As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) PILOT HAD AN TGB CHIP LIGHT INFLIGHT. LANDED AT HIS BASE FOR THE ENGINEER TO CHECK IT OUT. THEY FOUND A LOT OF A DARK GRAY SLUDGY SUBSTANCE WHICH PUT THE CHIP LIGHT ON. THEY DRAINED THE GEARBOX ANDDID A GROUND RUN FOR ABOUT .5 HOUR AND FOUND NOTHING (NO METAL). WE REPLACED THE GEARBOX WITH A NEW OVERHAULED ONE AND SENT THIS GEARBOX FOR REPAIR OR OVERHAUL.