Federal safety regulators have begun investigating buses made by Motor Coach Industries Inc. over the past 20 years because the drive shafts can fall out and cause drivers to lose control.
The problem has led to two crashes that killed two people and injured 50 others, according to documents filed Monday on the National Highway Traffic Safety Administration's website. The probe covers an estimated 4,000 MCI D-Series buses with a steerable rear axle made from 1992 until this year.
Schaumburg, Ill.-based MCI says on its website that it's the leading maker of intercity buses in the U.S. and Canada.
Messages were left for company officials for comment.
The probe stems from a complaint filed with NHTSA by transportation company FirstGroup America, parent of Greyhound bus lines. The company said several drive shafts failed on MCI buses starting in March 2010, and the shafts were not held up by safety loops that are supposed to keep them in place. In two cases, drivers lost control of the buses, causing multiple injuries and fatalities, the complaint said.
On March 16, 2010, an Americanos USA bus operated by Greyhound crashed on Interstate 37 near San Antonio, killing two and injuring 40 others. The Texas Department of Public Safety said it was likely the drive shaft broke before the bus veered wildly and flipped over. It was carrying spring breakers and other travelers to Matamoros, Mexico.
A bus expert said at the time that drive shafts rarely break and completely fall off, but the shafts can snag on the pavement and turn a bus over.
Testing by Cincinnati-based FirstAmerica found that the drive shafts can fall on the MCI buses and damage safety systems such as brake lines, NHTSA documents said.
NHTSA said it is looking into whether the buses have a safety defect. An investigation can lead to a safety recall, but no vehicles have been recalled yet. The safety agency said Monday that it will share its work when the investigation is done.
In the San Antonio crash, Christina Lozano Campos, 62, of Lewisville, Texas, and Efrain Dominguez-Valenzuela, 27, of Brownsville, Texas, were killed. Two others were critically injured. The bus driver was not charged in the case.