T-7| date=December 2013 | url = https://www.aopa.org/news-and-media/all-news/2013/december/pilot/milestones-the-pt6-at-50 }}</ref> 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.

thumb|upright=3|center|From left to right: propeller mount, reduction gear, exhaust, 2-stage free power turbine, 1-stage gas generator turbine surrounded by the combustor, 1 centrifugal then 4 axial compressor stages, intake, and accessories

==Operational history==

By the 40th anniversary of its maiden flight in 2001, over 36,000 PT6As had been delivered, not including the other versions.<ref>{{cite press release |url= http://www.pwc.ca/en/news-events/press/details/367475 |title= Pratt & Whitney Canada's PT6 Turboprop Marks 40 Years of In-flight Success |date= 18 June 2001 |publisher= Pratt & Whitney Canada |url-status= dead |archive-url= https://web.archive.org/web/20131005001225/http://www.pwc.ca/en/news-events/press/details/367475 |archive-date= 5 October 2013 |df= dmy-all }}</ref> Up to October 2003, 31,606 delivered engines have flown more than 252 million hours.<ref name=Flight21sep2004>{{cite web |url= https://www.flightglobal.com/news/articles/flight-test-pilatus-pc-12-power-of-one-187732/ |title= FLIGHT TEST: Pilatus PC-12 - Power of one |publisher= flightglobal |date= 21 September 2004}}</ref> Till November 2015, 51,000 have been produced.<ref name="RE151116"/> The family logged 400 million flight hours from 1963 to 2016.<ref name=AirInsightJune2016/>

The PT6 family is known for its reliability with an in-flight shutdown rate of 1 per 333,333 hours up to October 2003,<ref name=Flight21sep2004/> 1 per 127,560 hours in 2005 in Canada,<ref>{{cite web |date= 16 January 2012 |title= Evaluation-Single-Engine Turbine Airplanes Transporting Passengers in IFR Flight or Night VFR |publisher= Transport Canada |url= https://www.tc.gc.ca/eng/civilaviation/publications/tp185-3-07-feature-3772.htm}}</ref> 1 per 333,000 hours from 1963 to 2016,<ref name=AirInsightJune2016/> 1 per 651,126 hours over 12 months in 2016.<ref>{{cite news |url= https://www.flightglobal.com/news/articles/flight-test-upgraded-pilatus-pc-12-powers-ahead-426092/ |title= Flight test: Upgraded Pilatus PC-12 powers ahead |publisher= flightglobal |date= 6 June 2016 |author= Mike Gerzanics}}</ref> Time between overhauls is between 3,600 and 9,000 hours and hot-section inspections between 1,800 and 2,000 hours.<ref>{{cite web |url= http://www.pt6nation.com/en/community/story/the-most-bang-for-the-bucks-pa/ |title= PT6A engine TBO and HSI scheduling |publisher= Pratt & Whitney Canada |access-date= 2 March 2016 |archive-date= 7 March 2016 |archive-url= https://web.archive.org/web/20160307011326/http://www.pt6nation.com/en/community/story/the-most-bang-for-the-bucks-pa/ |url-status= dead }}</ref>

Early PT6 versions lacked a FADEC, autothrottle could be installed as an aftermarket upgrade with an actuator, initially for single-engine aircraft like the PC-12 and potentially in twin-turboprop aircraft.<ref>{{cite news |url= http://aviationweek.com/technology/autothrottle-feature-provides-hands-free-turboprop-power |title= Autothrottle Feature Provides Hands-Free Turboprop Power |date= 12 July 2017 |author= John Croft |work= Aviation Week & Space Technology}}</ref> 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%.<ref>{{cite press release |url= https://www.pwc.ca/en/company/news-and-events/news-details/pratt-whitney-launches-the-first-dual-channel?id=123318 |title= Pratt & Whitney Launches the First Dual-Channel Integrated Electronic Propeller and Engine Control System in the General Aviation Turboprop Market |date= Oct 21, 2019 |publisher= Pratt & Whitney}}</ref> In April 2022, Daher announced that the updated SOCATA TBM-960 would be powered by the PT6E-66XT.<ref>{{cite press release |url= https://www.daher.com/en/daher-launches-the-tbm-960-very-fast-turboprop-aircraft-with-digital-power/ |title= Daher launches the TBM 960 very fast turboprop aircraft with digital power |date= April 5, 2022 |publisher= Daher}}</ref>

