As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED: DURING DESCENT AT IDLE POWER STRONG OILY SMELL AT COCKPIT AND AFT CABIN BELOW 10,000" ISOLATED SOURCE OF ODOR TO THE APU DUE TO FINDING OIL IN THE APU INLET OPENING. REPLACED APU OIL COOLER AND APU OIL COOLING FAN (AALA202111101776) PER AMM 49-91-44. A SATISFACTORY LEAK / OPERATIONAL CHECK WAS ACCOMPLISHED.