United B752 near Gander on Jun 12th 2014, electrical heating blanket melts plastics

A United Boeing 757-200, registration N12109 performing flight UA-152 from Newark,NJ (USA) to Stuttgart (Germany), was enroute at FL350 near Gander,NL (Canada) about 2 hours into the flight when a passenger reported a panel on the sidewall besides his seat had become uncomfortably hot. The flight attendant checked the panel, then moved the passengers in that seat row out of their seats into other seats. The first officer checked the panels attempting to remove the panels without success and returned to the cockpit, the captain subsequently checked the panels thoroughly, feeling the various hot spots and checking consistency and discolouration of the plastics, then indicated he would consult with maintenance. A short time later the crew radioed Gander Area Control that they needed to return to Newark due to an electrical heating blanket around a door melting plastics. On the way back passengers noticed that cabin lighting and inflight entertainment system were shut down. The aircraft turned around and returned to Newark for a safe landing about 160 minutes after turning around.

A passenger reported the crew announced that there was a problem in the area of the first emergency door at the right hand door explaining that there is a heating element behind the side wall to keep the area of the emergency exit comfortable. There was a possibility that the temperature controller of that heating element had failed causing the element to overheat. The captain felt it was safer to return to Newark than to continue with the Atlantic crossing with the door situation. Flight attendants subsequently checked the panel every 15 minutes until landing in Newark.

The flight was cancelled, the passengers were rebooked onto other flights.

The side panel and the hottest discoloured spot: