Suggested Changes in Current Noise Certification Procedures for Commercial Transport Aircraft

The FAR Part 36 Noise Certification of subsonic turbojet-powered airplanes is reviewed. As more airplanes have been tested under FAR Part 36, the FAA has implemented several amendments to the rule and has established policies that interpret sections of the rule and add new constraints to demonstration procedures. In some cases, the policies have resulted in considerable economic burden without commensurate benefits for the airport neighbor.

Based on the experience acquired at Douglas in DC-9 and DC-10 noise certification programs, and on the results of aircraft noise research conducted within and outside the Company, several opportunities have been identified for controlling certification costs without compromise of national noise abatement objectives. These opportunities involve expansion of the allowable temperature-humidity test window, expanded use of acoustical analysis rather than flight testing, and simplification in the determination of maximum sideline noise levels. Recommendations are presented for appropriate action needed to develop and implement improved procedural requirements.