As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING PREFLIGHT OIL WAS NOTICED ON THE UPPER TRANSMISSION CASE. UPON FURTHER INVESTIGATION, PAINT WAS BUBBLED ON RING GEAR CASE. CLEANED PAINT & DYE PENETRANT WAS USED REVEALING A SUSPECTED CRACK. ACFT WAS RUN AT 100% NR & OIL WAS NOTICED COMING FROM A CRACK IN THE TRANSMISSION RING GEAR CASE.