==Variants== thumb|A PT6A-67D engine on a Beechcraft 1900D. The turbine exhaust (copper-colored pipe) is prominent.|alt= The main variant, the '''PT6A''', is available in a wide variety of models, covering the power range between {{convert|580|and|920|shp|kW|abbr=off|lk=on}} in the original series, and up to {{convert|1940|shp|kW|abbr=off}} 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 the PT6 have appeared over time: *the '''Large PT6''' added an extra axial compressor stage(4), and another power turbine stage(2) and a deeper output reduction, producing almost twice the power output, between {{convert|1090|and|1920|shp|abbr=off}}. *the Medium '''PT6''' added another power turbine stage(2) -41 thru the -60 engines <ref>{{Cite web |title=IASCANADA.COM |url=http://www.iascanada.com/engmodels.html |access-date=2024-12-10 |website=www.iascanada.com}}</ref> *the '''PT6B''' is a helicopter turboshaft model, featuring an offset reduction gearbox with a freewheeling clutch and power turbine governor, producing {{convert|1000|hp|abbr=off}} at 4,500 rpm. *the '''PT6C''' is a helicopter model, with a single side-mounted exhaust, producing {{convert|2000|hp|abbr=off}} at 30,000 rpm, which is stepped down in a user-supplied gearbox. *the '''PT6E''' is a large PT6A derivative equipped with digital engine control. *the '''PT6T Twin-Pac''' consists of two PT6 engines driving a common-output reduction gearbox, producing almost {{convert|2000|hp|abbr=off}} at 6,000 rpm. *the '''ST6''' is a version intended for stationary applications, originally developed for the UAC TurboTrain, and now widely used as auxiliary power units on large aircraft, as well as many other roles.<ref>{{Cite web|url=http://www.turbokart.com/about_pt6.htm|title=Pratt & Whitney PT6A-42 Turboprop|website=Turbokart.com|access-date=9 February 2007|archive-date=22 October 2017|archive-url=https://web.archive.org/web/20171022222702/http://www.turbokart.com/about_pt6.htm|url-status=dead}}</ref>

The '''PT6A''' family is a series of free-turbine turboprop engines providing {{convert|500|to|1940|shp|kW|abbr=off}}

