the shape of the exhausts (Mi-8 circular, Mi-17 oval), and C) Dust shields in front of engine air intakes for the Mi-17. Also Mi-17 has some improved armour plating for its crew. The naval Mil Mi-14 version is also derived from the Mi-8. The Mi-8 is constantly improving and the newest version still remains in production in 2016. However the second generation of the Mi-8 was changed to a tractor-tail rotor configuration as this configuration has increased yaw authority from the upwards advancing tail rotor blades into the downwash. The increase of the airspeed flowing over the rotor blades increases overall tail rotor effectiveness and yaw authority, whereas with the 'Pusher' tail rotor configuration the advancing rotor blade moves downwards. This decreases the airspeed across the rotor blade, reducing its overall effective yaw authority. Operational history Finland The Finnish Defence Forces and the Finnish Border Guard began using Mi-8s in the 1970s, with the Finnish Air Force receiving its first, serialed HS-2, on 28 May 1973, and the second, HS-1, on 31 May 1973. Six Mi-8Ts were obtained at first, followed by further two Mi-8Ts and two Mi-8Ps. Three of the helicopters were handed over to the Border Guard Wing. One of these was lost after sinking through ice during a landing in April 1982. It was soon replaced by a new Mi-8. After their Border Guard service, the helicopters were transferred to the civil register, but shortly thereafter to the Finnish Air Force. In 1997 it was decided that all helicopters, including the remaining five Mi-8Ts and two Mi-8Ps, should be transferred to the Army Wing at Utti. All Mi-8s have now been retired. One Mi-8 is on display at the Finnish Aviation Museum in Vantaa, and one is at the Päijänne Tavastia Aviation Museum in Asikkala, near Lahti. The two final Mi-8Ts were given to Hungary in August 2011 with all the remaining spare parts. Georgia The Georgian air force started operating Mi-8 and Mi-17 helicopters from 1991 onwards. During the War in Abkhazia (1992–1993) Mi-8 helicopters were used by both sides. Several were shot down, the first being a Georgian civilian Mi-8T which was destroyed in Sukhumi by an RPG-7. On 14 December 1992, a Russian Air Force Mi-8T was shot down by a SA-14 missile near Lata. On another occasions Abkhaz Mi-8MTVs were shot down by Georgian forces, by SA-14 in one case and by RPG-18