Interpretation ID: 17893a.df

Mr. Bobby Puett
President
Diversified Testing Laboratories, Inc.
336 West Front Street
P.O. Box 4004
Burlington, North Carolina 27215

Dear Mr. Puett:

This responds to your letter concerning the test procedures in Federal Motor Vehicle Safety Standard No. 302, Flammability of Interior Materials. I apologize for the delay in my response.

You explain that you tested a lightweight coated fabric both with and without support wires and had dramatically different test results. You state that when you tested the fabric without the support wires, the fabric burned at a rate of 15 inches per minute and failed the test (the standard limits the burn rate to not more than 4 inches per minute). In addition, the testing specimen bent slightly during the test. You explain further that when you tested the fabric with support wires and a U-shaped frame as specified in Standard 302, the fabric "ignited but self-extinguished upon contact with the second cross wire from the end of the frame" and passed the test. You express concern over the variation in test results and ask when to use a frame with support wires and where to place the support wires during testing.

Section S5.1.3 of Standard 302 states, in relevant part, that:

A specimen that softens and bends at the flaming end so as to cause erratic burning is kept horizontal by supports consisting of thin, heat resistant wires, spanning the width of the U-shaped frame under the specimen at 1-inch intervals. A device that may be used for supporting this type of material is an additional U-shaped frame, wider than the U-shaped frame containing the specimen, spanned by 10--mil wires of heat resistant composition at 1-inch intervals, inserted over the bottom U-shaped frame.

The National Highway Traffic Safety Administration cannot specify, outside of the context of a compliance test, whether it will use support wires to test your material. As a matter of policy, a decision to use wires is made only in the context of compliance testing. The agency decides to use wires based on observations made in previously-conducted compliance tests of the specimen, or on the agency's knowledge of or testing experience with components that are highly similar to a test specimen. We note that the test condition noted in S5.1.3 should be read as a whole. Thus, the supplemental supports are only to be used if the specimen (1) softens and bends at the flaming end (2) so as to cause erratic burning. The agency does not use support wires in situations of erratic burning alone.

If you have any questions, please contact Nicole Fradette at this address or by phone at (202) 366-2992.

Sincerely,
Frank Seales, Jr.
Chief Counsel
ref:302
d.11/24/98