===Small=== {|class="wikitable sortable" style=v-align:top |+Small<ref name="PTTC">{{Cite web|url=http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/0/90c641493420043b8625752f006482e8/$FILE/E4EA_rev24.pdf|title=Pratt & Whitney Canada PT6 Series Type Certificate|website=RGL.FAA.gov|date=2007-06-21|publisher=Federal Aviation Administration|access-date=28 November 2009|archive-date=10 September 2010|archive-url=https://web.archive.org/web/20100910145359/http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/0/90c641493420043b8625752f006482e8/$FILE/E4EA_rev24.pdf|url-status=dead}}</ref> !variant!!equivalent shaft horsepower (eshp)!!shaft horsepower (shp)!!applications<ref name="pwc.ca/en/engines/pt6a">{{Cite web|url=http://www.pwc.ca/en/engines/pt6a|title=PT6A|website=PWC.ca|publisher=Pratt & Whitney Canada}}</ref> |- |'''PT6A-6, 6A, 6B'''||525||500||Heron-TP-XP UAV from Israel<ref>{{Cite web|title=Home {{!}} SIPRI|url=https://www.sipri.org/|access-date=2022-03-14|website=www.sipri.org}}</ref> |- |'''PT6A-11'''||528||500|| |- |'''PT6A-11AG'''||580||550||Air Tractor AT-400 (402A / 402B) Schweizer Ag-Cat G-164B Turbine |- |'''PT6A-15{{Abbr|AG|agricultural}}'''||715||680||Air Tractor AT-400 (402A/402B) Air Tractor AT-502, -502A and -502B Frakes Turbocat Model A / B / C Schweizer Ag-Cat G-164B Turbine |- |'''PT6A-20'''||579||550||De Havilland Canada DHC-6 Twin Otter Srs. 100–200 |- |'''PT6A-20A, -20B, -6/C20'''||579||550|| |- |'''PT6A-21'''||580||550||Beechcraft King Air C90A / B / SE Beechcraft Bonanza (turbine conversion) Royal Turbine Duke Evektor EV-55 Outback JetPROP DL |- |'''PT6A-25, -25A'''||580||550||Beechcraft T-34C Turbo Mentor Pilatus PC-7 Turbo Trainer |- |'''PT6A-25C'''||783||750||Embraer EMB 312 Tucano Pilatus PC-7 Mk.II M PZL-130 Orlik / TC-II Turbo-Orlik |- |'''PT6A-27'''||715||680||Beechcraft Model 99A, B99 De Havilland Canada DHC-6 Twin Otter 300 Harbin Y-12 (CATIC / HAIG) Embraer EMB 110 Bandeirante Let L-410 Turbolet Pilatus PC-6/B Turbo-Porter |- |'''PT6A-28'''||715||680||Embraer EMB 121 Xingu Beechcraft King Air 100 Series |- |'''PT6A-29'''||778||750|| |- |'''PT6A-34'''||783||750||Embraer EMB 110 Bandeirante/111 Embraer EMB 821 Carajá Grumman Mallard (Frakes turbine conversion) JetPROP DLX PAC P-750 XSTOL (750XL) Quest Kodiak (Daher) Vazar Dash 3 Turbine Otter De Havilland Canada DHC-6 Twin Otter 400 Thrush S2R-T34 Pilatus PC-6/B Turbo-Porter (STC) BX Turbo de Havilland Canada Beaver DHC-2 (STC) ARON M80 |- |'''PT6A-34B'''||783||750|| |- |'''PT6A-34AG'''||783||750||Air Tractor AT-502B Frakes/Grumman Turbo-Cat Model A / B / C Pacific Aerospace 750 PZL-Okecie PZL-106 Turbo Kruk Schweizer Ag-Cat G-164B/D Turbine Thrush Model 510P Thrush S2R-T34 |- |'''PT6A-35'''||787||750||Blue 35 JetPROP DLX |- |'''PT6A-36'''||783||750||Thrush S2R-T34 (dry configuration only) |- |'''PT6A-38'''||801||750|| |- |'''PT6A-110'''||502||475||Schweizer AG-Cat Turbine Royal Turbine Duke |- |'''PT6A-112'''||528||500||Cessna Conquest I |- |'''PT6A-114'''||632||600||Cessna 208 Caravan |- |'''PT6A-114A'''||725||675||Cessna 208 Caravan 675, 208B |- |'''PT6A-116'''||736||700|| |- |'''PT6A-121'''||647||615|| |- |'''PT6A-135'''||787||750||EMB 121A1 Xingu II |- |'''PT6A-135A'''||787||750||Beechcraft King Air F90-1 / C90GT / C90GTi / C90GTx Blackhawk XP135A Cheyenne Series Blackhawk XP135A Conquest I Blackhawk XP135A King Air 90 Series Cessna Conquest I JMB Evolution (formerly Lancair Evolution) Silverhawk 135 / StandardAero C90 / E90 StandardAero Cheyenne Series StandardAero King Air F90 T-G Aviation Super Cheyenne Vazar Dash 3 Turbine Otter |- |'''PT6A-140'''||912||867||Cessna Grand Caravan EX |- |'''PT6A-140A'''||945||900||ASIC ULtimate Grand Caravan (upgrade) Blackhawk Aerospace XP140 (Caravan upgrade) Evolution Aircraft EVOT-850 (formerly Lancair) SuperPac 750XL-II (upgrade to the PAC P-750 XSTOL ) |- |'''PT6A-140AG'''||911||867||Air Tractor 502XP Thrush Model 510P2+ |}

