What was found
SMOKE APPEARED IN THE COCKPIT AND CABIN DURING CLIMB-OUT OF EWR. THE AIRCRAFT WAS RETURNED TO EWR WHERE IT LANDED WITHOUT INCIDENT. A BOROSCOPE INSPECTION OF THE NR 1 ENGINE HPC 1ST, 2ND, AND 3RD STAGES FOUND EVIDENCE OF OIL LEAK IN ALL STAGES. THE NR 1 ENGINE WAS REMOVED AND REPLACED. THE ENGINE WAS RUN AT TAKEOFF POWER WITH NO SMOKE OR DEFECTS NOTED. ENGINEERING INVESTIGATION REVEALED THE NR 3 BEARING STATIONARY AFT AIR/OIL SEAL HAD BROKEN INTO THREE PIECES AND WAS THE PRIMARY CAUSE OF ENGINE OIL LEAK.