A Charlotte-Mecklenburg school bus lost its rear wheels in morning traffic Tuesday because a technician failed to properly tighten lug nuts after brake repairs, the district said Wednesday.
The bizarre breakdown damaged a car and left a busload of Garinger High students sitting in a disabled bus on busy Eastway Drive on the second day of school. A CMS safety inspection report showed that the 6-year-old bus, with about 120,000 miles on it, had brake repairs on Aug. 17.
“After the brake replacement work was complete, the lug nuts were not tightened to standard using a torque wrench,” said a statement Charlotte-Mecklenburg Schools sent the Observer. “The torque wrench is a specific tool used to tighten bolts, nuts and fasteners which have a specific value to ensure optimum performance. The failure to adequately torque the lug nuts resulted in the rear wheels separating from the vehicle during transport.”
The state’s top school bus safety official said Wednesday it’s virtually unheard of for a school bus to lose its wheels, and the results could have been far worse. But he said there’s no indication that CMS has a widespread problem that would lead to a repeat.
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“You can tell based on the damage: You absolutely want your wheels to always stay attached to your vehicle,” Kevin Harrison, transportation section chief for the North Carolina Department of Public Instruction, said after talking with the CMS transportation director and seeing photos of a car hit by a bus wheel. Wheels that come loose on the road could be deadly, he said: “They are large and they are heavy and they have momentum.”
CMS said all bus mechanics, including the one whose failure caused the bus accident, are getting a refresher course on proper use of the torque wrench used to change and mount tires. And other buses that employee has worked on are being rechecked to ensure safety.
“All of our drivers perform a daily pre-trip and post-trip inspection that includes a visual inspection of the tires; this includes looking at tires for damage and wheel lug and rims,” said Transportation Director Janet Thomas. “As a part of our ongoing maintenance program, we continue to conduct 30-day inspections and the required preventative maintenance.”
CMS has 126,000 students riding 1,078 buses this school year, a number that keeps growing as the district expands academic options that often require long rides. The district has struggled to find enough drivers and mechanics to meet the need. As of Wednesday, 13 of the district’s 99 positions for bus maintenance and repair remained vacant, including 10 technicians and three service truck operators.
The employee who made the error was not a new hire, Thomas said.
Harrison, the state official, said he reviewed the maintenance history for Bus 1553, which lost the wheels, as well as last year’s report on a sampling of CMS buses that were inspected. While that report showed an increase in defects over the prior year and a worse-than-average safety rating, Harrison said he did not find any record of wheel or tire issues that would indicate a systemic problem.