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Aviation History
2003
2003 - 1103.PDF
SMALL WONDER ir story Embraer's choice of General Electric's CF34 to power its 170 regional jet has been the latest success for a venerable family of small engines GUY NORRIS/LOS ANGELES Almost 30 years after the first into service on Embraer's 170 regional jet. variant of the General Electric The CF34-8E secured its place on the CF34 series entered service as Brazilian airliner in mid-1999 after a battle the military TF34, the latest with the SPW14, a conceptual engine pro-member of this small, but highly posed jointly by Snecma and Pratt & successful turbofan family is poised to go Whitney Canada. "It was a tough chal- The CF34-8E selected for the 170 had the major advantage of being based on the > proven -8C1 lenge because, with a paper engine, you can make it speak to any requirement," says GE's small commercial engines gen eral manager Charles Blankenship. Despite the promises of its opponent, the CF34 had some major aces up its sleeve. Apart from highly competitive offerings on product support, life-cycle costs, thrust-to-weight ratio and price, the 14,2001b-thrust -8E variant offered to Embraer was based fundamentally on the existing -8C1. "We had a proven platform with the -8C1, which was then in the mid- to late stages of certification," says Blankenship. "The main thing was it was running and flying." The other ace, or so it seemed at the time, was the engine's recent selection for the now-defunct Fairchild Dornier 728. "This meant we had started work for an underwing application, so on a couple of fronts we had some state of maturity," says Blankenship. "The 728 selection was also important to Embraer because it took a couple of months out of the development cycle." The Brazilian company's timetable was challenging, adds Blankenship. "They wanted it to fly in no time." Double the thrust Like the -8C1, the -8E incorporates the larger 1.17m (46.2in)-diameter wide chord fan that was introduced to virtually double the thrust capability of the -8 series over the baseline -3. The fan generates higher airflow and an increased pressure ratio, and is contained by a Kevlar reinforced ring. The 10-stage high-pressure (HP) com pressor is based on that of the F414 mili tary engine, and the machined-ring, bolted-dome combustor is derived from a mix of predecessors, including the F404, CF6 and the CF34 family itself. The first three stages of the HP compressor are blisks, which help to reduce weight and minimise inter-stage leakage, says GE. Aft of the combustor, the two-stage HP turbine feeds into a four-stage low-pressure (LP) turbine with improved three-dimen sional aerodynamics and low parts count. The -8E is also full-authority digital engine (FADEC) controlled, with automatic start ing, hot-start prevention, automatic power reserve (APR) detection/activation, auto matic in-flight ignition, and continuous self-test and built-in diagnostics. To meet the slightly increased thrust needs of the Embraer 170, as well as the 728 and Bombardier's CRJ900, GE embarked on a series of "thrust bump" changes to the baseline -8C1. Launched in 1999, the result ing "-8 Growth" programme simultane ously embraced changes for all three new applications, and was the first such effort ever undertaken in commercial jet engine development. Key features included the www.flightinternational.com FLIGHT INTERNATIONAL 13-19 MAY 2003 63
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