The Transportation Safety Board of Canada (TSB) wants to know what Rideau Transit Maintenance is going to do to prevent any future O-Train derailments.
The TSB sent a pointed letter to the consortium on Monday, September 27, calling its "preventive risk mitigation strategy" that relied on visual inspections "insufficient."
The letter also reveals new details about the O-Train derailment on August 8, including photos of a melted roller bearing cone on a wheel that came off the axle before the train derailed.
The TSB says that O-Train had been inspected for a different wheel problem just five hours before two of the axles on another train car came off the tracks near Tunney's Pasture.
Another train recently derailed on Sunday,September 19 near Tremblay Station but the TSB has not submitted its final report on this incident.
The TSB continues to investigate all Ottawa LRT derailments.