What was found
CREW REPORTED DURING THE LAST 5 MINUTES OF CRUISE FLIGHT, THERE WAS AN OCCASIONAL SMELL OF BURNING RUBBER IN THE FLGHT DECK. SMELL WOULD NOT DISSIPATE AND WOULD RE-APPEAR. SMELL BECAME MUCH STRONGER ON FINAL APPROACH. DURNING TAXI-IN, TURNED OFF LEFT PACK AND SMELL DISSIPATED. TURNED LEFT PACK BACK ON AND SMELL RE-APPEARED. MAINTENANCE ACCOMPLISHED T/S JOB CARD 03L000021001 AND 03L00036001. REPLACED RECIRCULATION HEPA FILTER IAW AMM 21-21-23. RAN ENGINES WITH LEFT PACK. NO ODOR AT THIS TIME.