Mr. Robert L. Douglas
Director of Product Integrity
751 South Harkrider
Conway, AR 72032
Dear Mr. Douglas:
This responds to your request for an interpretation of whether an "aluminum extrusion" to be used to mount the upper longitudinal edge of the light bar is excluded from the definition of "body panel joint" as set forth in Federal Motor Vehicle Safety Standard No. 221, School Bus Body Joint Strength. Our answer is yes.
Standard No. 221 requires, among other things, that each body panel joint, when tested in accordance with the procedure of S6, shall hold the body panel to the member to which it is joined when subjected to a force of 60 percent of the tensile strength of the weakest joined body panel determined pursuant to S6.2 (S5.1). Standard No. 221 defines "body panel joint" as:
the area of contact or close proximity between the edges of a body panel and another body component, including but not limited to floor panels, and body panels made of composite materials such as plastic or plywood, excluding trim and decorative parts which do not contribute to the strength of the bus body, members such as rub rails which are entirely outside of body panels, ventilation panels, components provided for functional purposes, and engine access covers.
You state that your company is considering changing the method of mounting the upper longitudinal edge of a light bar. You will be replacing screws with an aluminum extrusion to insert and retain the upper longitudinal edge of the light bar. The aluminum extrusion will be attached to the roof inner liner with screws.
Our opinion is that the aluminum extrusion is a "trim" part and thus is excluded from FMVSS No. 221. The extrusion is similar to the plastic wire trim parts that NHTSA, in an August 31, 2000, letter to Mr. Thomas Turner, determined were trim. The aluminum extrusion does not contribute to the structural integrity or joint strength of the bus. As a manufacturer, however, it is your responsibility to secure the extrusion in such a manner that it is not likely to come unattached and cause injuries in a crash.
If you have any further questions, please feel free to contact Dorothy Nakama of my staff at this address or at (202) 366-2992.