Mr. Daniel J. Selke
Manager, Safety Engineering
Mercedes-Benz of North America, Inc.
One Mercedes Drive
P.O. Box 350
Montvale, NJ 07645-0350

Dear Mr. Selke:

This responds to your letter to the National Highway Traffic Safety Administration (NHTSA) asking about the test requirements in Federal Motor Vehicle Safety Standard No. 213, "Child Restraint Systems," for a child restraint system you plan to sell. You believe that the system is a "built-in" child restraint system under Standard 213 and ask for confirmation that the restraint will not be tested in "misuse" configurations, i.e., installed on the testing apparatus in ways contrary to Mercedes-Benz's instructions for using the restraint. As explained below, we have carefully considered your suggested interpretation and regret that we cannot confirm it.

You describe the restraint as follows:

The system is composed of two parts; an integrated booster cushion and an add-on impact shield. The booster cushion is operated by a push-button. When activated, a portion of the rear seat of a vehicle equipped with the system raises to form the booster cushion. . . .[Daimler-Benz AG's (DBAG's)] integrated child restraint system is a progressive system designed for use with children as they grow older. The impact shield is designed for use in conjunction with the booster seat for children who weigh 9 to 18 kg (20 to 40 lbs.). The impact shield is secured directly in front of the child by the lap and shoulder belt with the "legs" of the shield stabilized by being placed on both sides of the booster cushion. Without the presence of the booster cushion, the "legs" of the impact shield would collapse making use of the shield alone unrealistic. The design of the impact shield acts to secure the child's torso and to keep the child's legs fixed. Children who weigh 18 to 36 kg. (40 to 80 lbs.) only need the booster seat and standard lap and shoulder belt to be properly secured. Children who weigh more than 36 kg (80 lbs.) may use the conventional lap and shoulder belts.

For convenience, we have depicted these recommended weight ranges and restraint configurations in the following table:


If a child in this weight range is to be restrained then restrain the child by using the--
20 to 40 lb. Booster cushion, impact shield, and lap/shoulder belts
40 to 80 lb. Booster cushion and lap/shoulder belts
Over 80 lb. Lap/shoulder belt

Your specific questions concern how NHTSA would test the restraint. You want us to confirm that when the restraint is tested in the configuration intended for children under 40 lb., the agency would test the system using both the booster and the shield with the vehicle's lap and shoulder belt. You also ask us to confirm that when the restraint is tested in the configuration intended for children greater than 40 lb., the booster would be used with the vehicle's lap and shoulder belt. You would like us to concur that "At no time, would testing of the system be required that involved use of the shield without the booster."

We agree with some of your statements but do not agree with others. We agree that the shield would not be tested without the booster. Standard 213 defines a "child restraint system" as "any device except Type I or Type II seat belts, designed for use in a motor vehicle or aircraft to restrain, seat, or position children who weigh 50 pounds or less." An impact shield is designed "to restrain. . . children." The standard also defines an "add-on" child restraint system as "any portable child restraint system." A portable impact shield that is sold to consumers without any other accompanying parts would be an add-on child restraint system and, obviously, would be tested to Standard 213's requirements without any other part. Your shield, however, is merely a component of a child restraint system and is not intended to be used separately from the other parts of the restraint system. The shield cannot even support itself on its "legs" without the booster cushion. Because of these factors, we do not consider your impact shield to be an add-on child restraint system. The shield itself would not be tested to the requirements of Standard 213 without the booster.

However, there is a question of whether your restraint system (booster cushion with impact shield) is a "built-in child restraint system" under Standard 213 (S4). Configured in the mode used to restrain children under 40 lb., the restraint does not meet the standard's definition of a "built-in child restraint system."

The standard defines "built-in child restraint system" as "a child restraint system that is designed to be an integral part of and permanently installed in a motor vehicle." (Emphasis added.) NHTSA has used the term "integral" in the context of Standard 213 to mean "formed as a unit with another part." See, e.g., April 29, 1980 letter to Mr. Koziatek (copy enclosed). The add-on impact shield would not be formed as a unit with the motor vehicle. Also, the add-on shield would not be "permanently installed" in the vehicle. Because of these factors, we would not consider the add-on shield to be part of the built-in child restraint system. Accordingly, we would not use the shield when testing the restraint in Standard 213 compliance tests.

This means that the booster would have to meet Standard 213's requirements when configured so as to consist of the cushion alone with the lap and shoulder belts, without the shield, and when tested with each of the appropriate test dummies specified in the standard. The standard specifies that child restraints recommended for children weighing 20 to 40 lb. are tested with a dummy representing a 3-year-old child. Because the add-on shield is not part of the built-in system, it would not be used in the compliance test using the 3-year-old dummy, notwithstanding any instructions you might provide to consumers to use the shield. Add-on, nonpermanent components can be lost or misplaced and may not be accessible when the restraint has to be used.

Standard 213 does not prohibit you from voluntarily providing add-on pieces to possibly improve the performance of your built-in restraint. However, as stated in the preceding paragraph, the restraint must provide a minimum level of safety and meet Standard 213's requirements without use of the add-on components, to ensure that the restraint will provide adequate protection in the event the add-on components are not used. Of course, if Mercedes-Benz redesigned this seat to assure that the shield was "integral" and "permanently installed," these considerations would not apply.

With respect to the restraint's configuration for older children, Standard 213 also specifies that a test dummy representing a 6-year-old child is used to test a child restraint that is recommended for children weighing 40 or more lb. Accordingly, we would also use the 6-year-old dummy in compliance tests to test the booster cushion and lap and shoulder belts. We agree with you that when the booster is tested in the configuration intended for children greater than 40 lb., the booster would be used with the vehicle's lap and shoulder belt, without the shield.

There is another matter we would like to address, concerning your labeling of the restraint for children weighing as little as 20 lb. You should note that S5.5.5(f) of Standard 213 prohibits manufacturers from recommending booster seats for children less than 13.6 kilograms (30 lb.). This prohibition is based on test data that showed that the 20 lb. dummy (representing a 9-month-old child) was consistently ejected from booster seats in 30 mile per hour dynamic tests. (See final rule adding the prohibition to Standard 213, 59 Fed. Reg. 37167, July 21, 1994.) NHTSA believes children weighing approximately 20 to 30 lb. need a restraining system that provides a higher degree of upper torso and crotch restraint, such as that provided by convertible or toddler restraints, than that provided by a booster seat. Accordingly, the DBAG booster seat must not be recommended for children weighing less than 30 lb.

We would like to take this opportunity to make one last point before closing. In arguing that the DBAG booster seat should be tested only in accordance with your instructions for using the restraint, you state that Standard 213 "was not designed to sanction improper use or misuse of any child restraint system...." Standard 213 is intended to address, among other things, the problem of misuse of child restraints. It does so by requiring restraints that have features that are likely to be misused to meet performance requirements when installed on the test seat assembly in the "misuse" mode. For example, because NHTSA determined that parents were not attaching the top tethers of child restraints when installing the restraints in their vehicles, Standard 213 was amended to require restraints that have tether straps to meet the standard's requirements with the tether unattached. (See S6.1.2(a)(1), requiring restraints to be secured using only a lap belt and without a tether.) Standard 213 also addresses misuse by standardizing certain aspects of child restraints, such as the manner of installation, to reduce the chance of confusion and incorrect use resulting from such confusion. We believe that the likelihood that parents will misuse a built-in system is reduced when all the components needed to restrain the child are built into the child restraint system.

I hope this information is helpful. Please contact Deirdre Fujita of my staff at (202) 366-2992 if you have other questions.

Frank Seales, Jr.
Chief Counsel