Kenneth M. Bush, Regulations Manager
Government Regulations Department
American Suzuki Motor Corporation
3521 East Imperial Highway
Brea, CA 92822-1100
Dear Mr. Bush:
This is in reply to your letter of May 30, 2002, asking whether a motorcycle headlamp design you are contemplating "complies with the requirements of S188.8.131.52(a)" of Federal Motor Vehicle Safety Standard No. 108.
The Suzuki design is a single headlamp with two light sources mounted on the vertical centerline. The upper light source incorporates both an upper and a lower beam filament. The lower light source "has only a single filament." You are considering two illumination methods.
In the first method, the lower light source is activated whenever the upper light source is activated on either the upper or lower beam filament. In the second method, the lower light source would be activated with the upper light source upper beam, but the lower beam would be provided only by the lower light source.
S184.108.40.206(a) specifies that a motorcycle headlamp system consisting of a single headlamp shall be mounted on the vertical centerline. If the headlamp contains more than one light source, each light source shall be mounted on the vertical centerline with the upper beam no higher than the lower beam. You believe that the first method meets S220.127.116.11(a) because"both light sources are illuminated for both high beam and low beam operation." We concur with your interpretation because the single upper light source contains both an upper and lower beam filament.
You ask whether the second illumination method also complies. In this case, only the lower light source provides the lower beam. Thus, the upper beam light source is higher than the sole light source providing the lower beam, and this design would not comply with S18.104.22.168(a).
If you have any questions, you may phone Taylor Vinson of this Office (202-366-5263).