What happened
On 24 August 2019, a Boeing 777-36, registration G-STBB, was performing a commercial passenger flight from London Heathrow Airport to JFK Airport, New York. During the early stages of the cruise phase, the commander was notified by the senior cabin crew member of a suspected fire in the aft galley. Shortly after this report, the crew confirmed that blue smoke was coming from an oven unit.
In response to the event, the cabin crew executed standard fire drill procedures, while the flight crew performed the 'smoke, fire or fumes' checklist. The crew also notified Air Traffic Control of the situation. To mitigate the issue, the flight crew electrically isolated the aft galley, which resulted in a reduction in the rate of smoke production, though smoke continued to linger in the area. The commander elected to divert the aircraft to Shannon, Ireland. The aircraft performed an overweight landing at Shannon, which was completed without incident, and all 302 passengers and 17 crew members disembarked without any injuries.
The investigation
Following the diversion, the aircraft operator's engineers conducted an examination of the oven located in the aft galley. Their inspection identified that an electrical fault within an oven fan unit was the source of the smoke. The engineers replaced the faulty fan unit, after which the aircraft was cleared to return to service. The investigation noted that the operator did not perform any further investigation into the specific failure of the oven fan unit.