Interpretation ID: nht76-5.4

DATE: 07/23/76

FROM: HERLIHY FOR S.P. WOOD -- NHTSA

TO: Celanese Fibers Marketing Company

TITLE: FMVSS INTERPRETATION

TEXT: This responds to your March 19, 1976, recommendation that paragraph S5.1(e) of Standard No. 209, Seat Belt Assemblies, be amended to clarify that the temperature specified in the "resistance to light" test procedure is intended to be "black panel" temperature rather than "bare bulb" temperature.

The procedures outlined in Standard No. 209 for the "resistance to light" test were adopted from the Bureau Standard's procedures for testing seat belts. The standard was developed by an industry and government group, which included Celanese Fibers, as a simplification and improvement of the A.S.T.M. Designation E42-64 procedure. The "resistance to light" test was established to test nylon webbing, which was the standard material used in seat belt webbing at that time.

We recognize, however, that the industry now uses decron and polyester materials in seat belt webbing, and that the Standard 209 test procedure developed to test nylon does not give meaningful results for these new materials. Therefore, the National Highway Traffic Safety Administration does not enforce the requirements of paragraph S5.1(e) of Standard No. 209 in the case of seat belt webbing made of dacrons and polyesters, and will not until appropriate testing procedures can be developed and incorporated in the standard for these new materials.

Procedures for testing systems containing materials other than nylon are under development and we plan to initiate rulemaking to incorporate these procedures into standard 209. You should understand that our commencement of a rulemaking proceeding does not signify that the rule in question will be issued. A decision as to the issuance of the rule is made on the basis of all available information developed in the course of the rulemaking proceeding, in accordance with statutory criteria.

We would appreciate any data you may be able to provide regarding colorfastness tests for fabrics other than nylon.

SINCERELY,