Pratt & Whitney Canada PT6

Pratt & Whitney Canada PT6

A PT6A-67D on a Beechcraft 1900D. One of the gas outlet nozzles at the front is clearly visible

A PT6T-3B in a Bell 412 helicopter

The Pratt & Whitney Canada PT6 (military designation Pratt & Whitney Canada T74 ) is a shaft engine from the Canadian aircraft engine manufacturer Pratt & Whitney Canada . It is manufactured for use with propellers (PT6A) as well as for powering helicopters (PT6B, C and T). The PT6 is extremely successful economically. The mass production began in 1964, as of 5/2007 almost 43,500 of these engines in 88 versions (65 of them PT6A) were produced. Of these, the turboprop versions with low power carry the identification A-11 to A-36 or A-110 to A-135, the medium power A-40 to A-45R and the high power A-60 to A-68.

history

The first prototypes were put to the test in November 1959. First flight attempts began in May 1961 with a Beech 18 , in which the engine was installed in the nose of the machine. In July 1961 a military T74 helicopter engine was tested for the first time in a Hiller Ten99 . The license for civil aviation was granted in 1963. In December 1968 MAN Turbo acquired a production license for the PT6A-27 in order to be able to build the engine in Germany.

The first production model, the PT6A-6, had an output of 404 kW (approx. 550 PS), while the currently most powerful version (PT6A-67F) already delivers a shaft output of 1,213 kW (approx. 1,650 PS). The mean time between overhaul is up to 6000 operating hours.

The version PT6T "Twin Pac" (military designation: T400) is a helicopter engine in which two partially improved PT6A (for example with PT6T-3 two PT6A-34) are flanged to a common gearbox, which is connected to a single output shaft with 6,000 or 6,600 rpm output speed. This power unit first ran in July 1968 and was tested in a Bell 212 from April 1969 . They are produced in three series PT6T-3, -6 and -9, which differ in output power.

The PT6B version was created on the basis of the PT6A by adopting the improvements of the PT6T series.

In 1966 a variant of the PT6 was developed to drive the light express train UAC TurboTrain in the USA. In 1968, a contract was signed with Lockheed to supply 156 auxiliary power units for the Lockheed L-1011 TriStar . These drives based on the PT6 were given the designation ST6 ( Stationary Turbine ).

In the PT6C version, the reduction gear was dispensed with, so that the turbine drove the output shaft directly. The latest versions (e.g. PT6C-67, which is based on the PT6A-67) are controlled via a FADEC system. At least three variants PT6C-67A, -67C and -67E are produced, which differ in their output power. The PT6C-67A with 1447 kW power is intended to drive the AgustaWestland AW609 tiltrotor .

construction

The specialty of this engine is that it is flown through from the rear to the front when viewed in the direction of flight. The intake air is drawn in in the rear part of the engine over the entire circumference through a protective grille. The compressor, which is arranged at the rear of the gas generator shaft, consists of three, with PT6C and more powerful PT6A engines, four axial stages and a final radial compressor wheel . The compressed air then passes through a reverse annular combustion chamber with an S-shaped cross section and concentrically around the turbine housing, into which the fuel is injected through 14 nozzles. The working gas then flows through a single-stage axial turbine from back to front, which drives the compressor and a single-stage or, in the case of high-performance turboprops, two-stage axial turbine for the shaft power, which is arranged on a separate forward shaft. In most variants, the gas then escapes into the open behind the output end through two opposite, laterally attached outlet nozzles; in some variants, other exhaust gas ducts are provided, e.g. B with the PT6A-114 for the Cessna 208 Caravan with an exhaust pipe sloping downwards or the PT6-T for helicopters. The turboprop variants have a two-stage propeller gear at the front end, while the versions for helicopters have a single-stage reduction gear.

Technical specifications

Surname	PT6A-11AG	PT6A-50	PT6A-67P	PT6A-68C	PT6B-36A	PT6B-37A	PT6C-67B	PT6C-67C	PT6T-6B
diameter	483 mm				825 mm × 495 mm	495 mm	584 mm		825 mm × 1105 mm
length	1.58 m	1.73 m	1.93 m	1.83 m	1.5 m	1.63 m	1.50 m		1.67 m
Weight		193 kg			169 kg	172 kg		205 kg
Starting power	550 kW (approx. 750 PS)	705 kW (approx. 960 PS)	895 kW (approx. 1,220 hp)	1,175 kW (approx. 1,600 PS)	732 kW (approx. 1,000 PS)	747 kW (approx. 1,020 hp)	895 kW (approx. 1,220 hp)	1,252 kW (approx. 1,700 PS)	1,469 kW (approx. 2,000 PS)
specific fuel consumption		353 g / ekWh			263 g / ekWh	265 g / ekWh			273 g / ekWh

Web links

Commons : Pratt & Whitney Canada PT6  - Collection of pictures, videos and audio files

• Pratt & Whitney Canada: Overview of the PT6A Series (English)
• Pratt & Whitney Canada: Overview of PT6C-series (English)
• Type certification of the PT6A-41 - EASA-TCDS-E.078 (PDF; 190 kB)
• Type certification of the PT6A-67 - EASA-TCDS-E.008 (PDF; 188 kB)
• Type certification of the PT6A-100 - EASA-TCDS-E.094 (PDF; 267 kB)
• Type certification of the PT6B-36 - EASA-TCDS-E.039 (PDF; 190 kB)
• Type certification of the PT6C-67 - EASA-TCDS-E.022 (PDF; 209 kB)
• Detailed information on the PT6 turbine ( Memento from July 20, 2012 in the Internet Archive )
• Model overview PT6A series (English, PDF, 317 kB)

swell

• Jane's all the world's aircraft. 1956/57, 1969/70.
• Klaus L. Schulte: Brief history of the PT6. KLS Publishing, 2007.

Individual evidence

1. ↑ PT6T Twin-Pac on the manufacturer's website , in English, accessed on July 15, 2020
2. ↑ Flightglobal entry via PT6C 67A  ( page no longer available , search in web archives )  Info: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice. Retrieved April 19, 2012  
3. ↑ Archive link ( Memento of the original dated May 8, 2015 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.