As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) REDUCTION GEARBOX CHIP DETECTED FAULT CODE (939) WAS RECEIVED THROUGH THE FAST SYSTEM. DUE TO PREVIOUS HISTORY, THE AIRCRAFT RETURNED TO THE GATE AND WAS REMOVED FROM SERVICE FOR AN ENGINE CHANGE. THE ENGINE WILL BE ROUTED TO THE MANUFACTURER FOR INVESTIGATION.