were damaged, of which only two were ever repaired. The 19-year old sailor responsible admitted to starting the fire. At his court martial he was found to have not been responsible for his actions due to mental illness. S-2G Tracker The RAN was able to rapidly rebuild its Tracker fleet. An order for six ex-US Navy S-2G Trackers had been placed in October 1976 to modernise the force. This order was increased to sixteen S-2Gs soon after the fire. The US Government sold the aircraft at a discount of 97 percent of their value, and allowed a RAN team to select airframes from US Navy stores shortly after the order was placed. The US Navy also donated spare parts to Australia. The aircraft were refurbished and then flown to San Diego, where in March 1977 they were loaded onto Melbourne. The aircraft entered service shortly afterwards. The S-2Gs' performance and features were similar to the S-2Es. Their sonic systems were upgraded during 1977 and 1978 to enable the use of more advanced sonobuoys. In 1978 Hawker de Havilland approached the Navy with a proposal to upgrade several of the Trackers' surveillance systems at a cost of between $1 and $1.5 million per aircraft. This proposal was rejected. In mid-1977 Melbourne travelled to the United Kingdom with 816 Squadron aircraft embarked to participate in a fleet review organised to mark the Silver Jubilee of Elizabeth II. The ageing carrier took part in regular training exercises for the rest of the 1970s. Following an accident on 21 October 1980 in which a Skyhawk was destroyed due to a malfunction in Melbournes catapult, Trackers were the only fixed-wing aircraft to operate from the carrier for the remainder of its career. In June 1981 a Tracker operating from Melbourne in the South China Sea spotted a boat carrying 99 Vietnamese refugees. The carrier rescued all of the refugees. From November 1977 land-based Tracker patrols were expanded. The detachment at Darwin began conducting patrols to locate boats carrying refugees escaping from Vietnam. In 1980, the type also began to be used for anti-terrorism patrols around oil rigs in the Bass Strait. The later task continued until 31 December 1983. Melbourne completed its final deployment in November 1981, and was decommissioned in June the next year. 816 Squadron was merged into 851 Squadron on 2 July 1982. 851 Squadron continued to use Trackers for maritime patrol