Future Helicopter Strategy including the purchase of twenty-four new build Chinooks, twenty-two to expand the force and two to replace losses in Afghanistan, to be delivered to the RAF from 2012. The number of additional Chinooks was cut by twelve in the Strategic Defence and Security Review 2010. This brought the total fleet size to sixty aircraft; as of 2009, the RAF had forty-eight Chinooks in inventory. Northern Mali In July 2018, three RAF Chinook helicopters were deployed to assist French forces in the Northern Mali conflict with logistics and troop movement. Variants Chinook HC1 New-build aircraft for the RAF based on the CH-47C, forty-one built. Chinook HC1B Modification of the forty-one HC1s with metal rotor blades, survivors converted to HC2. Chinook HC2 Conversion by Boeing of thirty-two surviving HC1Bs to CH-47D standard, and three new build-aircraft Chinook HC2A Similar to the HC2 with strengthened fuselage using milled structure manufacturing techniques, six built. Chinook HC3 Special forces variant based on the CH-47SD, eight built. Chinook HC4 HC2/2A aircraft with upgraded engines and avionics under Project Julius. forty-six conversions planned. Chinook HC5 HC3 aircraft with upgraded avionics under Project Julius and the replacement of the analogue flight control systems with the Boeing Digital Automatic Flight Control System (DAFCS). Chinook HC6 New-build Chinooks announced in 2009, originally twenty-four aircraft, later reduced to fourteen (twelve new helicopters plus two attrition replacements). The final aircraft were delivered in December 2015. Chinook HC6A Upgrade of the HC4 Chinooks, with the replacement of the analogue flight control systems with the Boeing Digital Automatic Flight Control System (DAFCS). Operators RAF Odiham No. 7 Squadron – Part of the Joint Special Forces Aviation Wing No. 18(B) Squadron No. 27 Squadron No. 240 Operational Conversion Unit RAF – Joint Chinook and Puma HC1 Operational Conversion Unit, 1980 to 1993 RAF Benson No. 28 Squadron – Joint Chinook and Puma HC2 Operational Conversion Unit, 2015 onwards Notable incidents and accidents 13 May 1986 Chinook HC1 ZA715 crashed in bad weather in the Falkland Islands. The helicopter, with four crew and twelve troops, crashed into a hill four miles from its destination. With rescuers hampered by blizzards, the personnel were recovered but one crew member had died shortly after the crash, and the co-pilot and a soldier died on the way to hospital. The board of inquiry concluded that the crew had become disorientated due to "white-out" conditions. 27 February 1987