B747-400
Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 80; Flight Crew Total 21000; Flight Crew Type 800
Troubleshooting; Workload; Distraction
Inflight Event / Encounter Bird / Animal
Aircraft Aircraft Damaged; Flight Crew Landed As Precaution; Flight Crew Returned To Departure Airport; General Maintenance Action
Aircraft; Environment - Non Weather Related
After a normal taxi out and takeoff; a loud deep rumbling noise began as the gear was retracted.  No yaw; vibration or abnormal engine indications were noted except for #1 engine N1 vibration indicator at 5.0.  I reduced Engine 1 to idle and the noise stopped.  When the 'Engine Limit/Surge/Stall' QRC was accomplished and thrust for Engine 1 was advanced and the rumbling noise did not return but 3 compressor stalls were experienced as power approached the climb thrust value.  Engine 1 EGT never moved from the normal range and was operated at idle power for the remainder of the flight.  After consultation with Dispatch and Maintenance; fuel was dumped to achieve max landing gross weight and we returned to the departure airport.  At no time during this sequence did I declare an emergency or ask for emergency equipment to be standing by.  We did receive priority handling by ATC and emergency vehicles were in position as we landed.  The Lead Flight Attendant was advised that no Prep for evacuation was required and that they should follow normal approach and landing procedures.  After parking at the gate; Maintenance observed Engine 1 compressor blade damage and a blood trail in the aft engine area.  No birds were observed during or after takeoff by any of the cockpit crew.
A B747-400 developed a 5.0 engine vibration after takeoff; and after the thrust was reduced then advanced compressor stalls resulted so as a precaution the flight returned to the departure airport. Apparently a bird was ingested during takeoff.