Category Archives: PT6A Engine

The PT6A-50 Powered De Havilland Canada DASH-7

During the 1950s and 1960s, the aircraft manufacturer De Havilland Canada (DHC) acquired extensive experience in the construction of small and medium capacity transports with short takeoff & landing (STOL) capabilities, such as the “Otter”, “Twin Otter”, “Caribou”, and “Buffalo”. In the early 1970s, DHC decided to create a four-engine turboprop medium STOL airliner, which emerged as the “DHC-7” AKA “DASH-7”. The DASH-7 was only built in modest numbers, though it did prove useful as a military surveillance platform. DHC followed it with a twin-turboprop airliner, the “DHC-8” AKA “DASH-8”, which proved much more successful. This document provides a history and description of the DASH-7 and DASH-8.


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A Quick Look at the Twin PT6A Powered Cheyenne II & IIXL

In the mid-1960s, Piper, noting the success of Beech’s King Air, decided to explore the possibility of producing its own twin turboprop. The manufacturer hired legendary aircraft designer Ed Swearingen to retrofit a Piper PA–31P pressurized Navajo with 550-shaft-horsepower Pratt & Whitney Canada PT6A-20 turboprops. After a successful first flight in April 1967 and further tests indicated that the Pratt powerplant and Piper airframe were a good match, the PA–31T Cheyenne was launched.

The Cheyenne was a simple and reliable entry-level turboprop that was more affordable and faster than the King Air 90. However, the Cheyenne’s smaller cabin could only accommodate two pilots and four passengers—plus a fifth passenger if the belted potty seat were used. Baggage space was limited, but the airplane could operate from relatively short runways and be flown by a single pilot.

Piper Cheyenne II from

The initial production model of the Cheyenne was powered by two 620-shaft-horsepower Pratt & Whitney Canada PT6A-28 turboprops and included 30-gallon wingtip fuel tanks. Dual King Gold Crown avionics were standard. The Cheyenne first flew in October 1969 and was certificated in May 1972. Cheyenne deliveries began in 1974.

When Piper introduced the lower-powered and less expensive Cheyenne I in 1978, the manufacturer renamed its original twin turboprop the Cheyenne II. Essentially the only difference between the original Cheyenne and the Cheyenne II were some cabin configuration changes. The stretched PA–31T2 Cheyenne IIXL, which had a two-foot-longer fuselage than the original Cheyenne, entered production in 1981. The IIXL has an extra cabin window on the left side, a nearly 500-pound higher max takeoff weight, and is powered by more powerful 750-shaft-horsepower PT6A-135s. Besides offering more interior room, the IIXL’s longer fuselage eliminated the need for the stability augmentation system.

A Piper Cheyenne XLII from

Over the years, many enhancements for the Cheyenne II have been developed, with the most notable being Blackhawk Modifications, Inc.’s XP engine upgrade, which involves replacing the Cheyenne’s original engines with new 750-shaft-horsepower PT6A-135A turboprop engines. The simple bolt-on upgrade enables operators to cruise approximately 20 knots faster.

The PT6A-135A engine was also the cornerstone of the Super Cheyenne conversion, which was offered by T-G Aviation of Hamilton, Ontario, Canada. Some Cheyenne operators have also boosted the speed of their airplanes by fitting them with cowl/ram air and exhaust stack aftermarket kits.

In addition, numerous panel upgrades have been developed for the Cheyenne II, including installation of lighter, more capable new-generation avionics from Aspen, Cobham (Chelton and S-TEC), and Garmin.

Piper built a total of 526 original Cheyennes and Cheyenne IIs, and 228 remain on the FAA registry, according to Vref. Prices range from $310,000 for a 1974 model to $520,000 for a 1983 model. Of the 81 Cheyenne IIXLs produced, 46 remain on the FAA registry. Prices range from $620,000 for a 1981 model to $680,000 for a 1984 model.


Cheyenne II

Engines | Two Pratt & Whitney PT6A-28s, rated at 620 shp 
Seats | Seats: Up to 8 (including two pilots)
Max takeoff weight | 9,000 lb
Max cruise speed | 277 kt
Takeoff distance (over 50 ft obstacle) | 1,980 ft
Range | 1,195 nm
Wingspan | 42 ft, 8 in
Length | 34 ft, 8 in
Height | 12 ft, 9 in

Cheyenne IIXL

Engines | Two Pratt & Whitney PT6A-135s, rated at 750 shp
Seats | Seats: Up to 8 (including two pilots)
Max takeoff weight | 9,474 lb
Max cruise speed | 273 kt
Takeoff distance | 2,042 ft
Range | 1,060 nm
Wingspan | 42 ft, 8 in
Length | 36 ft, 8 in
Height | 12 ft, 9 in

Information via AOPA

A Look at the PT6A-42 Blackhawk XP42A

The Cessna Caravan always needed more power, and competition to provide it was established with the supplemental type certificate (STC) awarded in 2013 to Blackhawk Modifications to install the 850-shp Pratt & Whitney Canada PT6-42A in the short-fuselage 208A model as the XP42A.

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A Flying Swiss Army Knife: The Many Faces Of The Pilatus PC–6 Porter

It’s a missionary and a mercenary. A soldier and a spy. A record-setter and an also-ran. After 60 years of continuous production, the Pilatus PC–6 Porter, a legendary Swiss turboprop that has played more supporting roles than Kevin Bacon, will cease production in 2019.

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The Douglas DC-3: 85 Years and Going Strong

The Douglas DC-3 Doesn’t Know the Meaning of the Word “Quit”

The same year the German airship Hindenburg crossed the Atlantic, the still-flying-today Douglas DC-3 was introduced to the world. The DC-3 is widely viewed as one of the most significant transport aircraft in history, due to its massive and long-lasting impact on the airline industry, and aerospace engineering. I got the chance to interview Ric Hallquist, the retired Chief DC-3 Pilot for Missionary Flights International who flew and worked on the beefy twin engine transport plane for over 30 years.

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What is a Hot Section Inspection & Why It’s Important to PT6A Engine Longevity

The Pratt & Whitney PT6 engine has been in use since 1961 and has since logged more than 380 million flight hours, the equivalent of about 250,000 round-trips to the moon.   The most advanced PT6A engine family includes three power levels, “Small”, “Medium”, and “Large” that all have the advantage of turbine cooling, aerodynamic design, and advanced technologies in materials.  Keeping these engines running efficiently and safely wouldn’t be possible without a periodic Hot Section Inspection.

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