Tag Archives: Pratt & Whitney PT6A

Pratt & Whitney PT6 Celebrates 50 Years Part 2

The 12 engineers who gathered in 1957 to build the first turbine engine for Pratt & Whitney, and who can be considered the brains behind the PT6, created an engine in two sections that are easily separated for maintenance.  The creation of these engineers led to aviation history.

First Flight

beechcraft The PT6 first flew on May 30, 1961 as the power for a Beech 18 aircraft in Ontario, Canada.  Full-scale production began in 1963, and in December of that year, Pratt & Whitney shipped the first PT6 to Beech Aircraft Company to power their Beech 87, an aircraft that later became the King Air.  Experts said that the PT6 was an innovative gas turbine representing significant advances in technology, with great advantages over traditional piston-driven engines.  Much of this benefit was due to the higher power to weight ratio the PT6 offered.

Piper Milestone


In 1967, the Piper PA-31 Navajo first flew using a PT6 engine.  Despite enormous success building light aircraft engines since the 1930’s, Piper fought the adoption of turbine engines in their aircraft.  Instead, they preferred the more traditional piston-driven engines.  This marked an important milestone for Pratt & Whitney who had attempted to get Piper to switch to their turbine engines for many years.

Other Applications

 Although the Pratt & Whitney PT6 became the most popular engine for powering high-performance airplanes and helicopters, in its early days an industrial version known as the ST6 appeared in some interesting applications.  In 1966, the Thunderbird, a 10-meter boat owned by Jim Wynn, a racing-boat champion, used two ST6 engines.  It was one of only two boats out of 31 to complete the Sam Griffith Memorial Race on February 22, 1966, and although it came in first, it was denied official recognition as it was considered experimental.  The turbine engine powered Turbo Train was designed to provide passenger service between New York and Boston, and was supposed to be a centerpiece at Expo 67.  Unfortunately, it was not completed in time for the Expo, but by 1973, was regularly travelling at speeds of nearly 193 km in the Montreal-Toronto corridor.  In 1978, Andy Granatelli, President of STP, installed an ST6 in his custom-made Corvette after it was banned from use in the STP Indy cars by the USAC.

The PT6 not only has a long and colorful history as an aircraft engine, but in powering other types of vehicles as well.  Learn more about the PT6 and find out more about the aircraft maintenance services at Covington Aircraft by contacting them online or by phone today.

PT6 Celebrates Fifty Years Part 1

When it was developed in 1963, the PT6 was the first turboprop engine rated at 450 shaft horsepower, impressing Beechcraft to the point that the company chose to install the engine in their King Air line of turboprop twins.  Fast-forward 50 years, and Beechcraft still choose the PT6, although of ever-increasing power ratings, to power their engines.

 Before The PT6

beechcraftPratt & Whitney began development of the PT6 in the late 1950’s in an attempt to replace the manufacturer’s Wasp radial engines, developed during in the 1930’s.  In 1925, Frederick Rentschler, President of Wright Aeronautical, approached his brother, Gordon, and Edward Deeds, who were both on the board of Niles Bement Pond, convincing them that Pratt & Whitney Machine Tool, a subsidiary of Niles, should fund the creation of a new aircraft engine Rentschler and a colleage, George Mead, were developing.  The engine was to be a large, air-cooled radial design.  The executives at Pratt & Whitney saw an opportunity for growth and lent Rentschler $250,000, the use of the Pratt & Whitney name and space in their building to begin creating the new engine.  Rentschler left Wright Aeronautical and took over operations of Pratt & Whitney Aircraft Division, The first of the Wasp series debuted on December 24, 1925, quickly becoming one of the most widely used aircraft engines in the industry due to their superior speed, rate of climb and reliability.  Charles Lindbergh and Ameila Earhart both set records in Wasp-powered aircraft.

Wasp to Hornet

 With the development of the PT6 still a few decades away, Pratt & Whitney created the next line of radial engines, the Hornet, rated at 525 horsepower.  The dependability of both the Wasp and the Hornet made them very popular among commercial aircraft, and as the public use of air travel increased, so did the demand for Pratt & Whitney engines.  As it became apparent that the United States would enter World War II, President Franklin D. Roosevelt called on manufacturers to produce 50,000 aircraft a year for military use, requiring Pratt & Whitney to expand its workforce from 3,000 to 40,000.  Throughout the war, Pratt & Whitney continued to innovate, until, by the end of the war, their largest engine provided 3,600 horsepower.  However, radial engines were slowly being replaced by lighter turboprop engines.

Vision of the PT6

In 1957, Pratt & Whitney saw an opportunity to channel profits from the piston engine spare parts business to the development of smaller gas turbine engines than those currently being manufactured in the United States. The company gathered a team of 12 young engineers after conducting market studies that found there was a need for a 500 shaft horsepower engine that could replace piston engines, such as the Wasp and Hornet.  In December 1963, Pratt & Whitney shipped the first of the PT6 series, the PT6A-6, a highly innovative gas turbine representing technology advances that were significant at the time.  Because gas turbines have a higher power to weight ratio than piston engines, the PT6 was perfect for aviation engines.

pt6aThe PT6 has enjoyed a rich and colorful history since it began production in 1963, and Pratt & Whitney is proud to celebrate the 50th anniversary of this timeless aircraft engine.  Learn more about the colorful past, pioneers who flew this engine and continuing evolution of an engine ahead of its time.  For more information on the PT6 or about aircraft maintenance, contact Covington Aircraft online or by telephone today.

Pratt & Whitney PT6A Emergency AD Issued


September 15, 2011


Pratt & Whitney PT6A Emergency AD Issued

pw-pt6aOn Sept. 15, 2011, the FAA published an Emergency Airworthiness Directive (EAD) for certain Pratt & Whitney PT6A engines. The emergency AD, numbered 2011-20-51, was prompted by failures of certain first stage reduction sun gears manufactured by Timken Alcor Aerospace Technologies, Inc. (TAATI) under a part manufacturer approval (PMA). The engines affected are PT6A-15AG, -27, -28, -34, -34AG, -34B and -36. About 80 of these gears are suspected to have the anomaly and about half have already been taken out of service. If not corrected, this condition could result in failure of the shaft portion of the sun gear which will result in engine shutdown.

The emergency AD is effective upon receipt. This AD applies to the listed engines which have had maintenance done to the power section module involving first stage reduction sun gear replacement since Feb. 3, 2010 having the TAATI sun gear, part number (P/N) E3024765, serial numbers (S/Ns) PC5-091 through PC5-176 installed. For affected engines, remove the replacement first stage reduction sun gear and the interacting planet gear within 15 operating hours or 15 days after receipt of this AD.

NAAA recommends you read the AD carefully to determine the action or actions required to comply with this Emergency Airworthiness Directive.

For more information, visit Covington Aircraft’s website and give us a call.

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