OTTAWA -- A loose gearbox has gotten the blame for the Sept. 19 train derailment on Ottawa's Confederation Line LRT.

The derailment, the second in six weeks, happened approximately half a kilometre away from Tremblay Station, just beyond the rail bridge over Riverside Drive. The Transportation Safety Board reported that the train derailed before entering Tremblay Station and continued in the derailed state over the bridge before hitting a signal mast and switch heater.

Speaking to city council on Wednesday, City Manager Steve Kanellakos said the Rideau Transit Group told the city, "The bolts that secure the gearbox to the (light rail vehicle) were not torqued properly or verified, according to Alstom."

The gearbox came loose and was dragged along the track, Kanellakos said.

The LRT has been shut down completely since the Sept. 19 derailment, but Kanellakos said there is currently no timeline for a return to service.

The Rideau Transit Group must present the city with a return-to-service plan, which needs to be vetted independently by Philadelphia-based TRA Inc. before any trains will run again on the line.

"Once we receive the date from RTG, the city will not accept the return to service for the O-Train Confederation Line until TRA completes its review and provides its recommendations to the city for consideration and acceptance," Kanellakos said. "We need this system back up as soon as possible but it must be both safe and reliable."

Kanellakos added that the infrastructure repairs on the line should be completed by this week. The TSB said last week that the train car caused damage inside Tremblay Station and along the tracks stretching back to St. Laurent Station before it eventually stopped west of Riverside Drive.

In September, representatives from Rideau Transit Maintenance suggested shortly after the Sept. 19 derailment that it could take approximately three weeks before service might resume. 

The Sept. 19 derailment came less than two months following a derailment on Aug. 8 near Tunney's Pasture Station.

No one was hurt in either derailment. The train involved in the Aug. 8 derailment was out of service and headed back to the maintenance yard, but there were 12 passengers and an operator on the train that derailed on Sept. 19.