What was found
OIL SMELL PERMEATED THE ENTIRE CABIN AND COCKPIT DURING DESCENT. *S/D* FOUND OIL RESIDUE ON NR 1 ACM. REPLACED ACM, NO OIL LEAKS FOUND. INVESTIGATION REVEALED ACM INGESTED FOD, NO DAMAGE FOUND, THE OIL SEALS WERE INTACT. A 2ND ACM WAS REMOVED, DISASSEMBLED AND TESTED, NO LEAKS FOUND. ACM'S WERE NOT THE CAUSE OF THE SMELL. NR 2 MAIN ENGINE WAS REPLACED ON 5/2. AFTER THE REPLACEMENT OF 2 ACMS, 2 PACK BURNOUTS, SMELL STILL EXISTED. AFTER NR 2 ENGINE REPLACEMENT THE OIL SMELL DISAPPEARED. THE NR 2 ENGINE WAS LIKELY THE CAUSE OF THE OIL SMELL.