The Mil Mi-10 (NATO reporting name Harke), given the product number izdeliye 60, is a Soviet military transport helicopter of flying crane configuration, developed from the Mi-6, entering service in 1963. While most versions had been retired by 2009, the short-legged Mi-10K was still in service as of 2014. Design and development The advent of the Mi-6 gave the Soviet Union the very useful ability to move and place large, bulky or heavy loads with precision. Limitations of the Mi-6 in the flying crane role included a weight to payload ratio and the inability of the crew to easily see the load and its intended final position. A Council of Ministers directive of 20 February 1958 tasked OKB-329 (OKB Mil) with the development of a dedicated flying crane helicopter for carrying bulky loads unable to be carried in the hold of an Mi-6. The Mil OKB's response drew heavily on the Mi-6, utilising the dynamic components and Soloviev D-25V turboshaft engines, on a slim fuselage sitting on four tall strut braced undercarriage legs, with a wide track allowing the helicopter to taxi over loads, or for mobile loads to be moved underneath. The fuselage can carry 28 passengers inside the cabin as well as of cargo loaded through a side door in the aft fuselage, by an integral boom and winch. Underslung loads can be attached directly to the fuselage by hydraulically operated clamps, or carried on a pallet lifted by the winch and braced by cables and/or struts to the undercarriage legs. The external sling system of the Mi-6, with a capacity of could also be fitted under the centre fuselage. The first prototype V-10 emerged with canted main undercarriage legs with single wheels on all four legs, as well as a retractable emergency escape chute extending below the cockpit and external auxiliary fuel tanks either side of the centre fuselage. As development progressed the main undercarriage legs were replaced with vertical units carrying twin wheels, twin nose undercarriage wheels after a period retaining the single wheels, an auxiliary power unit (APU) installed behind the cockpit on the starboard side and emergency escape slide cables for use when the pallet is carried. The first prototype V-10 was completed in 1959 and was soon officially allocated the service designation Mi-10. The first flight took place on 15 June 1960 and flight testing continued successfully until in May 1960 the first