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  • The Little Engine That Could ... and Did
    Posted by William Garvey 9:37 AM on Oct 30, 2012

    The good folks at Pratt & Whitney Canada are getting ready for a big, year-long birthday bash to celebrate a product that saved it, sustained it and made "little Pratt" the envy of the propulsion world -- a Jet A burner with the decidedly unpoetic moniker, the PT6.

    In its pre-turbine days, the role of the Quebec-based outfit was manufacturing and servicing the company's Wasp radial. But by the mid-1950s, it was clear that the turbine engine would soon reign supreme, and Longueuil's leaders knew they had to embrace it or die.

    With Big Pratt in East Hartford, Conn., focused on big engines -- its J57/JT3 powered everything from the B-52 to the Boeing 707 -- Pratt Canada focused on small. Despite its lack of turbine experience and absence of any ready platforms for such an engine, it pressed on.

    Studies of the general aviation marketplace, including discussions with Beech, Bell, Cessna and Piper, indicated that a 500 shp turboprop/turboshaft engine with high reliability held the greatest promise.

    The engine that emerged -- the company's sixth propeller turbine design, or PT6, for short -- featured a free turbine that could be mated with a simple, low-drag propeller and eliminated the need for a clutch in a helicopter. Its opposed shaft provided maintainers easy access to the hot section. And the air intake was aft and exhaust forward, making for quieter airplanes and reducing FOD vulnerability.

    The engine took flight in May 1961 and won certification two years later.

    Beech Aircraft was the first taker, mating the little Canadian engine with its Queen Air, and then enticed the U.S. Army to buy a fleet of what the service called the U-21 Ute. The process helped launch the King Air. Since then, Beechcraft has delivered some 7,000 of the type, making it the PT6's most significant customer.

    A host of other OEMs have also come to embrace the sturdy, reliable powerplant, installing it on something like 150 different models of aircraft and counting. It's been so widely adapted in part because the engine's design proved wonderfully scalable. Its three-dozen iterations range in power from 500 shp to more than 2000 shp.

    To that last point, Denis Parisien, VP-General Aviation at PWC, told reporters at the NBAA Convention that, "We're very proud of the PT6, but it's not just one engine."

    The company plans to mark the PT6's golden anniversary with a series of celebrations, culminating in a December delivery 50 years to the month since certification. Pratt says it's not sure which OEM will get the golden mill, something that's hard to believe seeing as how they've had five decades to prepare. 

    Tags: ba99, nbaa12

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