Ми-8 МТВ1 RA-25560 29.08.2011

      The Interstate Aviation Committee Investigation team has completed the investigation of the accident with Mi-8MTB-1 RA-25560 helicopter oned by "PANH Helicopters" JSC occurred in Arkhiz locality of the Karachayevo-Cherkassian Republic on August 29, 2011. 
      The crash with Mi-8МТВ-1 RA-25560 helicopter was caused by inability of safe operation (landing or go-around flight manoeuver) under effective flight case (altitude, speed, open air temperature, helicopter flying weight, landing place performance) which were not beyond specified FOM limitations due to inadverent engine power reduction after its coming to takeoff power before hovering above landing place that resulted in helicopter abrupt descent, ground impact and rotorcraft structure damage.
      Right engine power reduction was caused by incapacitation of ЭРД-3ВМ series 2 № 06882074 electronic engine control due to failure of 580ВВ55 integrated circuit at micro board 8Т5.103.093 № 082.08.04.
      Failure of chip board 580ВВ55 series 0711 was caused by destruction of welded joint of conductor № 22 with beam contact plate due to poor ultrasonic welding.
      This manufactured flaw most probably was caused by violation of technology and quality inspection during chip production.
      The appropriate safety recommendations based on the investigsation results were developed.