Interpretation ID: nht74-3.13

DATE: 01/03/74

FROM: AUTHOR UNAVAILABLE; Lawrence R. Schneider; NHTSA

TO: General Motors Corporation

TITLE: FMVSS INTERPRETATION

TEXT: This is in reply to your letter of December 3, 1973, requesting clarification of paragraph S5.1(c) of Motor Vehicle Safety Standard No. 217, "Bus Window Retention and Release." Your letter, and attached photograph of a push-out window, suggest that the words "window frame" in S5.1(c) refer not to the window "sash", the structure immediately surrounding the glazing material, but to the side of the bus.

We do not agree. The words "window frame" in S5.1(c), with respect to the push-out window, refer to the component that interfaces with the glazing.

The intent of S5.1 is to require a window retention system to be strong enough to retain occupants in a crash, at least up to the strength limit of the glazing itself. Since there are no limits on movement of the window "sash" relative to the bus structure, the interpretation you suggest would allow a window system that provides no retentive properties at all, thus defeating one of the main purposes of the standard.