===Medium=== {|class="wikitable sortable" |+Medium<ref name=PTTC/> !variant!!equivalent shaft horsepower (eshp)!!shaft horsepower (shp)!!applications<ref name="pwc.ca/en/engines/pt6a"/> |- |'''PT6A-40'''||749||700|| |- |'''PT6A-41, -41AG'''||903||850||Beechcraft King Air 200 / B200 Piper Cheyenne III / IIIA Beechcraft C-12 Huron Thrush S2R-T34 (-41 and -41AG) |- |'''PT6A-42, -42A'''||903||850||Beechcraft C-12 Huron E and F Beechcraft King Air 200 / B200 Blackhawk XP42 King Air 200 StandardAero King Air 200 Blackhawk XP42A C-208 Caravan Series (-42A) Piper Meridian (-42A) Thrush S2R-T34 Indonesian Aerospace N-219 |- |'''PT6A-45'''||1070||1020|| |- |'''PT6A-45R, -45A, -45B'''|| || || |- |'''PT6A-50'''||1022||973||de Havilland Canada DHC-7 Dash 7 |- |'''PT6A-52'''||898||850||Beechcraft King Air B200GT / 250 Blackhawk XP52 King Air 200 / B200 Enhanced Aero B200GTO StandardAero King Air 200 / B200 Piper PA-46 (M700 Fury) |- |'''PT6A-60, -60A'''||1113||1050||Beechcraft Super King Air 300 / 350 |- |'''PT6A-60AG'''||1081||1020||Air Tractor AT-602 Ayres Thrush 550P Ayres Thrush 660 |- |'''PT6A-61'''||902||850||Short C-23 Sherpa |- |'''PT6A-62'''||1008||950<ref>{{Cite web|url=https://easa.europa.eu/system/files/dfu/EASA-TCDS-E.078_(IM)_Pratt_and_Whitney_Canada_PT6A--41_series_engines-01-31082007.pdf|title=Pratt and Whitney Canada PT6A-41 series engines Type Certificate|publisher=EASA|date=31 August 2007|access-date=10 March 2016|archive-date=19 December 2017|archive-url=https://web.archive.org/web/20171219005848/http://www.easa.europa.eu/system/files/dfu/EASA-TCDS-E.078_%28IM%29_Pratt_and_Whitney_Canada_PT6A--41_series_engines-01-31082007.pdf|url-status=dead}}</ref>||KAI KT-1 / KO-1 Pilatus PC-9 Turbo Trainer |}

===Large=== {|class="wikitable sortable" |+Large<ref name=PTTC2>{{Cite web|url=http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/0/e75fff3c2778293786257547006e5c24/$FILE/E26NE.pdf|title=PT6A -64/-66/-67/-68 Series Type Certificate|website=RGL.FAA.gov|publisher=Federal Aviation Administration|access-date=2009-11-28}}{{Dead link|date=May 2025 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> !variant!!equivalent shaft horsepower (eshp)!!shaft horsepower (shp)!!applications<ref name="pwc.ca/en/engines/pt6a"/> |- |'''PT6A-64'''||747||700||EADS Socata TBM 700 |- |'''PT6A-65B, -65R'''<ref name=PTTC/>||1249||1173||Beechcraft 1900 / 1900C Polish Aviation Factory M28 Skytruck |- |'''PT6A-65AG, -65AR'''<ref name=PTTC/>||1298||1220||Air Tractor AT-602 Air Tractor AT-802 / 802A / 802AF / 802F Ayres Thrush 660 / 710P AMI DC-3 (-65R) Dodson International Turbo Dakota DC-3 Shorts 360 Advanced (-65AR) |- |'''PT6A-65SC'''|| ||1100||Cessna 408 SkyCourier LUS-222 |- |'''PT6A-66, -66A, -66D'''||905||850||National Aerospace Laboratories SARAS Piaggio P.180 Avanti Ibis Ae270 HP (-66A) Daher TBM 850, 900, 910, 930 and 940 (formerly EADS Socata TBM) (-66D) |- |'''PT6A-66B, -66T'''||1010||950||Piaggio P180 Avanti II (-66B) |- |'''PT6A-67, -67A, -67B'''||1273||1200||Beechcraft RC-12 Guardrail (-67) Beechcraft Starship (-67A) Epic LT (-67A) Epic E1000<ref>https://epicaircraft.com/specifications/</ref> (-67A) IAI Heron TP (-67A) |- |'''PT6A-67B, -67P PT6E-67XP'''||1272||1200||Pilatus PC-12 (-67B) Pilatus PC-12NG (-67P) Pilatus PC-12NGX (PT6E-67XP) |- |'''PT6A-67D'''||1285||1214||Beechcraft 1900D |- |'''PT6A-67AF, -67AG, -67R, -67T, -67RM'''||1294||1220||Air Tractor AT-802 / 802A / 802AF / 802F (-67AG) Ayres Thrush 710P (-67AG) Basler Turbo BT-67 (-67R) Shorts 360 / 360–300 (-67R) |- |'''PT6A-67E'''||1276||1200|| |- |'''PT6A-67F'''||1796||1700||Air Tractor AT-802 / 802A / 802AF / 802F |- |'''PT6A-68'''||1324||1250||T-6A Texan II |- |'''PT6A-68B, -68C, -68T, -68D'''||1691||1600||Pilatus PC-21 (-68B) Embraer EMB-314 Super Tucano (-68C) TAI Hürkuş (-68T) |}

