Reduction of JT8D powered aircraft noise by engine refanning

The purpose of the Refan Program is to establish the technical feasibility of substantially reducing the noise levels of existing JT8D powered aircraft. This would be accomplished by retrofitting the existing fleet with quieter refan engines and new acoustically treated nacelles. No major technical problems exist that preclude the development and installation of refanned engines on aircraft currently powered by the JT8D engine. The refan concept is technically feasible and provides calculated noise reductions of from 7 to 8 EPNdB for the B727-200 aircraft and from 10 to 12 EPNdB for the DC-9-32 aircraft at the FAR Part 36 measuring stations. Corresponding reductions in the 90 EPNdB footprint area are estimated to vary from about 70 percent for the DC-9 to about 80 percent for the B727.