As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
OIL LEAK BY LEFT ENGINE HEAT EXCHANGER OIL FUEL, DURING OVERNIGHT CHECK AT MEX STATION, DUE TO LEFT ENGINE OPERATIONAL TEST, IT WAS DETECTED AN OIL LEAK BY LEFT ENGINE HEAT EXCHANGER OIL FUEL. MAINTENANCE PERSONNEL PERFORMED REVISION, DETECTING AN OIL LEAK BY LEFT ENGINE HEAT EXCHANGER OIL FUEL DURING LEFT ENGINE OPERATIONAL TEST; SO THE HEAT EXCHANGER OIL FUEL WAS REPLACED AND OPERATIONAL TEST WAS PERFORMED IAW AMM 79-21-02, TESTED CORRECT.