In 1971, her crew began receiving training in France, and became involved in events surrounding the East Pakistan when a mutiny took place in the ship to defect to Bangladesh. At the time her crew were receiving training thirteen of the crew were East Pakistanis who planned an operation to take over the submarine and try to defect to Bangladesh from France. "Mangro" was ordered to report back to submarine base in Karachi on 1 April 1971 but her plan to depart was interrupted when the 13 East Pakistani enlists decided to seized the submarine.