Westjet B738 near Thunder Bay on Oct 21st 2014, soap ain't insulating

A Westjet Boeing 737-800, registration C-FRWA performing flight WS-428 from Edmonton,AB to Toronto,ON (Canada) with 96 people on board, was enroute at FL390 about 90nm eastsoutheast of Thunder Bay,ON (Canada) when the crew decided to turn around and divert to Thunder Bay due to a burning smell and smoke from the aft lavatory. On approach the crew advised the smoke appeared to be coming from a light in the aft lavatory and did not get any worse, they would be able to taxi in. The aircraft landed safely in Thunder Bay about 23 minutes later, attending emergency services did not need to intervene, the passengers disembarked normally.

The Canadian TSB reported maintenance identified the source of the smoke behind the aft lavatory mirror where a spare plastics soap contained had been placed but had fallen over leaking soap onto the electrical connectors of the lavatory lights. The TSB said: "The operator actioned a fleet wide campaign by disallowing cleaning services to locate the spare soap bottles behind the mirror shelf until a solution could be developed to prevent this type of event."