Canada's only fully operational submarine departed Halifax Harbour Sunday after another round of mechanical trouble, Maritimes Forces Atlantic confirmed.

HMCS Windsor has been docked in Halifax for the last week for repairs to a diesel generator supercharger.

The sub now is on its way to a NATO exercise called Dynamic Mongoose, involving anti-submarine warfare, near Norway. The mechanical trouble delayed the submarine, which had scheduled a tour for international media on June 20. It's unclear when the submarine is expected to arrive.

Maintenance crews worked around the clock to replace a broken supercharger on HMCS Windsor, readying the submarine to head back out to sea. (Brett Ruskin/CBC)

Mechanical troubles

The supercharger problem was noticed around St. John's as the sub was first headed to the exercise. The broken supercharger previously was called important, but not critical, by the ship's commander.

The submarine's maintenance crews worked long hours stocking the ship with trip supplies and fixing the supercharger.

Only a few months ago, the Windsor cut an exercise short after crew members saw smoke when a battery cell malfunctioned.

In January 2015, the submarine returned to service after months of unscheduled repairs and maintenance, which came to around $17.2 million. That was soon after a $209-million refit was delayed by a faulty generator.

Military officials were not available for an interview.