Interpretation ID: nht90-3.64

TYPE: Interpretation-NHTSA

DATE: August 22, 1990

FROM: M. Iwase -- General Manager, Technical Administration Dept., Koito Manufacturing Co., Ltd.

TO: Erika Z. Jones -- Chief Counsel, NHTSA

TITLE: Re FMVSS No. 108 (Lamps, reflective devices, and associated equipment) Procedure of Re-calibration for Replaceable Bulb Headlamp with VHAD

ATTACHMT: Attached to diagram entitled Re-Calibration Procedures in The Shops (graphics omitted); Also attached to letter dated 10-3-90 from P.J. Rice to M. Iwase (A36; Std. 108)

TEXT:

FMVSS No. 108 specifies in S7.7.5.2(a)(2)(iv) that the horizontal indicator of VHAD shall be capable of re-calibration over a movement of +-2.5 degrees.

We would like to confirm your interpretation concerning the method and procedures of re-calibration on the vehicle after repair from accident damage.

Enclosed please find a copy of Federal Register dated February 8, 1990 (Page 4425 and 4426), in which NHTSA interprets, as follows;

If the dimensional specifications of vehicle body and appropriate instruction are described in shop manual, re-calibration could be addressed.

However, we don't believe that the method mentioned in the NHTSA's interpretation is practicable, with the following reasons;

(1) There may be some case that linear measurement of distance will be unable to be taken between reference points on vehicle body and headlamp units, owing to interruption of some other parts in engine room.

(2) Even if possible to measure linearly, we are afraid that it will be difficult to measure it precisely.

Therefore we are going to adopt a method of addressing for re-calibration in which headlamp with it's lens being masked partially are lit and visually aimed with the help of photometric beam pattern on the screen. (see Fig. 1 and the enclosed pictures). Our experiment proved that the visually aiming by photometric beam pattern be practicable.

We are fully aware that this method needs some space of 3 meters or so between illuminated headlamps and the scren (see Fig. 2) for clear image of beam pattern, which is not necessarily possible to accomodate in every case.

Therefore we are preparing Shop Manual in which both methods of NHTSA's dimensional data and our proposing visual aiming by photometric beam pattern are prescribed, and presenting the optional alternative of the above two methods. We intend to provide a masking sheet for the visual aiming, with Shop Manual.

We would be greatly appreciate it if you would kindly advise us whether our proposal could go along with NHTSA's intention.

Thanking you for your kind and prompt reply, in advance, we remain, with best regard, yours very truly.

Attachment is entitled Re-Calibration Procedures in The Shops (graphics omitted).