Russian Helicopters is proceeding with the development of the Mi-38 heavy twin, and the fourth prototype recently made its maiden flight. This latest iteration of the helicopter differs from the third prototype, which first flew in November 2013, in its shock-resistant fuel system and larger windows. Klimov TV7-117V turboshaft engines–2,800 shp each at takeoff–power the 34,400-pound rotorcraft, which has a passenger capacity of 30.