MI-8T RA-24267 17.10.2012

      The Interstate Aviation Committee Investigation team has completed the investigation of the accident with Mi-8Т RA-24267 helicopter owned by "Kras Avia" state enterprise occurred in the Krasnoyarsk Territory (RF) on October 17, 2012. 
      The accident with Mi-8Т RA-24267 helicopter was caused by helicopter handling in yaw loss occured at the landing phase in snow whirl conditions due to antoitorque rotor entering vortex-ring state resulted in helicopter backing, ground impact outside landing zone and helicopter starboard roll-over.
      Helicopter uncoltrolled rotation is not connected with rotorcraft status. Helicopter control was in normal, operational status prior to emergency situation.
      Uncontrolled helicopter rotation was caused by:
      - wrong perception of helicopter attitude by PIC in relation to landing place linear reference point (coaming) resulted in helicopter airfield overshoot on ground fill followed by wheel mush and right roll; 
      - further uncoordinated controls actions by PIC resulted in rotor speed drop below allowable limits and rotational speed increase.
      Contributing factors were:
      - untimely PIC's decision about go aroung flight maneuver in snow whirl conditions;
      - failures in crew members actions and coordination during landing in snow whirl conditions;
      - WS authorization for flights is carried out with deviation from Flight Crew Training Program requirements at Мi-8Т, Мi-8АМТ helicopters;
      - lack of the appropriate monitoring for formed crew operation from command and flight crew of the enterprise;
      - inadequate preparation of landing zone, lack of monitoring for its status from owner of the landing zone;
      - lack of specific recommendations in Mi-8 FOM on crew actions in uncontrollable spin not connected with aviation equipment failures during hovering and flight phases close to hover mode.
      Most probably the passenger fatality is connected with long-range tank separation from mooring, fatal injuries caused by it that resulted in lack of monitoring procedure for long-range tank mooring installed in helicopter cargo hold.
      Appropriate safety recommendations based on the investigation results were developed.