Interpretation ID: nht87-1.17

TYPE: INTERPRETATION-NHTSA

DATE: 07/13/87

FROM: AUTHOR UNAVAILABLE; Erika Z. Jones; NHTSA

TO: Dr. Ernst; Hella KG Hueck & Co.

TITLE: FMVSS INTERPRETATION

TEXT:

Dr. Ernst Hella KG Hueck & Co Postfach 28 40 4780 Lippstadt GERMANY

Dear Dr. Ernst:

This is in reply to your letter of February 5, 1987, to Richard Van Iderstine of this agency's Office of Vehicle Safety Standards. You have asked for an interpretation of Motor Vehicle Safety Standard No. 108 with respect to a new headlamp manufactured by Hella that BMW has installed on a new car which it introduced in the United States around April 1, 1987.

The headlamp is of the replaceable bulb type, and as you describe it consists of two additional parts: "the housing, to which the cover lens is bonded by means of a two "component adhesive", and 'the optical module, consisting of the reflector and the convex lens, joined by the lens carrier...." In your words, "The two parts are held together by three screws", and you believe that "the two parts, firmly screwed together, are as effectively joined as would be the case if bonded".

Paragraph S3 of Standard No. 108 defines a "replaceable bulb headlamp" in pertinent part as "a headlamp comprising a bonded lens and reflector assembly. . . ." In the Hella design, the lens and reflector assembly are not bonded, and thus the headlamp is not a "replaceable bulb headlamp" that is permissible for use on motor vehicles sold and used in the Unite States. The intent of the definition is to ensure that the headlamp lens and reflector are an integral replaceable unit, since that is the only means to assure a mechanically aimable replaceable bulb headlamp which is capable of using any replacement standardized replaceable light source and meets the necessary photometric performance. The foundation of mechanical aimability is that the beam and aiming pads are manufactured to have a specific relationship. If this relationship is altered by replacement of the lens only, or of the reflector only, there is a high likelihood that the lamp may not meet minimum performance requirements when aimed mechanically.