Metro is looking into yet another case of a “friction ring” falling from a train.

The transit agency said Wednesday morning that the part was found during a routine inspection, rather than being reported by a customer or a Metro employee.

The friction ring, a part of the braking system, was found near the Rhode Island Avenue station on the Red Line. The part showed no signs of failure, but the bolts that attach the ring to the car were broken, according to Metro. The rail car in question has been taken out of service.

This is the latest incident involving friction rings falling from cars. A friction ring fell from a rail car in December, snarling service on the Orange and Blue lines and prompting an investigation. Another friction ring fell from a Metro train in January.