;T74-CP-700 :(PT6A-20) United States military designation for the PT6A-20/27, used in the Beechcraft U-21 Ute. ;T74-CP-702 :(PT6A-29) ;T101 :United States military designation for the T101-CP-100 / PT6A-45R, used in the Shorts 330 and Shorts C-23 Sherpa. ;PT6B-9 :The '''PT6B-9''' is a {{convert|550|hp|kW|abbr=off|1}} turboshaft engine for use in helicopters; a later mark of PT6B is rated at {{convert|981|hp|kW|abbr=off|1}}. ;PT6B-16: ;PT6C :The PT6C is a {{convert|1600|to|2300|shp|kW|abbr=off}} engine for helicopters and tiltrotors. ;PT6D-114A :The PT6D-114A is based on the PT6A-114A; the main difference is the deletion of the second-stage reduction gearing and output shaft, because the engine is intended for integration with a combining gearbox incorporating power turbine governors and a propeller output shaft.<ref>{{Cite web|url=http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/0/90C641493420043B8625752F006482E8?OpenDocument|title=PT6 Type Certificate Data Sheet Information|website=RGL.FAA.gov|publisher=Federal Aviation Administration}}</ref> ;Soloy Dual Pac:2x PT6D-114A engines driving a single propeller through a combining gearbox, capable of independent operation. ;PT6T :Twin PT6 power units combining outputs through a gearbox for use in helicopters. ;ST6 :The '''ST6''' is a variant of the PT6 that was originally developed as a powerplant for the UAC TurboTrain power cars, but later developed as a stationary power generator and auxiliary power unit. ;ST6B :The ST6B-62 was a {{convert|550|bhp|abbr=off}} version of the PT6 developed for use in the STP-Paxton Turbocar, raced in the 1967 Indianapolis 500.<ref name="Magazines1967">{{Cite journal|author=Bill Kilpatrick|title=The Big Engine That Almost Did|journal=Popular Mechanics|url=https://books.google.com/books?id=rtMDAAAAMBAJ&pg=PA69|date=August 1967|publisher=Hearst Magazines|pages=69–71|access-date=2011-06-26|issn=0032-4558}}</ref> ;STN 6/76 :The STN 6/76 was a {{convert|500|bhp|abbr=off}} version of the PT6 developed for use in the Lotus 56, raced in the 1968 Indianapolis 500 and later in Formula One races, in 1971.<ref>{{Cite web|url=http://www.research-racing.de/Lotus56B-1.htm|title=Lotus, Pratt & Whitney 56B|publisher=Grand Prix Racing Online|website=Research Racing}}</ref><ref>{{Cite web|url=http://www.f1technical.net/f1db/cars/271|title=Lotus 56B Pratt & Whitney|website=F1Technical.net|publisher=F1 Technical}}</ref>

==Applications== The engine is used in over 100 different applications.

===PT6B=== * AgustaWestland AW119 Koala * Avicopter AC313 * Changhe Z-8F * Lockheed XH-51 * Sikorsky S-76B * Westland Lynx 606

===PT6C=== * Airbus Helicopters H175/Avicopter Z-15 * AgustaWestland AW139 * AgustaWestland AW609 * Bell UH-1 Global Eagle upgrade

===PT6D=== * Soloy Pathfinder 21

===PT6E=== * Pilatus PC-12NGX

===ST6=== * Lockheed L1011 TriStar (as an APU)<ref>{{Cite web |title=ST6L-73 Tristar Auxiliary Power Unit |url=https://gasturbineworld.co.uk/tristar-aircraft-apu/ |access-date=2025-01-31 |website=gas turbine world |language=en-US}}</ref> * STP-Paxton Turbocar Indy racer * UAC TurboTrain

