What was found
NR 3 ENGINE AT 370 FEET, BOTH CHANNEL A AND B 2.7 CAUTION LIGHT ON. SHUTDOWN ENGINE 1200Z. FEELING THE VIBRATION ON THE FLOOR. REMOVED AND INSPECTED MASTER AND INTERNAL GEAR-BOX MAGNETIC CHIP DETECTOR AND OIL FILTERS IAW MM. NO EVIDENCE OF INTERNAL FAILURE. VISUALLY INSPECTED AIR INTAKE, LP COMPRESSOR AND EXHAUST FOR EVIDENCE OF FOD OR DEBRIS, NO EVIDENCE OF DAMAGE. PERFORMED BOROSCOPE INSPECTION. LP ROTOR STAGE 7, HP ROTOR 6 STAGE AND HPT BLADES REAR, NO DAMAGE FOUND. REMOVED AND REPLACED NR 3 ENGINE NR 31 L/P. BLADE IAW MM. PREFORMED VIBRATION SURVEY AND FOUND LEVEL ON NORMAL RANGE IAW MM.