As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED: FUME SMELL FORWARD AND AFT CABIN ABOUT 40 MINUTES INTO FLIGHT ON DESCENT. MAINTENANCE REPLACED THE APU GEARBOX VENT LINE DUE TO EVIDENCE OF COKING ((AALA202511117382) AND REPLACED THE APU GEARBOX AIR OIL SEPARATOR (AALA202511117922) PER TASK CARD 26L00021002. A DECONTAMINATION OF THE ENVIRONMENTAL CONTROL SYSTEM PER TASK CARD 26L00021014 WAS ACCOMPLISHED WITH NO LEAKS OR ODORS NOTED.