===STN=== * Lotus 56 USAC and Formula 1 racing car

==Engines on display==

* New England Air Museum, Connecticut (cutaway)<ref>{{cite web|url=http://www.neam.org/index.php?option=com_content&view=article&layout=edit&id=1121|title=Pratt & Whitney Canada PT6 Cutaway|website=New England Air Museum}}</ref>

==Specifications (PT6A-6)== {{jetspecs   |ref=Jane's 62-63,<ref name=JAWA62-63>{{cite book|last=Taylor|first=John W.R. FRHistS. ARAeS|title=Jane's All the World's Aircraft 1962-63|year=1962|publisher=Sampson, Low, Marston & Co Ltd|location=London}}</ref> |type=Turboprop |length={{convert|62|in|mm|abbr=on|0}} |diameter={{convert|19|in|mm|abbr=on|0}} |weight={{convert|270|lb|kg|abbr=on|2}} |compressor=3-stage axial + 1-stage centrifugal flow compressor |combustion=annular reverse-flow with 14 Simplex burners |turbine=1-stage gas generator power turbine + 1-stage free power turbine |fueltype=Aviation kerosene to MIL-F-5624E / JP-4 / JP-5 |oilsystem=Split system with gear type pressure and scavenge pumps, with pressure to gearbox boosted by a second pump. |power={{convert|578|hp|kW|abbr=on|0}} equivalent power at 2,200 output rpm for take-off |thrust= |compression=6.3:1 |bypass= |aircon={{convert|5.3|lb/s|kg/s|abbr=on|0}} |turbinetemp= |fuelcon= |specfuelcon=0.67 lb/hph (0.408 kg/kWh) |power/weight=2.14 hp/lb (3.52 kW/kg) |thrust/weight= }}

