As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
BURNING RUBBER SMELL AT ROW 30. TURNED OFF UTILITY BUSSES RECIRC FANS CARGO HEAT. SMELL DISSIPATED. INSPECTED AREA ALL AROUND ROW 30. TURNED ON ALL IFE OVENS/COFFEE MAKERS/RAN APU AND PACKS. RAN ENGS AND PACKS. INSPECTED GASPER FAN AREA AND RECIRC FANS. NO PROBLEMS OR ODORS. COULD NOT DUPLICATE. REPLACED L/R RECIRC FANS AND GASPER FAN. PERFORMED NON REV VERIFICATION FLT.