As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PILOTS REPORTED MAIN ROTOR TRANS CHIP LIGHT AND KNOCKING SOUND. CHECKED CHIP PLUGS AND FOUND DARK GRAY INTERNAL LOOKING METAL ON CHIP DETECTOR. REMOVED MAIN ROTOR TRANSMISSION FROM SERVICE. SENT MAIN ROTOR TRANSMISSION TO NAC IN LONG BEACH. WHEN DISASSEMBLED FOUND BROKEN TOOTH ON OUTPUT RING GEAR, PN 369D25127-11.