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Interpretation ID: 21492volvotension



    William Shapiro, P.E.
    Director, Regulatory Compliance and Environmental Affairs
    Volvo Cars of North America, Inc.
    Volvo Drive
    Rockleigh, NJ 07647-0913


    Dear Mr. Shapiro:

    This responds to your letter asking about a certain aspect of the dynamic test procedure of Federal Motor Vehicle Safety Standard (FMVSS) No. 213, Child Restraint Systems, as applied to a new add-on rear-facing child restraint system that Volvo has developed. Your question relates to a movable surface, a "tension bracket," on the child restraint system that a consumer installing the child restraint would adjust. The tension bracket would increase the tension of the vehicle belt system that attaches the child restraint to the vehicle seat. You ask whether we would deploy the tension bracket in our compliance test of Standard No. 213. Our answer is no.

    Background
    You explain that the child restraint system ("CRS") is designed in both an infant-only configuration (for children with a mass of up to 10 kilograms (kg)), and a "toddler" configuration (children in the range of 9 to 18 kg). You state that both configurations use a base, or frame, that attaches to the vehicle seat by way of the vehicle belt system and by components that attach to the lower bars of a child restraint anchorage system (see FMVSS No. 225, 49 CFR 571.225).

    Your inquiry relates to attaching the child restraint system by way of the vehicle belt system. Volvo designed a tension bracket for this means of attachment, described by you as: "an inverted "U"-shaped surface, attached near the edge of the CRS base or CRS frame (the edge of the CRS which is closest to the vehicle's seat bight)." When the tension bracket is deployed, it "increases tension on the vehicle's belt system, enhancing the coupling of the CRS to the vehicle seat...."

    Section 6.1.2(d)(ii) of Standard No. 213 specifies that, when a child restraint is tested on the standard seat assembly when attached by a Type I (lap belt), the belt is tightened to a tension of not less than 53.5 Newtons (N) and not more than 67 N. Volvo believes that the dynamic test should be conducted by "first, routing the standard vehicle lap belt through the CRS belt path/guide, second, adjusting the belt tension to be in the range of 53.5-67 N, and then third, pushing the tension bracket ("U"-shaped surface) against the vehicle seat back by pushing the handle at the top of the tension bracket and the padded top crossbar of the CRS frame apart." Deploying the tension bracket in the sequence will increase the belt tension above 67 N.

    You believe that the dynamic test procedure (S6.1.2) of Standard No. 213 permits the deployment of the tension bracket and the resultant increase in belt tension (above 67 N) because S6.1.2 specifies that the add-on child restraint system is installed at the center seating position of the seat assembly "in accordance with the manufacturer's instructions provided with the system." You state that your instructions tell the consumer to (a) "tighten the lap belt fully" while pressing the base into the seat cushion, then (b) deploy the tension bracket. You therefore believe that the dynamic test should be conducted with the tension bracket deployed, since deploying it would be in accordance with your instructions.

    Discussion
    We do not agree that, for purposes of conducting the dynamic tests in Standard No. 213, the tension bracket should be deployed after the lap belt has been adjusted to 53.5 to 67 N.

    The dynamic test procedures of Standard No. 213 are carefully controlled to ensure that all child restraints are tested in the same manner, under identical conditions. Section 6.1.2(d)(ii) of Standard No. 213 specifies the amount of tension that must be on the lap belt (not less than 53.5 N to not more than 67 N) to control the means of attaching each child restraint, thereby reducing variability, and to better assess the performance of the restraint. Under the test procedures of the standard, the tension of the lap belt is checked and controlled immediately before the dynamic test. (See S6.1.2(d)(ii) and S6.1.2(e).) Contrary to your suggestion, we do not subsequently adjust the child restraint to make sure that various features of the restraint that may have been added by the manufacturer are deployed.

    Further, specifying the amount of tension that is in the lap belt helps ensure that all child restraints can provide a minimum level of safety when attached in a standardized manner. In our view, no child restraint can be tested with more than the specified 67 N of tension, since that would make the test less stringent. We note that the child restraint requires action on the part of the consumer to increase the belt tension. It does not do so automatically. If the tension adjustment in the seat operated automatically, such that it was impossible to install the seat at a tension below 67 N, we would test at the higher tension.

    With your child restraint system, the benefits from the increased tension of the vehicle belt will not be realized by consumers who neglect to deploy the tension bracket or who do so incorrectly. The possibility of the tension bracket not being used is not insignificant, since child restraints do not generally use a tension bracket. The attachment of child restraints to vehicle seats is intended to be standardized. Thus, child restraints must meet the minimum performance requirements of Standard No. 213 regardless of whether a tension bracket is deployed, to guard against a degradation of safety in cases where the bracket is misused.

    Accordingly, we conclude that child restraints must meet the minimum performance requirements of Standard No. 213 when the lap belt has a tension of not more than 67 N. We realize that your feature can tension a vehicle belt further and that the removal of slack in the belt system is generally beneficial to child restraint performance. However, our conclusion ensures that child restraints provide a minimum level of safety even when features that are supplemental to the standard means of attaching a child restraint are not used as intended.

    If you have any further questions, please contact Deirdre Fujita of my staff at (202) 366-2992.

    Sincerely,

    Frank Seales, Jr.
    Chief Counsel

    ref:213
    d.10/17/00