Interpretation ID: mills.ztv

Mr. Robert G. Mills
Supervisor, Homologation and Publications
Triumph Motorcycles, Ltd.
Jacknell Road
Hinckley, Leicestershire LE10 3BS
United Kingdom

Dear Mr. Mills:

This is in reply to your fax of August 22, 2003, with reference to paragraph S7.9.6.2 of Federal Motor Vehicle Safety Standard No. 108.

You described a single motorcycle headlamp "with two separate illuminating compartments, one of which contains the lower beam and the other the upper beam." The projectors providing each beam would be mounted at the same height and symmetrically disposed around the vertical centerline of the motorcycle. When only the lower beam is activated, the lighting array would be asymmetric; however, the lower beam remains activated when the upper beam is activated, resulting in a symmetric lighting display. You are aware of our 1994 and 1995 interpretations to Jeffrey Shetler of Kawasaki which, in your view, "clearly indicate that an asymmetric lower beam coming from a single headlamp is not considered to comply with the standard." You have asked us to reconsider these interpretations in view of the fact that paragraph S7.9.6.2(c) permits asymmetrical lighting in a two-headlamp motorcycle headlighting system when an upper beam headlamp and a lower beam headlamp are mounted on either side of the vertical centerline.

Our previous letters to Mr. Shetler were based upon Table IV of Standard No. 108 as in effect in 1994 and 1995. Table IV stated that a motorcycle headlamp must be located "On the front, on the vertical centerline, except that if two are used they shall be symmetrically disposed about the vertical centerline." The headlamp described by Mr. Shetler would be mounted on the vertical centerline, but, as we informed him, "the beams provided by the headlamp are located on either side of the centerline and are therefore asymmetrical in relation to the centerline of the motorcycle when either beam is activated." We did not consider this a configuration that met Table IV.

However, since the time of those earlier interpretation letters, relevant changes have been made to FMVSS No. 108. Today, as a result of a 1998 final rule (63 FR 42582, August 10, 1998) that specifically allows asymmetrical headlamp beams on motorcycles, a single-headlamp beam configuration as you have described would comply with the requirements of S7.9.6.2(a). Furthermore, in this case, we note that all compartments that are wired to illuminate in the upper beam mode must be illuminated when determining compliance with the upper beam photometry requirements.

If you have further questions, you may refer them to Mr. Eric Stas of this office (202-366-5263).

Sincerely,

Jacqueline Glassman
Chief Counsel

ref:108
d.9/26/03