The Kamov Ka-27 (NATO reporting name 'Helix') is a military helicopter developed for the Soviet Navy, and currently in service in various countries including Russia, Ukraine, Vietnam, China, South Korea, and India. Variants include the Ka-29 assault transport, the Ka-28 downgraded export version, and the Ka-32 for civilian use. Design and development The helicopter was developed for ferrying and anti-submarine warfare. Design work began in 1969 and the first prototype flew in 1973. It was intended to replace the decade-old Kamov Ka-25, and had to have identical or inferior external dimensions compared to its predecessor. Like other Kamov military helicopters it has coaxial rotors, removing the need for a tail rotor. In total, five prototypes and pre-series helicopters were built. Series production started at Kumertau in July 1979, and the new helicopter officially entered service with the Soviet Navy in April 1981. The Ka-27 has a crew of three with a pilot and a navigator both installed in the cockpit, and a sonar operator installed behind. It has a four-leg fixed landing gear. The Ka-27 is equipped with two lateral buoys, that can be inflated in the case of a forced landing on water. The Ka-27PL anti-submarine version is equipped with a radar, and either a dipping sonar or a magnetic anomaly detector. It can also carry either up to 36 sonobuoys, or a torpedo, or between six and eight conventional depth charges, or a single nuclear one. Ka-27PLs generally operate in pairs as hunter-killer teams. The Ka-27PS search and rescue helicopter can carry 12 folding seats or four stretchers in its cabin, and is equipped with a 300-kg winch. Its fuel capacity is greater than that of the Ka-27PL (3.450 L against 2.940 L). Ka-32 variants, e.g. the Klimov-powered Ka-32A11BC, have been certified for commercial operations throughout the world, notably in Canada and Europe. The Ka-32 has been certified for the newer Klimov VK-2500PS-02 engine. Operational history A Russian Navy Ka-27 helicopter from the Russian Severomorsk conducted interoperability deck landing training on board the US command ship on 22 July 2010. Ka-32A11BC multipurpose helicopters have been successfully operated in Portugal for over five years. In 2006, Kamov won the tender for the supply of Ka-32A11BC firefighting helicopters, to replace Aérospatiale SA 330 Pumas. Over 240 Ka-32 have been built as of 2019 and have been exported to more than 30 countries; South Korea operates some 60 Ka-32s. In the