What was found
ON TAKEOFF RWY 25L VHHH, AFTER POWER REDUCTION TO CLIMB AT 1500 AFL, GOT A YAW "BUMP" AND NOISE AND VIBRATION "BUZZ" IN AIRFRAME. NO ABNORMAL INDICATIONS INITIALLY, THEN NR 1 COMPRESSOR VIBRATION CLIMBED TO 5.0 AMBER, REDUCED NR 1 THROTTLE AND BUZZ DIMINISHED. NOISE QUIET AND INDICATION NORMAL AT IDLE, LEFT ENGINE RUNNING FOR SYSTEMS AVAILABILITY, DUMPED 147,000 POUNDS FUEL, LANDING VHHH.