As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED: MUSTY SMELL THROUGHOUT CABIN, PARTICULARLY DURING DECENT AND LANDING. MAINTENANCE HAS ISOLATED THE SOURCE OF THE ODOR TO THE APU. REPLACED APU AND ACCOMPLISHED A SATISFACTORY LEAK / OPERATIONAL CHECK PER TASK CARD 26L31049003.