==Gas Turbine Engines== {| class="wikitable sortable" |+Gas Turbine Engines<ref>{{cite news |url= http://www.geocities.jp/nomonomo2007/AircraftDatabase/AWdata/AviationWeekPages/GTEnginesAWJan2008.pdf |title= Gas Turbine Engines |date= 28 January 2008 |work= Aviation Week |pages= 137–138 |access-date= 26 July 2018 |archive-url= https://web.archive.org/web/20181106021310/http://www.geocities.jp/nomonomo2007/AircraftDatabase/AWdata/AviationWeekPages/GTEnginesAWJan2008.pdf |archive-date= 6 November 2018 |url-status= dead }}</ref> ! rowspan=2 scope="col" style="width: 10%;" | model ! rowspan=2 scope="col" style="width: 10%;" | stages{{efn|axial, centrifugal compressor / HP, LP turbine}} ! colspan=2 scope="col" style="width: 10%;" | power ! colspan=2 scope="col" style="width: 10%;" | SFC /h ! rowspan=2 scope="col" style="width: 5%;" | OPR ! rowspan=2 scope="col" style="width: 5%;" | dia. ! rowspan=2 scope="col" style="width: 5%;" | leng. ! colspan=2 scope="col" style="width: 10%;" | weight ! rowspan=2 scope="col" style="width: 35%;" | applications |- ! hp !! kW !! lb/hp !! g/kW !! lb !! kg |- | PT6A-21 || 3, 1 / 1, 1 || {{cvt|550|hp|kW|disp=table}} || {{cvt|0.63|lb/hp/h|g/kW/h|disp=table}} | — || rowspan=15 | {{cvt|19|in|cm|disp=br}} || rowspan=6 | {{cvt|62|in|m|disp=br}} || {{cvt|327|lb|kg|disp=table}} || Beech Bonanza, King Air C90A/B/SE |- | PT6A-25 || 3, 1 / 1, 1 || {{cvt|550|hp|kW|disp=table}} || {{cvt|0.63|lb/hp/h|g/kW/h|disp=table}} | — || {{cvt|353|lb|kg|disp=table}} || Beech T-34C |- | PT6A-25C || 3, 1 / 1, 1 || {{cvt|750|hp|kW|disp=table}} || {{cvt|0.595|lb/hp/h|g/kW/h|disp=table}} | — || {{cvt|338|lb|kg|disp=table}} || Embraer Tucano, Pilatus PC-7, PZL-130 Orlik |- | PT6A-27 || 3, 1 / 1, 1 || {{cvt|715|hp|kW|disp=table}} || {{cvt|0.603|lb/hp/h|g/kW/h|disp=table}} | — || {{cvt|289|lb|kg|disp=table}} || Pilatus PC-6 |- | PT6A-114/A || 3, 1 / 1, 1 || {{cvt|600-675|hp|kW|disp=table}} || {{cvt|0.64|lb/hp/h|g/kW/h|disp=table}} | — || {{cvt|350|lb|kg|disp=table}} || Cessna 208 Caravan |- | PT6A-135A || 3, 1 / 1, 1 || {{cvt|750|hp|kW|disp=table}} || {{cvt|0.585|lb/hp/h|g/kW/h|disp=table}} | 7 || {{cvt|338|lb|kg|disp=table}} || Cessna Conquest, Piper Cheyenne, Beech King Air F90 |- style="background:#ebeced;" | PT6A-42 || 3, 1 / 1, 2 || {{cvt|850|hp|kW|disp=table}} || {{cvt|0.601|lb/hp/h|g/kW/h|disp=table}} | 8 || {{cvt|66.9|in|m|disp=br}} || {{cvt|403|lb|kg|disp=table}} || Beech King Air 200/B200, C-12 Huron |- style="background:#dfe0e1;" | PT6A-60A || 4, 1 / 1, 2 || {{cvt|1,050|hp|kW|disp=table}} || {{cvt|0.548|lb/hp/h|g/kW/h|disp=table}} | 8.5 || {{cvt|72.5|in|m|disp=br}} || {{cvt|487|lb|kg|disp=table}} |Beech Super King Air 300/350 |- style="background:#dfe0e1;" | PT6A-64 || 4, 1 / 1, 2 || {{cvt|700|hp|kW|disp=table}} || {{cvt|0.703|lb/hp/h|g/kW/h|disp=table}} | 8.5 || rowspan=2 | {{cvt|70|in|m|disp=br}} || {{cvt|456|lb|kg|disp=table}} || Socata TBM 700 |- style="background:#dfe0e1;" | PT6A-66 || 4, 1 / 1, 2 || {{cvt|850|hp|kW|disp=table}} || {{cvt|0.62|lb/hp/h|g/kW/h|disp=table}} | 9.5 || {{cvt|456|lb|kg|disp=table}} || Piaggio P.180 Avanti |- style="background:#dfe0e1;" | PT6A-65B || 4, 1 / 1, 2 || {{cvt|1,100|hp|kW|disp=table}} || {{cvt|0.536|lb/hp/h|g/kW/h|disp=table}} | — || rowspan=3 | {{cvt|74|in|m|disp=br}} || {{cvt|481|lb|kg|disp=table}} || Ayres Turbo-Thrush, PZL M28 Skytruck, Beech 1900/C |- style="background:#dfe0e1;" | PT6A-67B || 4, 1 / 1, 2 || {{cvt|1,200|hp|kW|disp=table}} || {{cvt|0.546|lb/hp/h|g/kW/h|disp=table}} | 10.8 || {{cvt|530|lb|kg|disp=table}} || Pilatus PC-12 |- style="background:#dfe0e1;" | PT6A-67D || 4, 1 / 1, 2 || {{cvt|1,271|hp|kW|disp=table}} || {{cvt|0.546|lb/hp/h|g/kW/h|disp=table}} | 10.8 || {{cvt|515|lb|kg|disp=table}} || Beech 1900D |- style="background:#dfe0e1;" | PT6A-68 || 4, 1 / 1, 2 || {{cvt|1,250|hp|kW|disp=table}} || {{cvt|0.54|lb/hp/h|g/kW/h|disp=table}} | — || rowspan=2 | {{cvt|72.2|in|m|disp=br}} || {{cvt|572|lb|kg|disp=table}} || Beech T-6 Texan II |- style="background:#dfe0e1;" | PT6A-68B || 4, 1 / 1, 2 || {{cvt|1,600|hp|kW|disp=table}} || {{cvt|0.54|lb/hp/h|g/kW/h|disp=table}} | — || {{cvt|575|lb|kg|disp=table}} || Pilatus PC-21 |- style="background:#c8c8c8;" | PT6B-37A || 3, 1 / 1, 1 || {{cvt|900|hp|kW|disp=table}} || {{cvt|0.584|lb/hp/h|g/kW/h|disp=table}} | — || {{cvt|19.5|in|cm|disp=br}} || {{cvt|64.4|in|m|disp=br}} || {{cvt|385|lb|kg|disp=table}} || Agusta A119 Koala |- style="background:#c8c8c8;" | PT6C-67A || 4, 1 / 1, 1 || {{cvt|1,940|hp|kW|disp=table}} || {{cvt|0.47|lb/hp/h|g/kW/h|disp=table}} | — || rowspan=2 | {{cvt|22.5|in|cm|disp=br}} || rowspan=2 | {{cvt|59.3|in|m|disp=br}} || — || — || Bell/Agusta BA609 |- style="background:#d4d4d4;" | PT6C-67C || 4, 1 / 1, 2 || {{cvt|1,100|hp|kW|disp=table}} || {{cvt|0.49|lb/hp/h|g/kW/h|disp=table}} | — || — || — || Agusta A 139 |- style="background:#bcbcbc;" | PT6T-3B/BF || 2 × 3, 1 / 1, 1 || {{cvt|1,800|hp|kW|disp=table}} || {{cvt|0.6|lb/hp/h|g/kW/h|disp=table}} | — || rowspan=4 | {{cvt|43.5|in|cm|disp=br}} || rowspan=4 | {{cvt|65.8|in|m|disp=br}} || {{cvt|668|lb|kg|disp=table}} || Bell 412/SP/HP/EP |- style="background:#bcbcbc;" | PT6T-3D/DF || 2 × 3, 1 / 1, 1 || {{cvt|1,800|hp|kW|disp=table}} || {{cvt|0.595|lb/hp/h|g/kW/h|disp=table}} | — || {{cvt|692-681|lb|kg|disp=table}} || Bell 412/SP/HP/EP |- style="background:#bcbcbc;" | PT6T-6 || 2 × 3, 1 / 1, 1 || {{cvt|1,875|hp|kW|disp=table}} || {{cvt|0.591|lb/hp/h|g/kW/h|disp=table}} | — || {{cvt|660|lb|kg|disp=table}} || Bell 212, 412/SP/HP/EP, Sikorsky S-58T |- style="background:#bcbcbc;" | PT6T-68 || 2 × 3, 1 / 1, 1 || {{cvt|1,970|hp|kW|disp=table}} || {{cvt|0.591|lb/hp/h|g/kW/h|disp=table}} | — || {{cvt|665|lb|kg|disp=table}} || Bell 412HP |} {{notelist}}

