A United States regulator has released a detailed description of a battery fire on board a Boeing 787 Dreamliner but has not specified a cause.
The National Transportation Safety Board is investigating the incident which occurred in Boston in January.
In its interim report it says it is still looking into the probable cause of the fire, the BBC reports.
In a separate incident later in the same month, on an All Nippon Airways flight, smoke was reported coming from the Dreamliner's battery, but no flames.
The incident led to all 50 of the operational crafts being grounded and airlines that operate the Dreamliners have been forced to find alternatives for scheduled flights in their fleets.
Some have said they will seek compensation from Boeing for the losses arising from the groundings.