Interpretation ID: 571.213--Weber--8 25 1998

Ms. Kathleen Weber

Project Director

University of Michigan

Child Passenger Protection Research Program

2901 Baxter Rd.

Ann Arbor, MI 48109-2150

Dear Ms. Weber:

This responds to your letter to the National Highway Traffic Safety Administration (NHTSA) asking us to clarify the meaning of S5.1.3.2 of Federal Motor Vehicle Safety Standard

No. 213, Child Restraint Systems.

Section S5.1.3.2 states:

In the case of each rear-facing child restraint system, all portions of the test dummys torso shall be retained within the system and neither of the target points on either side of the dummys head and on the transverse axis passing through the center of mass of the dummys head and perpendicular to the heads midsagittal plane, shall pass through the transverse orthogonal planes whose intersection contains the forward-most and top-most points on the child restraint system surfaces (illustrated in Figure 1C).  (Emphasis added.)

You ask whether the underlined phrase means that both of the planes must be passed for there to be a failure, or whether passing a single plane would be sufficient to constitute a failure.  For the reasons set out below, we construe this phrase to mean that passing through any single plane constitutes a failure to comply with the standard.

In reviewing the language of S5.1.3.2, we recognize that the plural planes could be read to refer to both or either of the planes.  Fortunately, we believe this possible ambiguity can be resolved using a common sense approach.  If S5.1.3.2 were read to specify that both of the planes must be passed for there to be a failure, there would be no failure if only the upper limit illustrated in Figure 1C (the plane containing the top-most point on the child restraint system surface) were passed.  That result would render the upper limit plane meaningless.  In contrast, if S5.1.3.2 is construed to mean that passing either of the planes could constitute a failure, each of the planes is meaningful in determining the excursion limits.  For example, it may be possible for the test dummy to not ramp up and exceed the upper limit depicted in Figure 1C, yet the dummys head could rotate sideways in such a way that it could pass through the plane that designates the forward limit, especially with restraints that have little or no side supports for the childs head.

I hope this answers your question.  If we can be of further assistance, please contact Deirdre Fujita of my staff at (202) 366-2992.

Sincerely,

Frank Seales, Jr.                                                                  

Chief Counsel

Dated: 8/25/98

Ref: Standard No. 213