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Interpretation ID: NCC02000890IIogm

    Ms. Sonja Polt
    Concept Technologie GmbH
    Fischeraustrasse 13
    A-8051 Graz Austria


    Dear Ms. Polt:

    This is in response to several questions contained in your electronic mail message to the National Highway Traffic Safety Administrations Office of Chief Counsel regarding test procedures under the head impact protection provisions contained in Standard No. 201, Occupant protection in interior impact. Your electronic mail message states that your company is concerned about which approach and "roll" angles should be used when testing a target located on a seat belt anchorage. You note that the anchorage in question is located on the B-pillar of a vehicle your company is testing. As shown in a photograph embedded in your electronic mail message, this seat belt anchorage projects above the surface of the B-pillar.

    Specifically, you note that Standard No. 201 specifies different vertical and horizontal approach angles for seat belt anchorage targets and targets located on a B-pillar. As the target in question is a seat belt anchorage located on a B-pillar, you ask whether the approach angles for a seat belt anchorage or for a B-pillar target apply. You also ask if the "roll" or offset angle should be the 5 degree angle used for all targets except those on the B and other pillars or the 10 degree angle used for B and other pillars.

    Standard No. 201 establishes performance requirements for certain areas of vehicle interiors but does not require that all areas of the upper interior of a vehicle be subjected to compliance testing. Instead, the standard sets forth a number of discrete target areas that must be impacted by a test headform known as the Free Motion Headform (FMH). According to the standard, if a seat belt anchorage is located on the B-pillar, the target area known as BP2 is located on that anchorage. The performance requirements for the target areas are intended to reduce the risk of occupant head injury by ensuring that vehicle interiors have certain impact characteristics. All of the target areas may be impacted by the FMH provided that the FMH is directed at the target within a certain range of angles. These angles are referred to in Standard No. 201 as approach angles. If an approach angle for a particular target is within the range of permissible approach angles, that angle may be used in testing a target area.

    S8.13.4 of the standard specifies a range of permissible horizontal and vertical approach angles that constrain the direction of the FMH when approaching particular types of targets. The approach angle limits are specified in Table 1 of the standard. That table separately lists, among other targets, the left B-pillar, right B-pillar, and seat belt anchorages. However, the table does not indicate what angles are to be used when a target is on a seat belt anchorage that is also located on a pillar.

    We partially addressed your question in an October 15, 2002, letter to Mr. Takashi Yoshie of the Toyota Technical Center (copy enclosed). In response to Mr. Yoshies inquiry regarding the proper offset angle to be used when testing a seat belt anchorage on the B-pillar, we indicated that in those instances where the anchorage projects above the surface of the B-pillar, the appropriate offset angle is five degrees. However, we indicated that if the anchorage does not project above the surface of the B-pillar, the maximum offset of the vertical approach angle is ten degrees. As the photograph embedded in your message shows target BP-2 located on a seat belt anchorage that projects above the surface of the B-pillar, the appropriate angles would be those used for seat belt anchorages.

    As we explained in our letter to Mr. Yoshie, the offset angles set forth in S8.13.4.2(b) were chosen to delay chin contact with the vehicle to allow appropriate HIC calculations. Ten degrees of downward rotation was determined to be an appropriate amount for determining the maximum vertical approach angle for B-pillar and other pillar targets. Five degrees of downward rotation was determined to be the appropriate amount for seat belt anchorage targets. In the case of seat belt anchorages mounted above the surface of the B-pillar, a ten degree offset would be unnecessary. Where the anchorage design results in BP2 being on or below the surface of the B-pillar, ten degrees would be appropriate to prevent early chin contact.

    Once the appropriate offset angle is applied and the maximum vertical angle is established, one must determine which one of the range of horizontal and vertical approach angle limits listed in Table 1 applies. We note that in establishing the range of horizontal and vertical approach angle limits for seat belt anchorages, the agency indicated that seat belt anchorages could be approached at any horizontal angle. This choice of an unlimited range of horizontal angles was based on the agencys expectation that seat belt anchorages would most likely be protruding into the vehicle and could be contacted at any horizontal angle. Similarly, the agencys choice in setting vertical approach angle limits for seat belt anchorages, zero to fifty degrees, also reflects our expectation that seat belt anchorages would protrude into the vehicle. Unlike the limits set for pillar targets, which have lower limits adjusted to delay chin contact, the vertical approach angle limits for seat belt anchorages have a lower limit of zero.

    Because we set seat belt anchorage approach angle limits under the expectation that these anchorages would protrude into the vehicle interior, where a target is located on a seat belt anchorage that is also on a pillar, the seat belt anchorage approach angles limits apply in those instances where the anchorage is located above the surface of a pillar. Where the anchorage is located on or below the surface of a pillar, the appropriate approach angle limits would be those applicable to the appropriate pillar. Therefore, in the case of the vehicle shown in the photographs attached to your message, in which the anchorage is located above the surface of the pillar, the proper approach angle limits would be those applicable to seat belt anchorages.

    I hope that this is responsive to your inquiry. If you have any questions or comments, please contact Otto Matheke of this office at (202) 366-5253.

    Sincerely,

    Jacqueline Glassman
    Chief Counsel

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    d.6/9/03