Guy Norris/LOS ANGELES
General Electric has completed initial tests on a hybrid wide chord fan for the CF6-80C2 turbofan and says that it is "off and running" with development of the more powerful "G2" version for heavier versions of the Boeing 767-400 and 747-400X.
"We've just completed the preliminary design review and will lock up the design in mid-1999," says CF6 project general manager, Roger Seager. "We have funding and the first engine to test is due in August 2000," he adds. The upgraded CF6-80C2G2 is now scheduled to be flight tested at the end of 2001 with entry-into-service planned for "mid to late" 2002.
The go-ahead of the growth variant was sanctioned by GE in March, and gives the company new options to tackle three key target areas required for the 747-400X, namely acoustics, fuel consumption and thrust. Yet the G2 allows GE to offer a solution using the same pylon and nacelle as the current CF6, and is also applicable to higher weight 767-400s.
Despite the development, GE does not see a clash with the GP7000 joint venture with Pratt & Whitney. The G2 is ostensibly aimed at the initial growth version of the 747-400X, with a 426,800-435,800kg (940,000-960,000lb) take-off weight, while the GP7000 is aimed at the subsequent wing-root insert version as well as the Airbus Industrie A3XX.
Initial birdstrike tests on the hybrid blade, recently conducted in a static rig at GE's Evendale plant in Ohio, have produced "very good results", says Seager. The new fan will help expand the thrust range from the 283kN (63,500lb) planned with the new -B8F version (for the 767-400ER), to 298kN.
Seager says that the G2 blade is made of solid forged titanium which is then "hollowed out" and filled with composite materials. Other key features include proprietary "innovative" core and fan flow mixing techniques as well as sloping outlet guide vanes to reduce noise, and extensive use of "3-D" aerodynamic modifications to the aft stages of the high pressure compressor and turbine. These latter modifications are expected to generate between 1.5% and 2% improvement in specific fuel consumption, says Seager.
Meanwhile, the development programme for the new 767 engines is "on track for certification in the first quarter of 1999" says Seager. First engines for flight testing on the initial -400 will be delivered to Boeing's Everett site in mid-1999 with handover to launch customer Delta Air Lines due in May 2000. Certification is based around the more powerful -B8F version and "-will read across" to the lower thrust -B7F1, he says.
Source: Flight International
