Interpretation ID: aiam4610

"Mr. R. Yamauchi Seat Belt Engineering Department Nippon Seiko K.K. 12 Kirihara-cho Fujisawa, JAPAN Dear Mr. Yamauchi: This responds to your letter asking for an interpretation of Standard No. 209, Seat Belt Assemblies (49 CFR /571.209). I regret the delay in responding. Your questions concerned a seat belt assembly that is designed with a dual mode retractor. The retractor for this system generally functions as an emergency locking retractor (ELR). However, the retractor can be converted to an automatic locking retractor (ALR) to facilitate securing a child restraint at that seating position. The retractor converts from an ELR to an ALR when the webbing is completely extended. The retractor converts back to an ELR when most of the webbing has been retracted. You posed the following questions. 1. Is this retractor considered an ELR? If so, is it required to comply with the performance requirements for ELR's, or is it required to comply with the performance requirements for both ELR's and ALR's? Response: Your letter did not provide sufficient information to allow us to answer this question. However, in a July 3, 1984 letter to Mr. Donald Schwentker, we explained the criteria we use to determine whether a dual mode retractor such as you described is considered an ELR or an ALR for the purposes of our safety standards. To briefly restate the criteria, section S4.1(g) of Standard No. 209 specifies adjustment requirements for all seat belt assemblies. We examine the functioning of the retractor during normal operation by occupants within the weights and dimensions set forth in S4.1(g)(3) of Standard No. 209. If 100 percent extension of the webbing is likely to occur during normal operation of the belt assembly by those occupants (thereby converting the retractor into an ALR), the retractor would be considered an ALR. If during normal operation of the belt assembly by the specified occupants the retractor would function exclusively as an ELR, the retractor would be considered an ELR. Using these criteria, the length of the webbing used in the belt assembly will ultimately determine whether a dual mode retractor would be considered an ELR. If the webbing is long enough that a 95th percentile adult male would not extend the webbing 100 percent during normal operations (including fastening and unfastening the belt or leaning forward to adjust the radio or other controls on the instrument panel), the retractor would operate exclusively as an ELR and would be treated as such for the purposes of our safety standards. If, on the other hand, normal operations by a 95th percentile adult male would result in 100 percent extension of the webbing, the retractor would be considered an ALR for the purposes of our standards. Your letter did not provide any information about the length of the webbing to be used in the belt assembly, so we cannot offer any opinion about whether the retractor for the belt assembly would be considered an ELR or an ALR. 2. You noted that section S5.2(k) of Standard No. 209 requires that ELRs be subjected to 45,000 additional cycles of webbing withdrawal and retraction between 50 and 100 percent extension. You stated if dual mode retractors were treated as ELRs, this requirement would present serious problems, since 100 percent webbing extension would convert the retractor to an ALR and the subsequent retraction to 50 percent extension would not convert the retractor back to an ELR. Hence, when the webbing returned to 50 percent extension after 100 percent extension, the retractor would be an ALR. In this mode, the retractor would lock the webbing at 50 percent extension and no further cycles would be possible. To avoid this problem, you asked if you could test the retractor by subjecting it to 45,000 additional cycles between 0 percent extension and 100 percent extension. You asserted that this testing should be permitted, because it is a more stringent test of the retractor. Response: This question may reflect a misunderstanding of the differing responsibilities imposed on a manufacturer that is certifying compliance with a safety standard and on the agency when it is testing for compliance with a safety standard. You, as a manufacturer, are not required to conduct testing before certifying that your belt assemblies comply with Standard No. 209. Instead, the National Traffic and Motor Vehicle Safety Act requires that you exercise 'due care' in making such certifications. It is up to the manufacturer in the first instance to determine what data, test results, computer simulations, engineering analyses, or other information it needs to enable it to certify that each of its products comply with all applicable safety standards. If a manufacturer chooses to conduct testing, the manufacturer is free to modify any or all parts of the test procedure specified in the standard, provided that the manufacturer can show that the results obtained using these modified test procedures are sufficient to satisfy the 'due care' standard. You have the responsibility in the first instance to decide whether the substitution of an alternative test is sufficient to establish due care in making certifications based on this modification of the standard. This determination involves assessing whether the results of the alternative test procedure are good predictors of the results of the test procedure specified in the standard. When the agency conducts its compliance testing, however, it is required to follow the compliance tests specified in the applicable standard. Thus, the agency would not substitute cycles between 0 and 100 percent extension for the cycles between 50 and 100 percent extension that are specified in Standard No. 209. If this retractor were treated as an ELR for purposes of Standard No. 209, applying the criteria set forth above in response to your first question, we would test the retractor solely as an ELR. To do this, we would disengage or disconnect the features that convert the retractor to an ALR at 100 percent webbing extension. The retractor would then be tested in accordance with the procedures set forth in S5.2(k) of Standard No. 209. I hope this information is helpful. Please let me know if you have any further questions or need additional information on this subject. Sincerely, Stephen P. Wood Acting Chief Counsel";