As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED: ON ARRIVAL AT 7700' 32 MIN FROM CLT SUDDEN ONSET OF STRONG DIRTY SOCK SMELL. FLIGHT CREW DONNED O2 MASKS WHILE CABIN CREW DID NOT SMELL ANY ODOR. MAINTENANCE FOUND THE APU OIL COOLER (AALA202309290473) AND THE APU OIL COOLING FAN (AALA202309296227) LEAKING OIL. MAINTENANCE REPLACED THE APU OIL COOLER PER AMM 49-91-44 AND REPLACED THE APU OIL COOLING FAN PER AMM 49-52-51. A SATISFACTORY LEAK / OPERATIONAL CHECK WAS ACCOMPLISHED.