A significant portion of the NASA-sponsored Performance Improvement Program for the CF6 engine was the development of an improved fan concept. This involved aerodynamic redesign of the CF6 fan blade to increase fan efficiency while retaining the mechanical integrity, operability, and acoustic characteristics of the existing blade. A further improvement in performance was obtained by adding a fan case stiffener ring to decouple blade-case vibrational characteristics, permitting a significant reduction in running tip clearance. Engine testing was performed to establish the performance, mechanical and acoustic properties of the new design relative to the current fan, and to establish power management characteristics for the CF6-50C2/E2 engine. A significant improvement in cruise power SFC of 1.8 percent was demonstrated in Sea Level testing projected to altitude flight conditions. The improved fan has been certified in the CF6-50C2/E2 engines and is now in commercial service on the Boeing 747, Douglas DC10-30 and Airbus Industrie A300B aircraft. The improved fan will also be incorporated in the CF6-6K engine and provides a basis for further improvements that will be incorporated in other General Electric commercial offerings, such as the CF6-80 and CF6-32.

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