THE MBTA said a four-day investigation revealed that an improperly installed bolt in a braking unit disabled one of the new Orange Line trains last week, prompting the transit authority to remove all the new trains from service.
In a statement issued Monday morning, the T said each of the 24 bolts per car and 144 per six-car-train set will be checked on the new vehicles cand they will be returned to service as they pass inspection.
The T said preliminary findings from its investigation indicate the disabled train had one bolt on one car that was installed improperly during the manufacturing and assembly process. “To this point in the inspection process, the issue has not been found in any other braking units,” the T said.
The decision to remove all of the new train sets from service came as officials from the Federal Transit Administration are on site at the MBTA investigating the agency’s safety practices.