Primary finding
Probable cause
An in-flight main rotor blade spar separation as a result of the pilot-in-command's decision to continue to fly the aircraft after it had failed an AD directed BIM check. Factors were the failure of the operator's chief pilot to maintain proper supervision over the operation of a company aircraft with a known grounding deficiency and the improper repair to the main rotor blade by unknown persons, which damaged the blade's spar.