Narrative:

On initial climb we noticed an unusual rattling noise from the outside of the aircraft. We elected to make a precautionary landing at the departure airport; staying in the pattern and landing without incident. No emergency was declared and we remained on the CTAF frequency throughout the return for landing. Upon inspection of the exterior of the aircraft; we found the person that had fueled the airplane securing the fuel cap and closing the fuel door. He must have seen us return and realizing he had not secured the cap after fueling and came to see about it as we taxied in. The cap had scuffed and chipped the paint on the fuselage and left some small dents and nicks on the leading edge and inboard root section of the wing. My first officer and I both had failed to do a final walk around the aircraft before finally closing the passenger door for flight.I was at the aircraft for the fueling process; but I was inside the cabin when it was happening. I should have been standing by the fueling person to monitor his actions. That way I would have been able [to] confirm the fueling hose removed; the cap replaced; and the fuel door latched. Of course; I and my partner both should have obeyed company procedures and done one last look around the plane before closing the passenger door for the last time prior to engine start.

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Original NASA ASRS Text

Title: Cessna CL560 crew heard an unusual noise after take-off and returned to departure airport to find the fuel door unlatched.

Narrative: On initial climb we noticed an unusual rattling noise from the outside of the aircraft. We elected to make a precautionary landing at the departure airport; staying in the pattern and landing without incident. No emergency was declared and we remained on the CTAF frequency throughout the return for landing. Upon inspection of the exterior of the aircraft; we found the person that had fueled the airplane securing the fuel cap and closing the fuel door. He must have seen us return and realizing he had not secured the cap after fueling and came to see about it as we taxied in. The cap had scuffed and chipped the paint on the fuselage and left some small dents and nicks on the leading edge and inboard root section of the wing. My FO and I both had failed to do a final walk around the aircraft before finally closing the passenger door for flight.I was at the aircraft for the fueling process; but I was inside the cabin when it was happening. I should have been standing by the fueling person to monitor his actions. That way I would have been able [to] confirm the fueling hose removed; the cap replaced; and the fuel door latched. Of course; I and my partner both should have obeyed company procedures and done one last look around the plane before closing the passenger door for the last time prior to engine start.

Data retrieved from NASA's ASRS site as of July 2013 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.