As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING AIRCRAFT RUN-UP, ROTOR TACHOMETER WENT TO ZERO. FOUND ONE TOOTH ON RING GEAR CHIPPED. FOUND CHIP JAMMED IN OIL PUMP GEARS WHICH CAUSED OIL PUMP DRIVESHAFT TO SHEAR. SCHWEIZER SB 244.2 ADDRESSES THIS SUBJECT. THIS IS ALSO ADDRESSED IN THE 50/100 HR CHECK LIST. TRANSMISSION REMOVED AND REPLACED WITH OVERHAULED UNIT.