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 NOTICED WHEN WE ARRIVED AT AIRCRAFT IN TPA. DISSIPATED WHILE ENROUTE AND CAME BACK STRONGER WHEN WE STARTED DESCENT. SMELL BECAME NOTICEABLY STRONGER DESCENDING THRU FL 250. MAINTENANCE ISOLATED THE SOURCE OF THE ODOR TO THE APU. **SUPPLEMENTAL REPORT WILL BE SUBMITTED** (OPEN)