The Project 877EKM Kilo-class submarine had been undergoing a refit at the Zvezdochka shipyard in Severodvinsk since 2005.
The overhaul was delayed for six months due to the unacceptable performance of its new SS-N-27 Club-S cruise missiles. In six consecutive pre-delivery test firings in September - November 2007, the Club missiles failed to find their targets and India refused to accept the delivery until all the problems had been fixed.
The Club-S subsonic cruise missile is designed for launch from a 533 mm torpedo tube, or a vertical launch tube. It has a range of 160 nautical miles (about 220 km). It uses an ARGS-54 active radar seeker and Glonass satellite and inertial guidance.
The new trials were completed in mid-July and were successful.
Sindhuvijay is the 4th Indian navy submarine to have been refitted at the Zvyozdochka shipyard.
The upgrade program also involved a complete overhaul of the submarine, including its hull structure, as well as improved control systems, sonars, electronic warfare systems, and an integrated weapon control system. The upgrades reportedly cost about $80 million.
Russia's Kilo-class diesel-electric submarines have gained a reputation as extremely quiet boats, and have been purchased by China, India, Iran, Poland, Romania and Algeria.