Interpretation ID: 22497-5ogm

Mr. Takashi Yoshie
General Manager
Toyota Technical Center, USA
1850 M Street, NW
Washington, DC 20036

Dear Mr. Yoshie:

This in response to your letter dated December 21, 2000, regarding the provisions of Federal Motor Vehicle Safety Standard No. 201, Occupant protection in interior impact, as they relate to determining the proper vertical approach angle to be used when testing targets located on safety belt anchorages.Specifically, you are concerned about how to determine the maximum vertical approach angle when testing a target located on a seat belt anchorage on a vehicles B-pillar. We regret any inconvenience that our delay in responding may have caused.

It is your companys view that in the case of a safety belt anchorage located on the B-pillar, the proper amount of downward rotation used to determine the maximum vertical approach angle for testing is ten degrees.This is the amount of rotation that the standard specifies for B-pillar targets. You are concerned, however, that some independent laboratories are interpreting the standard to specify that the amount of downward rotation is five degrees. This is the amount of rotation that the standard specifies for targets on safety belt anchorages. As discussed below, we interpret Standard No. 201 to specify that, in the case of a safety belt anchorage projecting above the surface of the B-pillar, the amount of downward rotation used to determine the maximum vertical approach angle for testing is five degrees. However, if the anchorage does not project above the surface of the B-pillar, the maximum vertical approach angle for testing is ten degrees.

As you know, Standard No. 201 establishes performance requirements for certain areas of vehicle interiors. These performance requirements are intended to reduce the risk of occupant head injury by ensuring that vehicle interiors have certain impact characteristics. Compliance with these performance requirements is tested through the use of a specially designed impactor, the free motion headform (FMH).The FMH, which is instrumented to collect impact data, is projected into certain target zones in the vehicle.

Standard No. 201 does not require that all areas of the upper interior of a vehicle be subject to compliance testing. The Standard sets forth a number of discrete target areas that are to be impacted by the FMH. All of these 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.

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. That table separately lists, among other targets, the left B-pillar, right B-pillar, and seat belt anchorages.

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. To allow a determination of the maximum vertical approach angle for a particular target, S8.13.4.2(b)(1) and S8.13.4.2(b)(2) provide specific directions for determining the maximum vertical approach angle used.S8.13.4.2(b)(1) - which applies to all targets except B and other pillar targets - specifies that the maximum vertical approach angle is determined by rotating the FMH downward by 5 degrees while keeping the forehead impact zone in contact with the target circle.In the case of B and other pillars other than A-pillars, S8.13.4.2(b)(2) applies. S8.13.4.2(b)(2) directs that the FMH be rotated downward by 10 degrees with the forehead impact zone remaining in contact with the target circle if the target is on any pillar except an A-pillar. If the maximum vertical angle derived from the use of S8.13.4.2(b)(1) and S8.13.4.2(b)(2) is within the range of permissible vertical approach angles outlined in S8.13.4, a test may be conducted with respect to the target area in question.

It is your companys view that where a target is on a safety belt anchorage located on the B-pillar, the amount of downward rotation used to determine the maximum vertical approach angle for testing is ten degrees. This contention is based on the inclusion of safety belt anchorages as component parts of pillars in the definition of "pillar" within Standard No. 201. According to your argument, seat belt anchorages are part of a pillar under this definition and Target BP2 - which is any seat belt anchorage on a B-pillar - is not a safety belt anchorage target but is more properly a pillar target. You therefore believe that the degree of downward rotation used when establishing the maximum vertical approach angle should be ten degrees and not five degrees.

In reviewing your letter, we note that while you are correct that the standards definition of pillar includes attached components such as safety belt anchorages, it does not specify that the angle specifications for testing targets on pillars should take precedence over the angle specifications for testing targets on seat belt anchorages.

To resolve this issue, we have considered the policy reasons behind specifying special angle requirements for pillars other than A-pillars, and whether those reasons are relevant to seat belt anchorages located on such pillars.

In specifying that when calculating the vertical approach angles for B and other pillar targets there is a required offset of ten degrees of downward rotation, the National Highway Traffic Safety Administration sought to delay chin contact with the vehicle to allow appropriate HIC calculations. As the agency explained in the preamble to the August 1995 Final Rule (60 FR 43031, 43036, August 18, 1995), 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.However, 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 on the B-pillar, the amount of offset required to delay chin contact would depend, in large part, on the configuration of the particular anchorage.In those instances where a belt anchorage projects above the surface of the B-pillar, a ten degree offset would be unnecessary.In cases where the anchorage design results in BP2 being on or below the surface of the B-pillar, the same degree of offset used for other B-pillar targets - ten degrees - would be appropriate to prevent early chin contact.

Accordingly, we interpret the standard to specify that, in the case of a safety belt anchorage located so that it does not project above the surface of pillars other than A-pillars, the amount of downward rotation used to determine the maximum vertical approach angle for testing is ten degrees. In the instance of anchorages that project above the surface of the pillar, the amount of downward rotation used to determine the maximum vertical approach angle for testing is five degrees.

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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