==See also== {{Portal|Aviation}} {{Aircontent |related= * Pratt & Whitney Canada PT6T |similar engines= * Garrett TPE331 * General Electric Catalyst * HAL HTSE-1200 * Klimov VK-800 * Walter M601 |lists= * List of aircraft engines |see also= }}

==References== {{Notelist-lr}}

==External links== {{Commons category|Pratt & Whitney Canada PT6}} * {{cite web |url= http://www.pwc.ca/en/engines/pt6a |publisher= Pratt & Whitney Canada |title= PT6A }} * {{cite web |url= http://www.pwc.ca/en/engines/pt6b |publisher= Pratt & Whitney Canada |title= PT6B }} * {{cite web |url= http://www.pwc.ca/en/engines/pt6c |publisher= Pratt & Whitney Canada |title= PT6C }} * {{cite web |url= http://www2.anac.gov.br/certificacao/Produtos/Espec/EA-7202-15i.pdf |title= Embraer EMB-110 type certificate |publisher= National Civil Aviation Agency of Brazil |date= 20 December 1972}} * {{cite AV media |url= https://www.youtube.com/watch?v=hQri0heCepA |title= How PT-6 Turbines Are Overhauled |publisher= AVweb |via=YouTube |date= 14 August 2015}} **{{cite web |author=Paul Bertorelli |date=August 17, 2015 |title=Video: How PT-6 Turbines Are Overhauled |website=AVweb |url=http://www.avweb.com/videos/Video-How-PT6-Turbines-Are-Overhauled-224703-1.html}}

{{DEFAULTSORT:Pratt and Whitney Canada PT6}} Category:1960s turboprop engines Category:Pratt & Whitney Canada aircraft engines Category:Mixed-compressor gas turbines