Noise Contour Comparison of Stage 3 Hushkit Options for Boeing 727-200

Because of the hushkitting of older Stage 2 aircraft such as the Boeing 727 to meet Part 36 Stage 3 requirements of Federal Aviation Regulations (FARs), up to 1,000 older and noisier aircraft may still be flying in the United States after December 31, 1999. Many noise studies with FAA’s Integrated Noise Model (INM) have predicted a significant decrease in the noise contours after this date, anticipating replacement of most Stage 2 aircraft with modern Stage 3 aircraft, such as Boeing 737-700 series, Boeing 757-200, and Airbus A320 series aircraft. The INM noise footprints of a Boeing 727-200 with the Federal Express Aviation Services Inc. (FedEx) and Raisbeck Stage 3 hushkit treatments were compared with that of an unmodified Boeing 727-200 as well as that of a Boeing 757-200, which is representative of a true new-technology Stage 3 aircraft. Although the FedEx and Raisbeck Stage 3 kits are extremely cost-effective solutions for achievement of Stage 3 compliance under FAR Part 36, the real benefits to the community are somewhat limited compared with those from an aircraft designed from the outset as a Stage 3 aircraft.