What was found
AIRCRAFT WAS GROUNDED, DURING FINAL APPROACH, WITH GEAR DOWN, BOTH PACKS ON, & APU OFF. THERE WAS A STRONG ODOR OF DIRTY SOCKS. AFTER LANDING WITH PACKS OFF THE ODOR DISSAPATED. MAINTENANCE ISOLATED THE SOURCE OF THE ODOR TO THE APU DUE TO FINDING EVIDENCE OF OIL IN THE APU INTAKE AND FULL EXTERIOR OF THE APU AREA. MAINTENANCE REPLACED THE APU IAW TASK CARD 26L31049003.