Federal Motor Vehicle Safety Standards; Roof Crush Resistance

This document revises the test procedure in Standard No. 216, Roof Crush Resistance, to make it more suitable to testing vehicles with rounded roofs or vehicles with raised roofs. The test procedure is intended to test the strength of the roof over the front seat occupants by forcing a large flat steel test plate down onto the roof, simulating contact with the ground in rollover crashes. However, when the procedure is followed in testing certain vehicles with rounded roofs (e.g., the Ford Taurus), the test plate is positioned too far back and does not test the roof over the front occupants. In addition, that positioning creates the potential for contact between the front edge of the test plate and the roof. Such contact is undesirable because the front edge can penetrate the roof structure in a way that the ground cannot during rollover crashes. Similarly, for vehicles with raised, irregularly shaped roofs (such as some vans with roof conversions), the initial contact point on the roof may not be above the front occupants, but on the raised rear portion of the roof, behind those occupants. In both of these cases, the positioning of the plate relative to the initial contact point on the roof, instead of a fixed location on the roof, results in too much variability in the plate positioning and reduces test repeatability. This final rule addresses the problem of rounded roofs by specifying that, for all vehicles except those with certain modified roof configurations, the test plate is to be positioned so that the front edge of the plate is 254 mm (10 inches) in front of the forwardmost point of the roof. Positioned in this way, the front edge of the plate will always project slightly forward of the roof instead of contacting it. Further, the plate will always be positioned over the front occupants. The rule addresses the problem for vehicles with raised or modified roofs by specifying that if following the normal test procedure results in an initial point of contact th