|Aircraft registration number||RA-31579|
|Place of aircraft departure|
|Airport of departure|
|Intended Airport of arrival|
|Accident site||в районе г. Сочи|
|Aircraft owner||ОАО НПК «ПАНХ»|
|The date of the completion of the investigation (report)|
|Number of fatalities||0|
|Degree of aircraft destruction|
The Investigation team of the Interstate Aviation Committee has completed the investigation of the accident with Ka-32AO RA-31579 helicopter owned by "PANH Helicopters" JSC occurred in the Krasnodar region on July 26, 2012.
The accident with КА-32АО RA-31579 helicopter was caused by right engine № 7087893000127 failure during suspended load installation on high airfield that resulted in dynamic rotor speed decay and the need of emergency landing on unprepared airfield with increased rate of descent followed by aircraft separation fr om ground and rightward turnover.
The engine failure was caused by rotating blades destruction of the I compressor turbine stage followed by the damage of rotating blades and nozzle diaphragms of the following turbine stages.
The destruction of the engine kompressor turbine blades in conditions of its long-term operation at high-heat modes under high temperatures of the maritime climate open air and middle altitude was caused by the material lim it behaviour and accumulated damage in it is most probably in a form of sulphide corrosion.
Sulphide corrosion pitting most probably was caused by:
• using of separate foreign fuel deliveries having increased fuel sulfur, aromatic hydrocarbons and resin content compared to domestic fuel types as well as the lack of aircraft engine operation best practice using foreign fuel in order to take appropriate mesures;
• operational performance of termocouples not ensuring their operability during design service life of TB3-117 engines;
• increased gases temperature in front of the compressor turbine due to operability violation of almost the half of thermocouples of the gases temperature limitation system in front of the turbine;
• lack ofCHK-78-1 elapsed time counters and counters-control at Ka-32AO RA-31579 helicopter as well as gases temperature recording in front of the turbine by aircraft recorder that didn't allow to regard engines life with adequate accuracy.
The appropriate safety recommendations based on the investigation results were presented