NHTSA has  not developed such standards because it has not identified significant  problems with occupant restraint systems that could be addressed by state  motor vehicle inspection programs. Although  NHTSA has the authority to regulate aftermarket crash parts, the agency  has not developed safety standards for them because it has not determined  that any aftermarket crash parts contain safety-related defects. NHTSA has  more limited authority to regulate the use of recycled airbags. NHTSA  could elect to develop safety standards for occupant restraint systems  under the used vehicle provisions of the Motor Vehicle Safety Act. These limitations may hamper  NHTSA’s ability to detect safety-related trends through broad key-word  searches of its complaint database and make it unlikely that NHTSA can  identify all unsafe parts. In addition, the ability to recall unsafe aftermarket  crash parts is limited because some parts are not stamped with the  manufacturer’s name and there is no trail leading from the manufacturer to  the ultimate user of the part. The two studies on the safety of recycled airbags that we identified  concluded that they can be a potentially safe, economical alternative to  new airbags as long as they are undamaged and properly handled and  installed. However, the failure of some flood-damaged air bags to deploy  correctly also demonstrates the potential for serious safety consequences.
What GAO Found

Although the National Highway Traffic Safety Administration (NHTSA) has the authority to regulate aftermarket crash parts, the agency has not developed safety standards for them because it has not determined that any aftermarket crash parts contain safety-related defects. NHTSA has more limited authority to regulate the use of recycled air bags. NHTSA could elect to develop safety standards for occupant restraint systems under the used vehicle provision of the Motor Vehicle Safety Act. NHTSA has not developed such standards because it has not identified significant problems with occupant restraint systems that could be addressed by state motor vehicle inspection programs. The limitations of NHTSA's complaint system may hamper NHTSA's ability to detect safety-related trends through broad key-word searches of its complaint database and make it unlikely that NHTSA can identify all unsafe parts. In addition, the ability to recall unsafe aftermarket crash parts is limited because some parts are not stamped with the manufacturer's name and there is no trail leading from the manufacturer to the ultimate user of the part. Two studies on the safety of recycled airbags concluded that they can be a potentially safe, economical alternative to new airbags as long as they are undamaged and properly handled and installed. However, the failure of some flood-damaged airbags to deploy correctly also demonstrates the potential for serious safety consequences.