What was found
ACFT WAS GNDED. ON CLIMB THE CREW REPORTED A BURNING RUBBER ODOR IN THE CABIN. THE CREW DECLARED AN EMER & RETURNED, WHERE THE ACFT LANDED SAFELY WITH NO FURTHER INCIDENTS. PERFORMED TROUBLESHOOTING IAW JC 43L00021001, 43L00072001, & FIM TASK 21-20-00-810-801-A. NO ODORS NOTED, NO ADVERSE CONDITIONS NOTED. OPERATED BOTH PACKS INDIVIDUALLY & TOGETHER WITH ENG 1 - 2, & APU, NO ODORS NOTED AT THIS TIME. UNABLE TO DUPLICATE COMPLAINT. ACFT WAS RETURNED TO SERVICE.