What was found
AIRCRAFT WAS GROUNDED: DURING DESCENT PASSING 13,000 FT, HAD A MILD ODOR OF DIRTY SOCKS. LASTED APPROXIMATELY 1 MINUTE. ODOR WAS CONTAINED TO THE COCKPIT AND FORWARD GALLEY. MAINTENANCE ACCOMPLISHED JOB CARD 26L00021001 SMOKE / ODOR / FUME TROUBLSHOOTING AND FOUND THE RECIRCULATION FILTERS TO BE THE SOURCE OF THE ODOR AND REPLACED THEM PER AMM 21-21-41. A SATISFACTORY OPERATIONAL CHECK WAS ACCOMPLISHED WITH NO ODORS NOTED.