As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING HEAVY RAINFALL, AIRCRAFT EXPERIENCED VIBRATION ON MAIN ROTOR SYSTEM. PILOT PERFORMED A PRECAUTIONARY LANDING. MECHANIC INSPECTED THE MAIN ROTOR BLADES AFTER SHUT DOWN. MECHANIC FOUND BOTTOM SIDE OF ONE BLADE 2 INCHES AFT OF LEADING EDGE WITH METAL SKIN DELAMINATED FROM COMPOSITE BLADE.