USA: Updates to update FMVSS No. 207 “Seating systems”.

 

USA is considering an update of the Federal Motor Vehicle Safety Standards No. 207 “Seating systems”.

As part of its safety mission, NHTSA issues Federal Motor Vehicle Safety Standards (FMVSSs) and other regulations for new motor vehicles and equipment to save lives, prevent injuries, and reduce economic costs from road traffic crashes. All FMVSSs must comply with the National Traffic and Motor Vehicle Safety Act of 1966, meaning they must be practicable, meet the need for motor vehicle safety, and be stated in objective terms.

On November 14, 2021, the Infrastructure, Investment, and Jobs Act (IIJA) was passed. Section 24204 of the IIJA, “Motor Vehicle Seat Back Safety Standards,” directs the Secretary of Transportation to issue an advance notice of proposed rulemaking (ANPRM) within two years to update 49 CFR 571.207. The publication of this ANPRM fulfills this statutory mandate.

FMVSS No. 207 sets requirements for seats, seat attachment assemblies, and their installation in passenger cars, multipurpose passenger vehicles, trucks designed to carry at least one person, and buses. This standard, among other things, establishes minimum strength requirements for the seat back and its associated restraining devices and adjusters. While in its rearmost position, a seat back must withstand a rearward moment (torque) of 373 Newton-meters (Nm) (3,300 inch-pounds (in-lb)), applied by a horizontal force measured vertically from the seating reference point. The standard also includes a test procedure that specifies applying a rearward force on the uppermost cross member of the seat back structure, resulting in a moment applied to the attachment (often the recliner mechanism) of the seat back and the remainder of the seat structure.

FMVSS No. 207 also contains provisions dictating the strength of seat attachments to the vehicle in both the front and rear directions. For the purposes of this ANPRM, “strength” regarding seat backs refers to the maximum rearward moment or force a seat back can withstand. “Stiffness” refers to the resistance of the seat back to any (or a specified) amount of deformation and deflection. In other words, “stiffness” can be thought of as the increase in resistive force or moment per unit deformation or rotation. Rigidity is the characteristic of a structure, such as a seat back, exhibiting relatively limited deformation when exposed to a force. Rigid and yielding seat back structures are opposites.

Although FMVSS No. 207 sets the minimum seat back strength requirement, since 1968, the de facto minimum requirement for seat back strength has effectively been set by FMVSS No. 202 (now 202a), “Head Restraints.” This standard requires head restraints and establishes requirements to reduce the severity of neck injuries in rear-impact crashes. Currently, FMVSS No. 202a requires a fully extended head restraint to withstand an 890 Newtons (N) (200 pound-force (lb-f)) rearward load for 5 seconds, applied 65 millimeters (mm) (2.5 inches (in)) below its top when adjusted to its highest position, which must be at least 800 mm. This creates an effective torque requirement on the seat back of 654 Nm (5,790 in-lb), significantly higher than the 373 Nm (3,300 in-lb) required by FMVSS No. 207.

In addition to the requirement in the IIJA, this ANPRM addresses three petitions for rulemaking that NHTSA received, requesting various amendments to the FMVSS related to the deformation of seat backs in rear impacts.

To find out more about vehicle regulations in USA and the FMVSS, please do not hesitate to contact the Institute for Global Automotive Regulatory Research Directly.