What was found
FLT#479, JFK-MBJ. 'FUME EVENT ON DESCENT, INITIALLY ISOLATED TO PACK 1, ON GROUND W/ PACK 1 OFF & APU BLEED ON, FUME RETURNED WITH PACK 2 ( PACKS ); REF TSI # 501630 FOR RESOLUTION OF DEFECT FOR ODOR EVENT. REMOVED AND REPLACED RECIRCULATION FILTERS REF AMM 21-21-41. NO ODOR OR FUMES ARE PRESENT AT THE MOMENT. PACKS OPS CHECK GOOD REF AMM 21-51-00. MDDR CLEARED. MX-4 UPDATED.'