B767 Undifferentiated or Other Model
Flight Crew Last 90 Days 120; Flight Crew Total 18500; Flight Crew Type 150
Aircraft Equipment Problem Critical
Flight Crew Landed in Emergency Condition; Flight Crew Returned To Departure Airport; General Declared Emergency; General Maintenance Action
Aircraft
Shortly after takeoff the purser called the cockpit to report a significant vibration under the floor of the cabin from mid wing area and extending forward to the First Class Cabin. We contacted Dispatch and Maintenance Control to get them in the loop. After some troubleshooting that did not resolve the problem; we elected to return to the departure field. An emergency was declared with ATC. We dumped approximately 40;000 LBS of fuel and landed approximately 16;000 LBS over maximum landing weight.
During the initial climb the flight attendants notified the cockpit that unusually loud noises and a thumping noise with a great deal of vibration was heard in the cabin of the aircraft. They described the noises and vibration as something they have never encountered before. The Relief Pilot was sent back to the cabin and he also confirmed that the noises and vibrations were abnormal. The landing gear was cycled and had no effect on the noises and vibrations. The Captain called Dispatch and Maintenance Control to help with the problems as I flew the aircraft; handled ATC; and maintained situational awareness. No fixes or determination of what was causing the vibrations and noises were able to be made. The decision was made to return to the departure field. ATC was advised of our intent to return; that we will be dumping fuel; and declaration as an emergency aircraft. Fuel dumping was performed as per the Flight Manual. Dispatch helped in coordinating the return; overweight landing and landing data. Maintenance Control handled the logging of the defect as per his request. The approach and landing was uneventful and smooth. After landing the emergency vehicles observed and reported nothing out of the ordinary with the aircraft. We taxied to the gate and secured the aircraft; made sure the passengers and flight attendants were being taken care of and then we debriefed the awaiting mechanics. The vibrations and noises occurred throughout the entire flight.
The pilots of a B767 were advised by the flight attendants of an odd noise and vibration in the cabin floor. After reviewing the problem with the company Dispatch and Maintenance Control personnel; the crew determined that returning to the field was the best course of action. They declared an emergency; dumped fuel and performed a successful landing slightly over weight.