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Interpretation ID: Davis_8129-2

    Douglas Davis, Vice President
    Davis Aircraft Products Co. , Inc.
    1150 Walnut Avenue
    Bohemia, NY 11716-0525


    Dear Mr. Davis:

    This responds to your letter in which you ask about the load requirements under Federal Motor Vehicle Safety Standard (FMVSS) No. 209, Seat belt assemblies. In your letter you suggest that there is an "overtest" condition with regard to one of the upper torso restraint components under the agencys test procedure (TP-209-05, January 17, 2003). As explained below, FMVSS No. 209 requires that a D-ring withstand the required force in the context of the test procedure specified in the standard, which is reflected in TP-209-05. As such, the procedure illustrated in TP-209-05 does not result in an "overtest".

    FMVSS No. 209 specifies requirements for seat belt assemblies to ensure that such assemblies provide occupants with a minimum level of protection in a crash. As noted in your letter, S4.4 of the standard establishes the performance requirements for seat belt assemblies. S4.4(b)(2) requires structural components in an upper torso restraint to withstand a force of not less than 6,672 N when tested in accordance with S5.3(b) of the standard. The S5.3 test procedure applicable to S4.4(b)(2) is illustrated in Figure 10 of the laboratory test procedure, TP-209-05 (copy enclosed). We note that a revised version of the test procedure has been issued, TP-209-05 (August 22, 2005), but that no revisions have been made to Figure 10.

    In your letter, you stated that under the test procedure illustrated in TP-209-05 Figure 10, a D-ring would experience a resultant force greater than 6,672 N. You stated that this resultant force created "an over test condition".

    We disagree that the test procedure illustrated in TP-209-05 results in "an over test condition". As indicated above, S4.4(b) specifies that, with certain exceptions not relevant to your question, the components of a Type 2 seat belt assembly must meet specified requirements "when tested by the procedure specified in S5.3(b)". (Emphasis added. ) While S4.4(b) requires certain components (including a D-ring) in the upper torso restraint to withstand a force of not less than 6,672 N, the procedure with respect to how that force is applied is specified in S5.3(b).

    S5.3(b)(2) specifies that the 6,672 N force is applied as a tensile force in the manner prescribed in S5.3(b)(1). Through referencing S5.3(a)(2), S5.3(b)(1) specifies that the assemblys attaching bolts are attached to an anchorage bar in a manner that results in the angle nearest to 90 degrees between webbing and attachment hardware, except that eye-bolts are vertical. This procedure is represented in Figure 10 of TP-209-05.

    We recognize that the resultant force exerted on a D-ring is greater than the tensile force applied to the seat belt assembly. However, S4.4(b)s performance requirement is written in the context of a specified test procedure for the entire seat belt assembly. The higher force experienced by a D-ring is the result of the specified test procedure. As such, the illustrated test procedure does not result in an "overtest".

    If you have any additional questions please contact Mr. Chris Calamita of my staff at (202) 366-2992.

    Sincerely,

    Stephen P. Wood
    Acting Chief Counsel

    Enclosure
    ref:209
    d.12/8/05