As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FAIRLY SIGNIFICANT VIBRATION ON THE NR 1 PROPELLER. WHEN POWER LEVERS WERE REDUCED BELOW ABOUT 65%, TORQUE VIBRATION WAS MOST NOTICEABLE. VIBRATION WOULD BECOME LESS NOTICEABLE AFTER SEVERAL SECONDS AND THEN COME BACK WHEN A POWER CHANGE WAS MADE. REMOVED FROM SERVICE. IAW WO 247639 N/R-00001 THROUGH 00004, PROPELLER BALANCING & 6 BLADE RETORQUE ON BOTH PROPELLERS. RETURNED TO SERVICE.