Nilgiri-class frigate (1972)  The "Nilgiri"-class frigates were updated versions of the , designed and built for the Indian Navy by Mazagon Dock Limited in Mumbai. Six ships were built between 1972–81. Vessels of the class formed the 14th Frigate Squadron. The lead ship was the first major warship to be built in India in collaboration with Yarrow Shipbuilders of the United Kingdom. The class and its lead ship, INS "Nilgiri" are named for the Nilgiri Hills. Subsequent ships in the class are also named for hill ranges of India. When the British refused to provide license production of the radar suite, the Indian Navy teamed up with Signaal of Netherlands to license-build a similar radar search, tracking and fire control suite in India, which went into the latter five ships. Improved versions of the Signaal search radar continues to be fitted in later classes of Indian Navy ships. The last two ships, and were modified significantly with the addition of a Sea King ASW helicopter, a collapsible Canadian hangar, ILAS 324 mm triple torpedo tubes and a Bofors ASW twin barrel mortar. This re-design was done indigenously by the Indian Navy and gave it much needed experience and confidence in ship-design and modification. They were also fitted with an indigenous ASW fire control action information system which was a first for the Indian electronics industry. This project was led by Captain (later Rear Admiral) Prakash N Gour. The British categorically refused to extend their design warranty to the Indian modifications which nevertheless proved to be a success. The "Nilgiri" class has been decommissioned by the navy, with the entry into service of the . Five ships have been decommissioned and one sunk in an accident. INS "Taragiri" was the last ship of the class to be decommissioned, on 27 June 2013 in Mumbai, after serving 33 years in the navy. In November 1960, construction of three "Leander"-class frigates were approved by the government of India. The first frigate was ordered in July 1965 and the next two were ordered in September 1967. Three more frigates were ordered in July 1970. The "Nilgiri"-class frigates served as the mainstay and workhorse of the Indian Navy during the 1980s and early 1990s and they formed the 14th Frigate Squadron. The last two vessels ("Taragiri" and "Vindhyagiri") had more powerful engines than the earlier vessels.