Final Report


On 17 April 2016, a Boeing 787-9, registered N36962, operated by United Airlines as flight UAL870, departed Sydney New South Wales (NW) for San Francisco, United States.

During the departure, cabin crew switched on the aft galley ovens in preparation for meal services. As soon as the ovens were switched on, there was a short burst of smoke, which set off a fire alarm in a nearby toilet for about one minute. One of the ovens displayed a FAILURE message. Several cabin crew detected a strong chemical odour and an electrical smell as well as a blue haze. The oven interactive screen displayed a “Critical Error-Broken Fuse” message.

The cabin crew switched off all electrical sources to the aft galley. The captain was advised. After consultation with the ground-based technical operations maintenance controller, flight crew and cabin crew, a decision was made to return the aircraft to Sydney.

The crew advised ATC via a PAN call (uncertainty phase) and the aircraft landed without incident in Sydney with emergency services in attendance.

The airline had a similar incident with another Boeing 787-9 on 2 June 2016.

After extensive testing by the oven manufacturer and Boeing, it was found that the ovens had not been updated with the latest version of software, which addressed a known problem. The oven manufacturer is now updating the software in all relevant aircraft in United Airlines fleet.

This incident highlights the correct management of an abnormal situation with effective crew coordination. Each crew member responded effectively and the situation was professionally managed by the captain.


Aviation Short Investigations Bulletin - Issue 50

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