Date: 201306
Local time of day: 0601-1200
Location: ZZZ.Airport, US
Light: Daylight
Aircraft: A320
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Climb
Airspace: Class E ZZZ
ATC / advisory: TRACON ZZZ
Aircraft component: Fuel Line; Fittings; & Connectors
Component problem: Improperly Operated
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Confusion; Distraction; Troubleshooting
Anomaly: Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Flight Crew
When detected: In-flight
Result: Aircraft Aircraft Damaged; Flight Crew Returned To Departure Airport; Flight Crew Landed As Precaution; General Maintenance Action
Contributing factors: Procedure; Human Factors
Primary problem: Human Factors

Narrative: Climbing out of 10;000 FT the aircraft began to vibrate quite a bit. As we climbed out we tried varying the pitch and speed and recycling the landing lights. We found the vibration was speed sensitive. I contacted the A Flight Attendant who stated the forward galley was vibrating; but the most extensive vibration was overwing. We request of ATC to level at 310; we found we had to maintain a speed of .72 or less to keep the vibration under control. We had a current and qualified; A320 Captain; commuting in the cabin. I ask the A Flight Attendant to put him on the interphone. I had the pilot walk the cabin and evaluate the situation. After doing so he came into the flight deck and discussed the problem with us. He had found that the greatest vibration was from overwing to four rows in front of overwing. There was also vibration in the forward galley and flight deck. He felt the problem was either landing lights failed to the down position or an open panel of some type. The First Officer and I had already discussed that the vibration felt like extended lights. After our discussion with the other pilot we also suspected that the fueling bay door might have come open. We attempted to call Dispatch three times using the flight deck in-flight phone. We were the lucky winners of three dropped calls using the flight deck in-flight phone. We ended up talking to dispatch using Commercial Radio. We explained to Dispatch that due to our weight we would be close to an overweight landing if we returned to the departure airport. But we would only be able to maintain .72 if we continued to our destination. The decision was made to return. We got the aircraft turned around and then consulted the Flight Operations Manual as to if we needed to declare an emergency. We felt the situation did not meet the emergency criteria. We elected to go with precautionary landing. I called the A Flight Attendant and told her to prepare for a precautionary landing. I also briefed the passengers about our return to the departure airport. We used approved techniques; lower altitude; gear; speed brakes to increase fuel burn to get the aircraft below maximum landing weight. We landed without further incident. Upon arrival at the gate we had to wait several minutes for a ground crew to marshal us in. After shut down we were told that the aircraft was found to have the fueling bay door open. There was quite a bit of damage to that area of the aircraft. The door had started to separate from the aircraft. I believe the only reason it had not done so was because we had slowed our speed. Part of the door hinge was missing and the electronic wiring inside the fuel bay had been damaged. We deplaned the passengers and had a post incident brief with the flight attendants. I showed them the pictures of the aircraft damage. We change to a different aircraft and continued to the planned destination.




Synopsis: A320 flight crew returned to their departure for a precautionary landing due to an inflight vibration during departure climb.  Post landing aircraft inspection revealed the fueling bay door was open.