As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
INCORRECT APPLICATION OF LOCKING WASHERS ON ROTOR SHAFT NUT RETAINER LOCK (117-12118-01). INCORRECT APPLICATION OCCURRED DURING INSTALLATION OF REPLACEMENT ROTOR SHAFT. DISCOVERED WHILE PERFORMING MAIN GEARBOX LOWER CASING REPAIR. (REMOVAL OF ROTOR SHAFT REQUIRED). SECURITY OF ROTOR SHAFT RETAINER LOCK IS NOT ASSURED.