Thomas D. Turner, Manager
402 Blue Bird Boulevard
Fort Valley, GA 31030
Dear Mr. Turner:
This responds to your request for an interpretation of the head impact zone requirements of Federal Motor Vehicle Safety Standard (FMVSS) No. 222, School bus passenger seating and crash protection, applying to small school buses (school buses with a gross vehicle weight rating of 4,536 kg or less). You ask how we position the drivers seat back when the school bus passenger head protection zone specified in the standard might include some areas in the drivers seating position. You suggest that the drivers seat back should be adjusted to its most upright position. It is our opinion that the school bus must meet impact zone requirements when the drivers seat back is in any position, not just the most upright position.
The test conditions for the head impact protection and other requirements of FMVSS No. 222 are specified in S6 of the standard. For a school bus with a GVWR of 4,536 kg or less, the test conditions apply when testing "all seating positions other than the drivers seat". Although S6.4 specifies that "If adjustable, a seat back is adjustable to its most upright position," that provision applies only to the adjustment of passenger seat backs.
S5. (b) of FMVSS No. 222 specifies that small school buses (school buses with a gross vehicle weight rating of 4,536 kg or less) must meet certain requirements of the standard "at all seating positions other than the drivers seat," including the requirements of S5.3, "Impact zone requirements".As you note in your letter, NHTSAs longstanding position has been that the head protection zone requirements extend to all contactable surfaces in the zone, including the drivers seat. (March 27, 1979, letter to Blue Bird Body Company; May 11, 1977, letter to Wayne Corporation.) To ensure that head protection is provided to passengers seated behind the driver regardless of how the driver positions his or her seat, in conducting the head impact protection test we will not limit the adjustment of the drivers seat back only to the most upright position. The agency will test the school bus to the head protection zone requirements with the drivers seat back adjusted to any upright or reclined position to which the seat can be adjusted.
In your letter, you state that the drivers seat for FMVSS No. 222 testing should be positioned as in other crashworthiness FMVSSs that specify that the drivers seat is tested in its nominal design driving position. Unlike the other crashworthiness standards you mention, FMVSS No. 222s protections extend to passengers rearward of the driver. FMVSS No. 222 has to ensure that reclining the drivers seat back does not negate or reduce the protection provided to those passengers.
I hope this information is helpful. If you have any further questions, please feel free to contact Dorothy Nakama of my staff at this address or by telephone at (202) 366-2992.
Stephen P. Wood
Acting Chief Counsel