Interpretation ID: nht94-3.87

TYPE: INTERPRETATION-NHTSA

DATE: August 5, 1994

FROM: John Womack -- Acting Chief Counsel, NHTSA; Stamped signature by Kenneth N. Weinstein

TO: William G. Franz -- Vice President Fabrication, Wells Aluminum Corporation

TITLE: NONE

ATTACHMT: Attached to letter dated 4/4/94 from William G. Franz to Walter Myers (OCC 9857)

TEXT: Dear Mr. Franz:

This responds to your letter addressed to Mr. Walter Myers of this office requesting an interpretation of window opening size as provided in paragraph S5.1.2, Federal Motor Vehicle Safety Standard (FMVSS) No. 217, Bus Emergency Exits and Window Retention and Release. I apologize for the delay in responding.

You explained that Wells Aluminum Corporation manufactures pushout windows for the school bus industry. You asked whether the 8-inch window opening size referred to in paragraph S5.1.2 applies to the "total outside frame dimension" or to each pane of gl ass. "In other words, would a pane of glass which measures less than 8 inches across need to be subject to the retention test [of S5.1 of FMVSS No. 217]?" To illustrate your question, you enclosed with your letter a picture of an upper/lower-pane pushou t window which was positioned for a retention test.

To be excluded from Standard No. 217's window retention requirement, the entire window, and not just a pane of the window, must be less than the 8-inch window opening size described in S5.1.2 of the standard. Section 5.1 of FMVSS No. 217 specifies reten tion requirements for windows other than windshields in buses. Paragraph S5.1.2 provides that those requirements do not apply to "a window whose minimum surface dimension measured through the center of its area is less than 8 inches." This exemption of 8 -inch windows was included in the standard in the final notice establishing the standard, published in the Federal Register on May 10, 1972 (37 FR 9394). In the preamble to that notice the agency stated at 37 FR 9395:

Since there is little likelihood of passenger ejection or protrusion from window openings whose minimum surface dimension measured through the center of the area is less than 8 inches, an exemption for windows of this size has been granted (emphasis adde d).

2

It is clear that the intent of the agency in providing this exemption was to exempt window openings, as measured by the perimeter of the window, not just individual panes of glazing material. A window can be composed of more than one pane of glazing mat erial, such as the window in the picture you provided, where 1 or more individual panes may have a minimum dimension smaller than 8 inches, but the whole window is larger than 8 inches. Regardless of the size of the individual panes which make up a wind ow, passenger ejection or protrusion could occur through such a window opening. Since ejection through such a window is precisely what the standard was intended to prevent, S5.1 would apply.

We note that you did not explain what you meant by "total outside frame dimension" and the meaning of the quoted phrase is not entirely clear. We assume you meant the entire window opening which, for the window in your picture, would include the combina tion of both panes and the window frame. Thus, for purposes of S5.1.2, we would measure both the pane and the window frame.

I hope this information is helpful to you. Should you have any further questions or need any further information, please feel free to contact Mr. Myers at this address or at (202) 366-2992.

ncc-20WMyers; mar:7/25/94:62992:OCC 9857 Ref:217 U: NCC20 INTERP 217 9857.WKM Greenbook: (2); Interps: Std. 217 Coord: NRM, NEF