to . It replaced steel components with titanium to reduce weight, and had an improved propulsion system. It appeared to have used a similar fire-control system to the P-500, the Argon-KV and Argument radar. The P-1000 was installed on three units of the Northern Fleet between 1987 and 1993. The conversion of two boats of the Pacific Fleet, K-10 and K-34, was abandoned due to lack of funds. The Echo II class were divided evenly between the Pacific and Northern Fleets. The boats were obsolete by the mid-1980s, and were deleted in 1989 and 1995. Ships Accidents Submarines of the Echo class were involved in several accidents : 20 June 1970 K-108 (Echo II) collided with submarine in the Sea of Okhotsk at a depth . The outer hull of K-108 was damaged in the area of compartments VIII and IX, and the sail of Tautog was damaged and the access trunk in it was flooded. There were no fatalities. 14 June 1973 K-56 (Echo II) collided with the Soviet large refrigerating trawler Akademik Berg. The submarine was holed in the bow, and 27 were killed when compartments I and II flooded. 20 August 1973 K-1 (Echo II) struck Hagua Bank () in the Caribbean Sea at a depth of at . The bow was significantly damaged. 28 August 1976 K-22 (Echo II) collided with frigate in the Mediterranean Sea (), and both ships were seriously damaged. K-22 had damage to missile container No. 1, extension devices and the fin structure, and went to Kithira in the Aegean Sea for repairs. The American frigate was damaged at the stern, and had to be towed to Crete. 24 September 1976 K-47 (Echo II) while in the North Atlantic a fire broke out in compartment VIII (living quarters) due to short circuit. Three were killed by carbon monoxide poisoning. 2 July 1979 K-116 (Echo II) suffered a reactor accident (a leak of core coolant from the port reactor) in the Bay of Vladimir, Sea of Japan. Some of the crew received a large dose of radiation, but there were no fatalities. 21 August 1980 K-122 (Echo I) had a fire in compartment VII (turbo-electric) when to the east of Okinawa. Fourteen dead due to carbon monoxide poisoning. 10 September 1981 K-45 (Echo I) collided with Soviet fishing trawler Novokachalinsk at night. The bow of the outer hull and the sonar system of