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Developing the Engines of Tomorrow

Pratt & Whitney's Flying Testbeds
Written by Blair Watson   
393-jet














One of the great things about working in civil aviation is coming across marvels of technology by surprise. Such was the case for this writer a few months ago when I was looking at aircraft photos on a Web site. I encountered some images of a jet-powered airplane with a bulbous nose, unpainted metal panels on top of the fuselage, and five engines – four large and one considerably smaller. The aircraft was identified as a Boeing 720 (of the B707 family).

According to the photographer’s text, the airplane was a “flying testbed,” with a registration of C-FETB. Using Transport Canada’s online aircraft registry, I discovered that it is owned by Pratt & Whitney Canada (P&WC), the world-famous aerospace company that designs and manufactures turbine engines. After contacting P&WC, I learned that C-FETB is one of three flying testbeds (FTBs) operated by the corporation.

P&WC opened a customer training facility in 1968 (the first of its kind), which served as an industry model. In December 2004, P&WC’s 50,000th customer was welcomed at the company’s Customer Training Centre in St-Hubert, QC. Last year, P&WC delivered its 60,000th engine – to Dassault Aviation, manufacturer of Dassault Falcon corporate jets. In addition to powerplants for business aviation, P&WC is a leader in the design and manufacture of regional turboprops and helicopter engines. It also supplies the auxiliary power units (APUs) for the Boeing 747-400 and Airbus 380.

In the past 12 years alone, P&WC has certified close to 60 turbine engines, a record that no other manufacturer has matched to date. It’s an achievement involving hundreds of flying hours using the company’s FTBs, which are operated under CAR 604. The first B720B was acquired in 1989 (and subsequently underwent airframe modifications to accommodate engines of various sizes for testing). All of P&WC’s flying testbeds were civilian airplanes prior to being re-designated for experimental test purposes. The airframes were modified by a third party in a cooperation arrangement; P&WC retained the certification ‘envelope’ and the other company carried out the modification work. The second 720B was bought in 2000, and the Boeing 747SP in 2001.

The red B720B is based at St-Hubert and is the only FTB in P&WC’s fleet that can have a turboprop engine installed (in the nose). Seventy people are employed at St- Hubert. The blue B720B and B747SP are based at Plattsburgh, NY, where there are 30 employees who support testing operations. On the blue Boeing 720B, smaller test engines of up to 17,000 lbs of thrust can be mounted on the port aft section of the fuselage. All three aircraft can have a larger engine installed on an inboard, underwing pylon. One test powerplant can be accommodated on each FTB. The B720Bs have electrical load banks, which dissipate the power generated by the test engine, installed on their upper fuselage (the metal panels). On the B747SP, the load banks are on the lower fuselage.

In terms of thrust, the size of engines that P&WC can test on its FTBs range from 1,000 to 70,000 pounds. It takes approximately 40 hours to attach a turbofan engine, and 60 hours for a turboprop powerplant and propeller (instrumentation set-up in both cases requires additional hours). The B720Bs are crewed by two pilots, one flight engineer, two test engineers, two instrumentation technicians, and one program manager. The B747SP carries two pilots, one flight engineer, two test engineers, two instrumentation technicians, and up to three program managers. Flight crew have civilian or military backgrounds (most P&WC pilots come from civil aviation). They periodically train in a simulator, and have received zero-gravity and recovery training.

Engine test flights are typically six to seven hours long, and the FTBs fly in a triangle of airspace between Mirabel, Chicoutimi and Val d’Or. Cold-weather engine testing is done at Iqualuit (the main location), Goose Bay or Churchill Falls. The FTBs are flown as testing requirements dictate, which is approximately 600 hours per year for the B720Bs and somewhat less for the B747SP. In terms of engine test parameters, on the B720Bs, 500 temperatures, 250 pressures, 250 analog signals, 32 digital channels and all normal electronic engine controls signals can be collected. The test data capture capacity on the B747SP is three times greater. Data is collected onboard and transferred to P&WC’s computers after each flight. Helicopter turbine engines and APUs are not flight-tested on the FTBs.

P&WC turbine engines are also tested on the ground in test cells, where numerous structural and performance tests must be performed in order for each powerplant to be certified by Transport Canada and validated by the FAA and EASA (European Aviation Safety Agency – formerly the Joint Aviation Authorities). Agreements involving civil aviation regulatory agencies allow P&WC to have its powerplants certified without having to repeat engine testing in the US, Europe, or elsewhere.

P&WC creates turbine engines of various sizes, which are used for business, general aviation, regional, helicopter and APU applications. In the growing Very Light Jet market, P&WC has been chosen by three manufacturers – Cessna, Eclipse Aviation and Embraer – to provide PW600-series turbofan engines for the Mustang, E500, and Phenom 100, respectively. P&WC has engineered, created, and tested turbine engines that today power more than 23,000 aircraft.

While most customers of P&WC engines are aircraft manufacturers, others specialize in turbine conversions or upgrades. In the Jan./Feb. 2006 issue of Wings, an article written by myself reported on Rocket Engineering’s turbine conversion programs involving Piper and Beech piston aircraft. The company uses PT6A engines, which the president described to me as “bulletproof.” A strong commitment to technologyreadiness, supported by rigourous flight testing, has been an important part of the work done by P&WC to make such powerplant reliability possible.

The jet engine has been a part of aviation for nearly seven decades, and the technologies and materials which have been developed during that period have resulted in increasingly fuel-efficient, dependable, and quiet turbine powerplants. Since the PT6 first took to the skies 46 years ago, P&WC has continued to improve its engine families and develop new products. The company’s tradition of making significant investments in research and development continues into the future. Already the No. 1 R&D investor in Canadian aerospace, P&WC announced last year that it would invest $1.5 billion over the next five years to develop the next generation of technologies necessary to meet future product demands.

P&WC has working relationships with Canadian universities and the National Research Council of Canada to develop and take advantage of the new materials and technologies that will be used in the aircraft of tomorrow. As in the past, Pratt & Whitney Canada’s flying testbeds will be employed to develop future turbine engines that will continue the company’s longstanding tradition of providing customers with the best that human ingenuity, hard work, and dedication to quality have to offer.
 
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