Many of the new streetcars delivered to Toronto significantly past deadline by Bombardier will be taken out of service and sent to Quebec to fix a "welding problem," the TTC said Wednesday.

Sixty-seven streetcars need to be fixed, according to Toronto Transit Commission spokesperson Brad Ross. To date, Bombardier has delivered 89 cars of a 204-car, $1-billion order originally placed in 2009.

The problem with the streetcars is not a safety issue, Ross said, but rather a welding irregularity that will affect the cars' guaranteed service life of 30 years.

Crews at Bombardier will need to strip the cars down to their frames and reweld the problem areas, a process that is expected to take as many as 19 weeks per car.

Three to four streetcars at a time will be sent to Bombardier's plant La Pocatière, Que., for repair. Ross said TTC riders won't see a "disruption in service" during the work, which could take until 2022 to complete.

You can listen to Metro Morning's full interview with Ross in the clip below.

Bombardier notified the TTC of the problems with the cars in October 2017, according to Ross. The transportation manufacturing giant will cover the additional costs of the repairs, he added, or else the TTC will seek compensation.

Toronto's mayor feeling 'extreme frustration' with streetcar issues

In a statement, Toronto Mayor John Tory said TTC executives are working closely with Bombardier to ensure the work goes smoothly.

"I have made no secret about my extreme frustration with this streetcar deal that was signed by a previous city council back in 2009 and Bombardier's slow progress in actually delivering the vehicles bought and paid for by Toronto taxpayers," Tory said.

"TTC CEO Rick Leary is working with Bombardier to ensure these repairs will have little to no impact on our service, and we have been assured this will not affect the delivery of new streetcars."

All 204 of the new streetcars are scheduled to be delivered by the end of 2019. In October 2015, the TTC board voted to sue the company over multiple production and delivery delays.

Bombardier has since added a second production line in Kingston, Ont., to ensure upcoming deadlines are met.