What was found
AFTER TAKEOFF AT 500 FEET ENGINE NR 1 EXPERIENCED SEVERE VIBRATION. THRUST WAS REDUCED AND VIBRATION DECREASED. ENGINE NR 1 OIL LOSS WAS THEN NOTICED AND ENGINE NR 1 WAS SHUTDOWN. FLIGHT CREW RETURNED AIRCRAFT TO DEPARTURE AIRPORT AND PERFORMED AN UNEVENTFUL LANDING. MAINTENANCE FOUND FOUR DAMAGED FAN BLADES DUE TO A BIRD STRIKE AND THE OIL OUT LINE OF THE FUEL/OIL HEAT EXCHANGER LOOSE. ENGINE BORESCOPE INSPECTION CHECKED GOOD. REPLACED 8 FAN BLADES, TIGHTENED OIL COOLER LINE AND PERFORMED ENGINE NR 1 RUNUP, VIBRATION LEVELS IN LIMIT.