Interpretation ID: nht74-2.36

DATE: 05/06/74

FROM: AUTHOR UNAVAILABLE; Richard B. Dyson; NHTSA

TO: Questor Juvenile Products Company

TITLE: FMVSS INTERPRETATION

TEXT: This responds to your April 9, 1974, petition to substitute the proposed performance requirements for child harness testing under Standard No. 213, Child seating systems, for the performance requirements of Standard No. 209, Seat belt assemblies, to which Questor's Model 275 child harness is presently subject. As reasons for the substitution, you cite the inappropriateness of attachment hardware requirements (S4.3(c)) and the configuration of the test device (Figure 7) of Standard No. 209 as well as the desirability of testing to dynamic performance requirements which may become a part of Standard No. 213.

The Standard No. 213 dynamic test values which you recommend are only proposals at this time. Interested parties have not had a full opportunity to comment on them and the NHTSA has not, of course, had the opportunity to fully evaluate them. For these reasons your petition to substitute these new dynamic tests for the Standard No. 209 static tests is denied.

You state that testing of the Model 275 to the assembly performance requirements of Standard No. 209 (S4.4(c)) is complicated by the configuration of the test device for Type III harnesses, which is not suited to test a child harness such as the Questor No. 275 that utilizes the adult front lap belts and the rear adult lap belt or the package shelf as attachment points.

Paragraph S5.3(c)(2) of Standard No. 209 directs that in such a case "attachment shall be . . . in accordance with the [manufacturer's] installation instructions". As adherence to Model 275 installation instructions requires a front and rear adult belt installation (and in some cases a package shelf) the use of an actual vehicle bench seat in a passenger car would be an appropriate method to evaluate the assembly under S4.4(c) of Standard No. 209. Moreover, because the 12-inch extension requirement for an assembly tested under S4.4(c) is based on zero deflection of the test device, the actual vehicle seat should be modified to eliminate deflection.

The NHTSA has previously determined that the requirements of S4.3(c) of Standard No. 209 do not apply to bolts used to secure an adult upper torso restraint, other than the continuous loop type. Similarly, we interpret this provision not apply to the child harness upper torso restraint described in your letter. The bolts would be regulated with respect to strength only by the assembly performance requirements of S4.4(c).

Yours truly,

ATTACH.

April 9, 1974

Richard B. Dyson -- Office of Chief Counsel, National Highway Traffic Safety Administration Dear Mr. Dyson:

Questor Corporation has recently developed a novel child restraint harness that is to be marketed under the brand name "Infanseat Model 275 Child Restraint Harness." This restraint system has been under development for over two years to provide maximum dynamic performance at least possible cost to the consumer.

The Infanseat Model 275 Child Restraint Harness has closely approached the dynamic performance objectives proposed by the DOT to be effective September 1, 1975. When tested with a standard Sierra three-year-old child dummy, this restraint limited head excursion to 18.8 inches in a 30 mph frontal barrier impact test. Additional improvements in design have been made which will further reduce head excursion.

The unique design characteristics of this harness, which provide exceptional dynamic performance, also present difficulties in determining its compliance with FMVSS 209 for Type 3 seat belt assemblies. These problems were discussed with Messrs. R. Jasinski, J. Gilkey, T. Herlihy, and M. Peskoe during a personal visit to Washington on April 4. Mr. Jasinski also reviewed the situation in a phone conversation with Mr. R. Hitchcock. It was suggested after these conversations that this letter be written to you, outlining the areas of concern relative to FMVSS 209.

The design of Infanseat Model 275 Child Restraint Harness departs radically from child harnesses commercially available to date. Current harnesses require mounting to the floor of the automobile to restrain the child and vehicle seat back from movement during impact or load. Inasmuch as this floor anchorage could inadvertently be used by the present automobile owner or subsequent owners for an adult lap belt attachment point, it is understandable that FMVSS 209 would require the strength of this anchorage to be no less than 5,000 pounds, paragraph S4.3 (c) (1).

