Barely had it soaked in the proud moments of glory on the launch of India’s first indigenous aircraft carrier INS Vikrant; the Indian Navy was on Wednesday jolted by the loss of INS Sindhurakshak, a kilo class Russia-made submarine in an explosion and fire that engulfed it in naval dockyard in Mumbai.

Just three years ago INS Sindhurakshak had suffered another mishap when a fire had erupted on board, leaving a sailor dead and two others injured. The mishap was then blamed on an explosion in its battery compartment.

The submarine was bought from Russia as part of a deal in the early 1980s and it was commissioned in 1997. INS Sindhurakshak was the ninth of the ten diesel-electric submarines, which the Navy has in its submarine fleet of 16, including four German HDW submarines.

The Indian Navy also operates a nuclear-powered submarine INS Chakra, which is on lease from Russia. Six Scorpene submarines are now under construction at Mazagaon Dock in Mumbai and are likely to be made available between 2015 and 2018. The Scorpene is a diesel-electric attack submarine with additional air-independent propulsion jointly developed by the French shipbuilder DCN — now DCNS — and Spain's Navantia.

Reason for explosion

Vice Admiral (Retd.) A.K. Singh said an internal explosion in a submarine could be caused by either material failure or by not following the standard operating procedure (SOP). He suspected that the hydrogen gas generated during charging of the batteries of the submarine could have led to the fire, which in turn could have triggered the massive explosion.

Major setback to Navy

Terming the mishap as a major setback to the Navy, former Navy chief Admiral (Retd.) Sushil Kumar said that Sindhurakshak was a frontline submarine.

In 2008, another submarine of the Kilo class, INS Sindhugosh, had collided with a merchant vessel off Mumbai while participating in a naval exercise. In 2011, a surface warship INS Vindhyagiri had caught fire when it hit a merchant vessel near the Mumbai harbour.

The ill-fated submarine had recently undergone an upgrade at the cost of Rs. 480 crore with an improved weapons system. The refit was expected to have increased its life span by another 10 years. It had undergone an overhaul including structural hull upgrades at the Zvyozdochka shipyard in Russia. The Sindhurakshak — a Russian Type 877EKM submarine, Sindhughosh class submarine for the Indian navy — was constructed in Admiralteiskie Verfi shipyard in St. Petersburg in 1997.

It's one of 10 Kilo class submarines constructed in Russia's shipyards for the Indian navy from 1985-2000. It was delivered to India earlier this year after undergoing overhaul and refitting in Russia. The 2,300-tonne submarine was upgraded with an improved electronic warfare systems, control system and integrated weapon control system.

The Indian Navy has already ordered an enquiry into the mishap, which came within days of first indigenously built nuclear powered submarine, INS Arihant’s mini-nuclear reactor going critical.

Defence Minister A.K. Antony also condoled the death of naval personnel on the submarine. He briefed Prime Minister Manmohan Singh on the mishap before leaving for Mumbai. He said he was saddened at the tragedy of this magnitude which has happened in recent times.

“I also feel sad about those Navy personnel who lost their lives in the service of the country,” Mr. Antony told reporters in the Parliament House complex, shortly before rushing to Mumbai.

The Kilo class is the NATO designation for a naval diesel-electric submarine made in Russia. The original version of the vessels were designated Project 877 Paltus (Halibut) in Russia. Original Project 877 vessels are equipped with Rubikon MGK-400 sonar system, which includes a mine detection and avoidance sonar MG-519 Arfa. The first Kilo Class submarine entered service in the Soviet Navy in early 1980s.

These Kilo class submarines are 70-74 metres long and can travel at the maximum speed of 10-12 knots when surfaced and 17-25 knots when under water. The submarines are propelled by a diesel-electric engine which generates 4,400 kw of power. These vessels can remain in the sea for about 45 days at one stretch. Former Navy officers, familiar with submarine operations, said that such vessels can carry up to eight surface-to-air missiles and 18 torpedoes or 14 underwater mines.

The Sindhurakshak was armed with the latest export variant of the Russian-made submarine-specific Club-S multi-role cruise missile system capable of hitting targets more than 150 miles away. The Kilo class vessels can travel at around a maximum 20 mph at a depth of around 900 feet.

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