Interpretation ID: aiam2251
Staff Engineer
Blue Bird Body Company
P.O. Box 937
Fort Valley
GA 31030;
Dear Mr. Milby: This responds to Blue Bird Body Company's March 15, 1976, request fo confirmation that calculation of the material tensile strength of body panels under S6.2(a) of Standard No. 221, *School Bus Body Joint Strength*, is based on the minimum thickness permitted by American Society for Testing and Materials (ASTM) Standard 525 for the thickness specified in ordering the material. This response also reflects the April 1, 1976, meeting held between Blue Bird representatives and National Highway Traffic Safety Administration (NHTSA) personnel at Department of Transportation headquarters.; Under ASTM standards, the thickness of listed materials is permitted t vary from the specified or 'nominal' thickness by a small amount. If the thickness tolerance of a material is specified by the ASTM, the NHTSA bases its determination of thickness on the 'minimum thickness' specified for that material in the 1973 edition of the Annual Book of ASTM Standards. If the thickness tolerance of a material is not specified by the ASTM, the NHTSA uses the minimum thickness permitted by the school bus manufacturer's material specification.; Yours truly, Stephen P. Wood, Assistant Chief Counsel