Interpretation ID: nht92-8.26

DATE: March 16, 1992

FROM: Shigeyoshi Aihara -- Manager, Information Services, Ichikoh America, Inc.

TO: Paul Jackson Rice -- Chief Counsel, NHTSA

TITLE: Subject: Interpretation of FMVSS No. 108, paragraph S7.4(i)(6)

ATTACHMT: Attached to letter dated 5/6/92 from Paul J. Rice to Shigeyoshi Aihara (A39; Std. 108)

TEXT:

We would like to ask for your judgment concerning fogging after humidity test of replaceable bulb headlamp specified in FMVSS No.108, paragraph S7.4(i)(6).

Paragraph S.7.4(i)(6) is defined as follows:

"After a humidity test conducted in accordance with paragraph S8.7, the inside of the headlamp shall show no evidence of delamination or moisture, fogging or condensation visible without magnification, and the headlamp shall meet the photometric requirements applicable to the headlamp system under test."

Our questions concern the sentence "the inside of the headlamp shall show no evidence of delamination or moisture, fogging or condensation visible without magnification, and the headlamp ---"

A drawing of our headlamp with on-board aiming system is attached to this letter. The headlamp is a vented system. The bubble indicator cover of types A and B differ as shown in the attached sketches.

Question 1: After the humidity test, both types A and B show the fogging in the location as shown in attached sketches. But, this fogging is gone at normal temperature. We think this fogging does not affect the performance of headlamp such as bubble indicator visibility, photometry and others. Is such fogging acceptable after the humidity test ?

Question 2: May we understand that "the inside of housing" means the lens and reflector portions?, or Must we understand it to mean the entire inside portion of headlamps?

Your prompt reply would be greatly appreciated.