It is further recognized that currently available child harnesses loop over the adult backrest of automobiles, prior to being themselves anchored to the vehicle floor, and thus largely rely upon the strength of the automobile backrest to reduce movement of the child in an accident situation and/or also restrain the backrest. The assembly performance criteria of FMVSS 209 paragraphs S5.3 (c) (1) through (4) provide some degree of simulating this installation, and yet the force requirement that the complete assembly is required to withstand is 2,000 pounds, 100 per cent greater than the force requirements of FMVSS 213.

The Model 275 Child Harness is shown in accompanying Figures 1 and 2. The significant differences in its installation when compared with existing harnesses are readily apparent.

Firstly, an adult lap belt is used to position the lower portion of the child's harness both laterally and forwardly. Secondly, a back strap, or upper tie-down, connects the child harness at the shoulder strap area to either a rear seat adult lap belt for a front seat installation (Figure 1) in an automobile or to a supplementary anchor installed in the metal portion of the panel between the seat back and the rear window for rear seat installation (Figure 2). Neither the front nor rear seat installations require changes or additions to anchorages at the vehicle floor.

The viability of the upper tie-down attachment has been dynamically demonstrated by a well-known child seating restraint system that not only must restrain the child but also the child seating system itself. The upper tie-down strap most nearly approximates the function of an adult shoulder strap; that is, it keeps the upper torso from pivoting forward in a frontal impact. FMVSS 209 does not specify minimum force requirements for either Type 2, Type 2a, or Type 3 upper torso restraint attachment hardware.

It is suggested, therefore, that the requirements within FMVSS 209 for attachment hardware are neither clear nor appropriate for the Infanseat harness. In addition, the test method for assembly performance does not provide for the recommended installation of this product.

While attempts could be made to modify the simulated seat back shown in Figure 7 of FMVSS 209 to provide for the installation of the Infanseat harness, it is felt that any modification will not adequately reporduce the distribution of forces encountered in real-world situations. Also, any approved simulated static load test of a complete assembly at this time is not felt to be appropriate with dynamic testing of child harnesses soon to be required.

It is respectfully suggested that rather than subject the DOT to possible adverse public criticism by requesting another static test to determine the adequacy of the complete Infanseat harness assembly, it be excluded from the attachment hardware and complete assembly requirements of FMVSS 209. In lieu of these requirements, the Infanseat harness should be required to prevent head excursion of a Sierra three-year-old test device beyond 18 inches in a simulated 30 mph frontal impact test. The Infanseat harness would thus be required to meet the DOT's proposed dynamic performance requirements for child restraints.

Data substantiating the dynamic performance of the Infanseat harness has been independently verified by tests conducted for Consumers Union on prototype harnesses. These tests were not published by CU because the harnesses were not available commercially when their magazine went to press. Additional tests have been conducted to determine the suitability of various materials, installations, and test devices. Significant improvements to the harness are expected to be made, such that it appears likely in the very near future to provide dynamic protection for six-year-old children within the proposed excursion limits desired by the DOT.

As important as the Infanseat harness's dynamic performance is its expected retail selling price. The DOT and child restraint manufacturers are equally concerned that children's restraint devices be affordable by the largest possible segment of the public. It is recognized that the purchase and, therefore, the eventual use of children's restraints are directly related to their cost. The Infanseat harness is expected to be marketed at one-half to one-third of the price of existing restraint systems.

Thank you for your attention to this request for revised interim requirements that would be applicable to the Infanseat harness, and your early response shall be greatly appreciated. It is understood that this product would automatically be required to comply with the proposed revisions to FMVSS 213 when they become effective.

Yours very truly,

QUESTOR JUVENILE PRODUCTS COMPANY;

J. P. Koziatek, P.E. #E-36338 -- Director, Technical Services

Attachments

cc: R. Hitchcock; T. W. Herlihy; M. P. Peskoe; J. C. Gilkey; R. Jasinski

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