What was found
FAINT BURNT RUBBER SMELL COMING THROUGH FO VENT, FA REPORTS SAME SMELL IN FIRST CLASS (FLIGHT #3196 FILED CLOSED) UPON ARRIVAL TALKED WITH FLIGHT CREW AND VERIFIED FAINT SMELL TO COME FROM FO VENT AND MOMENTARILY LASTED A COUPLE OF MINUTES. CYCLED BOTH PACKS OFF AND ON. INSPECTED DUCTING AROUND BOTH PACKS AND IN AVIONICS BAY IN REFERENCE TO AMM 21-51-00 WITH NO DEFECTS NOTED. LET PACKS RUN AND COULD NOT DUPLICATE SMELL IN THE FLIGHT DECK OR THE CABIN. AIRCRAFT OK FOR CONTINUED SERVICE.