What was found
AIRCRAFT WAS GROUNDED: FLIGHT ATTENDANTS REPORTED A FUME EVENT APPROXIMATELY 10 MINUTES AFTER TAKE OFF. APU HAD BEEN OFF FOR APPROX. 20 MINUTES. WE RAN THE FUME CHECKLIST WHICH SEEMED TO HELP DISSIPATE THE FUMES. FUMES WERE WORST IN THE BACK, SMELL DESCRIBED AS SOLID AND DIRTY SOCKS. AN EMERGENCY WAS DECLARED AND THE AIRCRAFT LANDED SAFELY AT DFW WHICH WAS THE SCHEDULED DESTINATION. MAINTENANCE ACCOMPLISHED SMOKE ODOR FUMES TROUBLE SHOOTING TASK CARD 26L00021001 WITH NO DEFECTS OR ODORS NOTED, RAN ENGINES FOR 30 MINUTES ABOVE IDLE WITH NO DEFECTS OR ODORS NOTED. ODOR COULD NOT BE DUPLICATED AND AIRCRAFT WAS RETURNED TO SERVICE.