As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED: ON DEPARTURE AT 8000', FLIGHT ATTENDANT CALLED THE COCKPIT TO REPORT THAT TWO OF THEM SMELLED A STRONG "RANCID SOUR" ODOR IN THE BACK OF THE AIRPLANE FROM ABOUT ROW 25 AFT. DECESION MADE TO RETURN TO CLT. MAINTENANCE ACCOMPLISHED J/C 26L00021001- NO FAULT FOUND. DURING ENGINE RUN ISOLATION NO ABNORMAL SMELL/TASTE DETECTEDIN COCKPIT NOR CABIN. A/C OK FOR SERVICE.