Early Development Co.
6135 Park South Dr., Suite 420
Charlotte, NC 28210
Dear Mr. Cathcart:
This responds to your February 5, 1996 letter concerning Federal Motor Vehicle Safety Standard No. 213, AChild Restraint Systems.@ I apologize for the delay in responding.
You explain in your letter that your company manufactures child restraints with emergency locking retractors (ELRs) which automatically adjust the shoulder straps to fit the child occupant. You are concerned about a provision in Standard 213 which you call the Asnug fit test procedure,@ that you believe calls for (quoting from your letter):
1. The dummy to be placed in the child safety seat and the child safety seat=s restraint fastened according to the manufacturer=s instructions. The position and fit of the belts on the dummy=s shoulders is then visually inspected to see that the shoulder straps are correctly positioned without gaps.
2. A probe is placed between the shoulder strap and the dummy=s shoulder. The shoulder strap is then pulled upward with two pounds of pressure, and again the straps are visually inspected to see that they lay properly in place and that no gaps greater than 1/4 inch exist.
You state that A[t]he application of two pounds of pressure is not enough to engage the ELR.@
You indicate that the National Highway Traffic Safety Administration=s (NHTSA=s) Office of Safety Assurance (NSA) has informed you that Athe second phase of the test is not applicable with ELR units. . . .@ That is, in your words, AIf the belts fit snugly on the child dummy=s shoulders, ELR seats have been deemed to pass the >snug fit= requirement. The seats are then move [sic] on to be dynamically tested.@ You agree that this is the correct position and request our concurrence on the matter.
We generally concur that the procedure of the second phase, applying two pounds of force using a probe, would not Aapply@ to an ELR system. However, several matters should be clarified.
There is a requirement in Standard 213 that each child restraint belt that is designed to restrain a child shall be adjustable to Asnugly fit@ any child whose height and weight are within the ranges recommended by the manufacturer for the restraint (S22.214.171.124). A visual inspection by NSA checks that this requirement is met. However, the Asnug fit test procedure@ you ask about relates to a test condition set forth in S6.1.2(e) for the sled test. This section specifies that, prior to sled testing, the belts on a child restraint shall be adjusted, while applying a two pound force using a probe, so that there is 7 millimeters (1/4 inch) of slack.
We concur that this specification of test conditions does not apply to ELR systems. At the time the test condition was adopted, all belts on child restraint systems then on the market were manually adjustable. Hence, they could be adjusted to introduce any amount of slack desired. In general, the more slack there is, the more severe the test, which may result in greater dummy excursions and a greater likelihood that a restraint may fail the performance requirements of Standard 213. To ensure that child restraints would be tested under identical conditions, S126.96.36.199 was added to Standard 213 specifying the precise amount of slack that should be present.
In a system with ELRs, the retractors remove the slack from the belts on their own. Thus, there is no need for the Asecond phase@ of the procedure to adjust the amount of slack in the belts. Moreover, since the ELRs will not be activated on application of the two pound force used in the second phase, applying the force would not serve to measure slack in the belts, but would simply spool out the webbing. Accordingly, NHTSA will not use the procedure with systems such as yours.
I hope this information is helpful. If you have any other questions, please contact Deirdre Fujita of my staff at this address or by telephone at (202) 366- 2992.
Samuel J. Dubbin Chief Counsel
The language of S6.1.2(e) was formerly set forth in paragraph S188.8.131.52. The text of Standard 213's test procedure was reorganized in a final rule published July 6, 1995 (60 FR 35126), effective January 3, 1996. While S6.1.2(e) uses metric units, we use English units in this letter because your letter did so.