Interpretation ID: 77-1.46

TYPE: INTERPRETATION-NHTSA

DATE: 03/17/77

FROM: AUTHOR UNAVAILABLE; F. Berndt; NHTSA

TO: Paulson and Humphrey

TITLE: FMVSS INTERPRETATION

TEXT: This responds to your February 3, 1977, letter asking whether the intersection of a plywood floor panel and the floor channel structure constitutes a "body panel joint" subject to 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 a school bus body are defined in S4 of the standard. Read together, they establish the following test. If the edge of a surface component (body panel) that encloses the bus' occupant space 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 joint you describe, it appears that the joint must comply with the requirements of the standard, because it is the connection of a body component (floor channel structure) with a body panel that encloses occupant space (plywood floor panel).

In your letter, you argue that the standard is not directed at these types of joints and that in fact the NHTSA stated that not all joints would be regulated by this standard. While it is true that not all joints are regulated by the standard, all joints between the edge of a body panel and a body component are regulated unless expressly excepted from coverage by the language of the standard itself. Since the joint you describe connects a body panel to a body component, it is exactly the type of joint for which coverage was intended.

Finally, you argue that all joints located below the floor are not covered by the standard. This is correct. However, the NHTSA has required floor panels regardless of composition to comply with the requirements of the standard, since these panels form the floor and do not fall below it.

SINCERELY,

PAULSON AND HUMPHREYS

February 3, 1977

Frank Berndt, Esquire Acting Chief Counsel National Highway Traffic Safety Administration

This is a request for interpretation of Federal Motor Vehicle Safety Standard No. 221, School Bus Body Joint Strength, submitted on behalf of the Gillig Corporation of Hayward, California.

We have examined the standard, as published January 27, 1976 and the NHTSA interpretive opinions to Blue Bird Body Company of April 14 and April 26, 1976 (N40-30). The conclusions which we express are based substantially on the foregoing. It will be appreciated if you will inform us as rapidly as may be feasible whether you agree with these conclusions or whether another interpretation is appropriate.

Enclosed are diagrams illustrating a possible form of construction of the floor elements of a school bus design (View #1 and View #2). In both diagrams you will note that the floor structure is formed by use of laminated plywood abutting, on either side, a steel channel structure. Over this floor structure is added a rubberized floor covering. In View #1 the mechanism used to attach the plywood to the steel channel structure is exhibited as one of several screws. In View #2, an adhesive is added between the bottom of the particular plywood panel and the abutting flange of the steel channel structure.

Gillig believes that either of the forms of floor structure described will provide adequate structural integrity for foreseeable crash conditions. Gillig wishes, however, to be sure whether the requirements of the standard apply to this structure.

The question which arises is whether, in the form of floor diagrammed, either the edge of the plywood panel abutting the steel channel (shown in the diagrams as "Joint A") or the bottom of the plywood panel as it rests on the flange of the steel channel (shown in the diagrams as "Joint B") constitute "body panel joints" as defined in FMVSS No. 221, paragraph S4. In other words, is the standard applicable to either of such "joints"?

It is our conclusion that neither of the joints described is a "body panel joint" within the purview of FMVSS No. 221. We base this conclusion on several things:

First, the definition of "Body component", in paragraph S4, imports that a component to be a "body component" must be of a "single piece" of either homogenous material or a "single piece" of composite material such as plywood. The form of structure exhibited in the diagrams would not seem to constitute a "body component" and thus would not be subject to joint strength requirements at any point and particularly at "Joint A" or "Joint B".

Second, the forces which might be exerted in a vehicle crash and to which the standard is directed would not seem adversely to affect joints like "A" and "B". Further, attempting to achieve the type of increased joint strength to which the standard is directed, i.e. through the addition of more rivets or other fasteners, would probably be impracticable, if not impossible, in the type of joints illustrated in the diagrams. The standard obviously is directed toward achieving essentially a strengthening of those joints between side panels and between side panels and certain other body components, such as the roof or rear wall. The Preamble to the proposed rule, as published March 13, 1975 (40 FR 50, page 11738), substantiates this conclusion in that it states that regulation of all joints has been tentatively determined to be impractical.

Finally, an interpretation is stated in the third paragraph at page 2 of the letter to Blue Bird of April 26, 1976 that components located entirely below the level of the floor line are not subject to the standard; but that where a portion lies above the floor line that portion is subject to the requirements of the standard.

Your early reply will be appreciated since the standard becomes effective on April 1, 1977.

Edmund C. Burnett

cc: J. M. DABROWSKI -- DIR. OF ENGINEERING; GILLIG

View #1

(Graphics omitted)

View #2

FLOOR COVERING

ADHESIVE

(Graphics omitted)