Narrative:

I operated flight. The inbound crew had one entry into the maintenance log related to a burning smell in the aft galley. Contract maintenance reviewed the log and inspected the aft galley. Their inspection found no evidence of anything that had been burning. In discussion with maintenance service it was decided to placard both chillers; all coffee makers and turn off all related galley equipment. The following was completed and we departed. Around 40 minutes into the flight and after leveling off at FL380; the flight attendants called the cockpit to inform us that a burning smell had returned to the galley. We turned off the utility busses; removing all power to the galleys. This did not reduce the burning smell. The smell was strong enough that a non-revenue flight attendant and her husband could smell it in the last row of coach along with some other passengers. (I was not informed of this fact until after the flight). I elected to send the first officer to the aft galley to see if we needed to divert. At the same time; we were in contact with dispatch and maintenance in an effort to resolve the issue. My first officer returned to the cockpit and said something was causing a strong electrical smell in the aft galley. At that point; I made the decision to divert. At the same time; we were asked by maintenance to pull the P19 circuit breaker for the cooling fan in the aft galley. This did not resolve any of the burning smell. As we joined approach control and the smell was not dissipating after removing all the power and pulling the circuit breakers; I elected to declare an emergency. The landing was normal and we taxied to the gate. Maintenance then began inspecting the aircraft. As in our departure station; the smell was not present on the ground. After 4 hours of inspecting; the maintenance team came forward and showed me melted insulation that was wrapped around the cold water pipes. They also showed me an electrical box that was not grounded correctly. At this point; their theory was the electrical box had made contact with the pipe conducting electricity via the pipes burning/melting the insulation and resulting in the burning smell in the galley.

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Original NASA ASRS Text

Title: A B767 diverted to an enroute airport after a strong burning electrical smell in the aft galley persisted with power removed from the cabin. Mechanics found an improperly grounded electrical box shorting to a water pipe and burning the insulation.

Narrative: I operated flight. The inbound crew had one entry into the maintenance log related to a burning smell in the aft galley. Contract Maintenance reviewed the log and inspected the aft galley. Their inspection found no evidence of anything that had been burning. In discussion with Maintenance Service it was decided to placard both chillers; all coffee makers and turn off all related galley equipment. The following was completed and we departed. Around 40 minutes into the flight and after leveling off at FL380; the flight attendants called the cockpit to inform us that a burning smell had returned to the galley. We turned off the utility busses; removing all power to the galleys. This did not reduce the burning smell. The smell was strong enough that a non-revenue Flight Attendant and her husband could smell it in the last row of coach along with some other passengers. (I was not informed of this fact until after the flight). I elected to send the First Officer to the aft galley to see if we needed to divert. At the same time; we were in contact with Dispatch and Maintenance in an effort to resolve the issue. My First Officer returned to the cockpit and said something was causing a strong electrical smell in the aft galley. At that point; I made the decision to divert. At the same time; we were asked by Maintenance to pull the P19 circuit breaker for the cooling fan in the aft galley. This did not resolve any of the burning smell. As we joined Approach Control and the smell was not dissipating after removing all the power and pulling the circuit breakers; I elected to declare an emergency. The landing was normal and we taxied to the gate. Maintenance then began inspecting the aircraft. As in our departure station; the smell was not present on the ground. After 4 hours of inspecting; the maintenance team came forward and showed me melted insulation that was wrapped around the cold water pipes. They also showed me an electrical box that was not grounded correctly. At this point; their theory was the electrical box had made contact with the pipe conducting electricity via the pipes burning/melting the insulation and resulting in the burning smell in the galley.

Data retrieved from NASA's ASRS site as of April 2012 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.