Interpretation ID: aiam4584
Automotive Safety Office Environmental and Safety Engineering Staff Ford Motor Company The American Road Dearborn
MI 48121;
"Dear Mr. Munson: This responds to your letter in which you suggeste that there are some apparently inconsistent provisions in Standard Nos. 208, Occupant Crash Protection (49 CFR /571.208) and 209, Seat Belt Assemblies (49 CFR /571.209). With respect to manual belt systems installed at front outboard seating positions in a vehicle which is certified as complying with the dynamic testing requirements in Standard No. 208, you asked whether those belt systems may be equipped with load limiters, such that the belt assembly does not comply with the elongation requirements in Standard No. 209. For the reasons explained below, the answer is no. Your letter suggested that Standard No. 209 contains two different provisions that yield inconsistent answers to this question. On the one hand, section S4.5(b) of Standard No. 209 reads as follows: 'A Type 1 or Type 2 seat belt assembly that includes a load limiter and that does not comply with the elongation requirements of this standard may be installed in motor vehicles only in conjunction with an automatic restraint system as part of a total occupant restraint system.' Section S3 of Standard No. 209 defines a 'load limiter' as 'a seat belt assembly component or feature that controls tension on the seat belt to modulate the forces that are imparted to occupants restrained by the belt assembly during a crash.' These provisions of Standard No. 209 seemingly preclude the use of a load limiter on manual belts, if the load limiter results in the belt assembly not complying with those elongation requirements, unless the seating position in which such manual belts is also equipped with an automatic restraint system. Accordingly, dynamically tested manual belts installed at seating positions that do not include any automatic restraint system could not be equipped with a load limiter, if the load limiter resulted in the belt no longer complying with the elongation requirements. On the other hand, section S4.6 of Standard No. 209 exempts dynamically tested manual belts from the elongation requirements of the standard, as well as the webbing width and strength requirements. This exemption applies without respect to whether the dynamically tested manual belt is equipped with a load limiter. Ford suggests that this provision means that a manual belt installed at a front outboard seating position could be equipped with a load limiter, even if the load limiter resulted in the belt assembly not complying with the elongation requirements, provided that the vehicle in which the belt was installed was certified as complying with the dynamic testing requirements in Standard No. 208. In your letter, you said that it was Ford's interpretation that the requirements of S4.6 of Standard No. 209 were meant to limit the prohibition in S4.5 of Standard No. 209, by permitting the use of load limiters that result in the belt assembly no longer complying with the elongation limits on either automatic belts or dynamically-tested manual belts. You suggested that the reasoning that caused the agency to limit the use of load limiters that result in the belt not complying with the elongation requirements to automatic belts only, in section S4.5, does not apply to dynamically tested manual belts. You quoted the following language from the notice that established S4.5: T here are currently no dynamic performance requirements or injury criteria for manual belt systems used alone. There are no requirements to ensure that a load-limiting belt system would protect vehicle occupants from impacting the steering wheel, instrument panel, and windshield, which would be very likely if the belts elongated beyond the limits specified in Standard No. 209. Therefore, the elongation requirements are necessary to ensure that manual belts used as the sole restraint system will adequately restrain vehicle occupants. 46 FR 2618, at 2619, January 12, 1981. You noted that this reasoning is now outmoded for some manual belts, because dynamic testing requirements have been established for certain manual belts. In fact, you asserted that the agency has expressly recognized this by exempting dynamically-tested manual belts from the elongation requirements of Standard No. 209. Accordingly, you believe that S4.5 of Standard No. 209 should be interpreted to permit the use of load limiters that cause the belt to no longer comply with the elongation requirements on either automatic belts or dynamically tested manual belts. As further support for this position, your letter suggested that the agency's notices establishing dynamic testing requirements for manual belt systems show an intent to treat dynamically-tested manual belts in the same way as automatic belts for the purposes of Standard No. 209. You referred to our rule adopting dynamic testing requirements for manual safety belts in front outboard seating positions of passenger cars (51 FR 9800, March 21, 1986), the rule extending dynamic testing requirements to manual belts installed at front outboard seating positions of light trucks and multipurpose passenger vehicles (52 FR 44898, November 23, 1987), and the denial of petitions for reconsideration asking the agency to rescind the exemption of automatic belts and dynamically tested manual belts from the webbing width, strength, and elongation requirements of Standard No. 209 (53 FR 5579, February 25, 1988). Because of the agency's consistent expression in these three notices of its intent to treat dynamically tested manual belts in the same way automatic belts are treated under Standard No. 209, you believe that the reference in S4.5(b) of Standard No. 209 permitting load limiters on belts used 'in conjunction with an automatic restraint system' should be interpreted to mean load limiters may be installed on belts used in conjunction with an automatic or dynamically tested manual restraint system. I do not concur with your suggested interpretation. I believe that sections S4.5 and S4.6 yield inconsistent answers to your question. Section S4.6(a) exempts manual belts from elongation requirements. However, it does not speak to the consequence of installing a load limiter on a belt that does not comply with those requirements. Section S4.5(b) does speak to this issue. It says that such a belt may be used only in conjunction with an automatic restraint. To be more specific, section S4.5 expressly provides that a belt assembly that 'includes a load limiter and that does not comply with the elongation requirements of this standard may be installed in a motor vehicle only in conjunction with an automatic restraint system as part of a total occupant restraint system.' I appreciate that the discussion you quoted from the 1981 notice is consistent with your argument that load limiters should be permitted on any dynamically-tested manual belt. Nevertheless, regardless of whether you believe that NHTSA intended to make or should have made such a change when in adopting dynamic testing requirements for manual belts, it is not possible to interpret the term 'automatic restraint system,' as used in S4.5, to mean 'automatic restraint system or dynamically tested manual restraint system.' An interpretation cannot add or delete requirements that are not contained in the language of the standard itself. When the agency promulgates a safety standard specifying performance requirements for vehicles or items of equipment to accomplish a particular safety purpose, that safety standard sets forth all the requirements with which the vehicles or equipment must comply. If the requirements in the safety standard do not fully address or ensure the implementation of some aspect of the underlying safety purpose, that aspect is not part of the standard. Since an interpretation cannot amend the language of a safety standard, the agency's only recourse in these situations is to undertake rulemaking to amend the language of the standard. You asked that we treat your request for an interpretation as a petition for rulemaking if, as we have done, we concluded that your suggested interpretation was incorrect. We will notify you of our response to this petition as soon as we complete our review of it. Sincerely, Erika Z. Jones Chief Counsel";