The ATSB final investigation report into the crash that killed the two occupants of a Robinson R22 helicopter at Yakka Munga Station in Western Australia, has found that a drive shaft to the main rotor blades failed.
Examination of the shaft revealed that it had failed as a result of a fatigue crack that initiated at a bolt hole in the shaft. Inappropriate procedures, including use of an unapproved sealant, were used when the shaft was last assembled.
During the investigation, the ATSB issued an urgent safety recommendation to the Civil Aviation Safety Authority (CASA) asking for an…