Narrative:

Shortly after takeoff the cabin called. We picked up the phone and no one was there. As we approached approximately 7000 ft we were called again. This time the lead flight attendant was there and he reported that there were sparks flying out of the ceiling adjacent the door 3L. There was an electrical smell, smoke and loud popping noises coming from the PA system. The lights were flashing on and off. When the lights were on, they were several times their normal brightness. Flight attendant took 2 fire extinguishers and discharged them into the space above door 3L where the sparks were coming from. After assessing the situation, I made the decision to return to ZZZ. We ran the 'smoke, fumes and electircal' checklist and coordinated quick return with the tower and the flight attendants. We had the fire equipment standing by. We dumped 18500 pounds of fuel and proceeded direct to the FAF for runway. We secured from dumping at 1000 ft. After landing we considered an emergency evacuate/evacuation but since the sparks and smoke had ceased, we proceeded to the gate. We had the fire trucks follow us to the gate.

Related reports:

Google
 

Original NASA ASRS Text

Title: A B767 FLT ATTENDANT ALERTS THE FLT CREW JUST AFTER TKOF THAT THERE WERE SPARKS AND FUMES COMING FROM THE CABIN LIGHTING. THE FLT CREW RETURNED TO ZZZ FOR AN EMER LNDG.

Narrative: SHORTLY AFTER TKOF THE CABIN CALLED. WE PICKED UP THE PHONE AND NO ONE WAS THERE. AS WE APCHED APPROX 7000 FT WE WERE CALLED AGAIN. THIS TIME THE LEAD FLT ATTENDANT WAS THERE AND HE RPTED THAT THERE WERE SPARKS FLYING OUT OF THE CEILING ADJACENT THE DOOR 3L. THERE WAS AN ELECTRICAL SMELL, SMOKE AND LOUD POPPING NOISES COMING FROM THE PA SYS. THE LIGHTS WERE FLASHING ON AND OFF. WHEN THE LIGHTS WERE ON, THEY WERE SEVERAL TIMES THEIR NORMAL BRIGHTNESS. FLT ATTENDANT TOOK 2 FIRE EXTINGUISHERS AND DISCHARGED THEM INTO THE SPACE ABOVE DOOR 3L WHERE THE SPARKS WERE COMING FROM. AFTER ASSESSING THE SIT, I MADE THE DECISION TO RETURN TO ZZZ. WE RAN THE 'SMOKE, FUMES AND ELECTIRCAL' CHKLIST AND COORDINATED QUICK RETURN WITH THE TWR AND THE FLT ATTENDANTS. WE HAD THE FIRE EQUIP STANDING BY. WE DUMPED 18500 LBS OF FUEL AND PROCEEDED DIRECT TO THE FAF FOR RWY. WE SECURED FROM DUMPING AT 1000 FT. AFTER LNDG WE CONSIDERED AN EMER EVAC BUT SINCE THE SPARKS AND SMOKE HAD CEASED, WE PROCEEDED TO THE GATE. WE HAD THE FIRE TRUCKS FOLLOW US TO THE GATE.

Data retrieved from NASA's ASRS site as of July 2007 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.