The recall affects 53,528 Thomas Built school buses from model-years 2014 through 2020, including Thomas Built Saf-T-Liner EFX, Minotour, Saf-T-Liner C2, and Saf-T-Liner HDX school bus models.
The bus seat backs were made with styrene blocks that do not provide enough impact absorption around the back of the seat frame, in violation of the Federal Motor Vehicle Safety Standard.
In the event of a crash, children are more likely to suffer knee injuries.
The recalled buses are equipped with SynTec S3B or S3C seats.
Daimler Trucks North America, owner of the Thomas Built school bus company, will notify owners of recall. Dealers will add padding between the frame and the seat cover at no cost.
The recall is expected to begin on December 2. For more information, contact Daimler customer service at 1-800-547-0712.