The Booster Seat Company Ltd.
P.O. Box 15-573, New Lynn, Auckland
Dear Mr. Lord:
This responds to your letter asking about S5.5.1(a) in Federal Motor Vehicle Safety Standard No. 213, AChild Restraint Systems.@ I apologize for the delay in responding.
As discussed below, it is our opinion, based on the information in your letter, that your child restraint would not meet S5.1.1(a).
Background You state in your letter that your company has developed a child restraint system which conforms to an Australian child seat standard. A U.S. company wishes to manufacture and sell the child seat in the United States. You have had the child seat dynamically tested in the U.S., and believe that the seat achieved Avery favorable results@ with regard to the injury criteria of Standard 213. However, S5.5.1(a) of the standard was a problem.
Section S5.1.1 sets forth requirements for child restraint system integrity. Paragraph (a) of that section states that when dynamically tested, each child restraint shall:
Exhibit no complete separation of any load bearing structural element and no partial separation exposing either surfaces with a radius of less than 1/4 inch or surfaces with protrusions greater than 3/8 inch above the immediate adjacent surrounding contactable surface of any structural element of the system . . . .
Your child seat, a belt-positioning seat under S4 of Standard 213, consists of a high density polystyrene (commonly called
Astyrofoam@) platform, covered by a foam seat cover. The platform raises a child occupant approximately four to five inches to better fit a vehicle=s Type II belt system. The styrofoam platform also has arm rests formed into it.
The child seat cracked during the dynamic test of Standard 213. You sent us a child seat showing the cracks. However, you believe the cracking of the seat should not be considered to be a violation of S5.1.1(a) because, in your opinion, it does not pose a safety problem:
Clearly cracking/splitting on blow molded plastic possesses a serious safety issue with the possibility of pinching, cutting, or stabbing the child. We are confident that polystyrene possess [sic] no such problem. By nature, all cracked edges are soft. In addition, the product is sold with a 3/8" (10mm) foam seat cover.
After reviewing your submissions and other information, our answer is that the child seat would not meet S5.1.1(a). Because the cracks occurred in a load bearing structural element of the child seat, S5.1.1(a) applies. Each crack is a Apartial separation exposing . . . surfaces with a radius of less than 1/4 inch . . . ,@ which is prohibited by S5.1.1(a).
This interpretation limits a previous agency interpretation of S5.1.1(a). In NHTSA=s July 8, 1988 letter to Mr. Donald Friedman of Liability Research, Inc. (copy enclosed), the agency addressed whether edges exposed by the tearing of a restraint that was made of woodfiber violated S5.1.1(a), when the edges exposed by the tearing were not lacerating (due to the composition of the material) and not likely to come into contact with the infant. NHTSA said that S5.1.1(a) did not prohibit the tearing because:
. . . In the preamble of [the rulemaking document proposing the requirement], we stated that our objectives in promulgating the system integrity requirements were to prevent a child=s excessive excursion or ejection from the system, and to ensure that the system does not fracture or separate in such a way as to harm the child. (43 FR 21470, 21473.) (Emphasis in text.)
In the Friedman letter, NHTSA focused on the highlighted text, stating that any partial separation resulting from the dynamic test Amust not expose surfaces with sharp edges that may contact the child.@ The agency did not examine the effect of partial separations on the structural integrity of the system. Nevertheless, the agency acknowledged that, @In promulgating S5.1.1(a), the agency intended to minimize dangers resulting from failures in the structural integrity of the system, rather than failures in the materials.@
Your child restraint is formed from a single piece of styrofoam; there is no reinforcement of any kind. As you note, due to the material comprising the restraint, the child restraint Ais inclined to crack.@ With your child restraint, a failure in the material results in a failure in the structural integrity of the system. While the edges formed by the partial separations you identified might not form Asharp@ edges, the partial separations are an indication that the structural integrity of the restraint has not been maintained. Thus, we conclude that the restraint would not meet the requirements of S5.1.1(a).
I hope this answers your inquiry. If you have further questions, please do not hesitate to contact Deirdre Fujita of my staff at this address or by telephone at (202) 366-2992.
Samuel J. Dubbin Chief Counsel