Interpretation ID: nht78-1.34

DATE: 01/25/78

FROM: AUTHOR UNAVAILABLE; J. J. Levin, Jr.; NHTSA

TO: Blue Bird Body Company

TITLE: FMVSS INTERPRETATION

TEXT: This responds to your October 24, 1977, letter asking whether the framework of a roof hatch must comply with the requirements of Standard No. 221, School Bus Body Joint Strength.

The terms which establish the applicability of the requirements of the standard to a particular section of school bus body are defined in S4 of the standard. Read together they establish the following test. If the edge of a surface component (made of homogeneous material) that encloses occupant space in a bus comes into contact or close proximity with any other body component, the requirements of S5 apply, unless the area in question is designed for ventilation or another functional purpose, or is a door, window, or maintenance access panel. Applying this test to the frame of a roof hatch, it appears that this joint need not comply with the requirements. This conclusion is reached because the National Highway Traffic Safety Administration concludes that a roof hatch is equivalent to a door or window for the purposes of the application of the requirements. The joint connecting the frame of a door, window, or roof hatch to a bus body falls within the exception to the applicability of Standard No. 221.

SINCERELY,

BLUE BIRD BODY COMPANY

October 24, 1977

Joseph J. Levin, Jr. Chief Counsel National Highway Traffic Safety Administration

Dear Mr. Levin:

The purpose of this letter is to get an interpretation regarding the applicability of FMVSS 221 relative to roof hatch emergency exit components.

The attached photos show a roof hatch viewed from inside the bus and from the roof of the bus. We would like confirmation of our interpretation that the metal framework of the roof hatch opening, shown in the attached photos, enclosing the edges of the roof opening are for a "functional purpose" as used in FMVSS 221, paragraph S4 and are, therefore, not subject to the requirements of that standard.

We will appreciate your early reply.

Thank you.

W. G. Milby Manager, Engineering Services

CC: JIM MOORMAN; JIM SWIFT; GARY MOYSES; TOM TURNER

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