Final Report; January 2002 ¿ April 2002

NTL-AVIATION-AVIATION ; NTL-AVIATION-Aviation Energy and Environment ;

The Society of Automotive Engineers’ (SAE) Aerospace Recommended Practice (ARP) No. 866A (866A), and a procedure utilizing pure-tone absorption equations developed in support of the International Organization for Standardization’s (ISO) 9613-1 and the American National Standards Institute’s (ANSI) S1.26-1995, are compared and a sensitivity analysis undertaken. The ISO and ANSI equations are identical to each other. Thirteen takeoff and two approach spectra for aircraft were utilized in the analysis, as well as one takeoff, two approach, and three flyover spectra for helicopters. As-measured spectra were processed at 10 standard distances between 200 ft. and 25,000 ft., and at five different temperature/ relative humidity (RH) combinations, to generate adjusted spectra and associated LASmx values. The focus of the study is a refined version of the ISO/ANSI adjustment procedure developed specifically for application to one-third octave-level data.

Volpe