The US National Transportation Safety Board (NTSB) in its preliminary report on the 787 Dreamliner battery fires, that they discovered signs of short circuiting and indications of thermal runaway, when extreme temperatures spark chain reactions, the Shipping Gazette informs.
"As we learn more in this investigation, we will make recommendations for improvements to prevent a recurrence," NTSB chairwoman Deborah Hersman told a press conference on the January 7 onboard batter fire in Boston.
After saying it could not comment on an on-going investigation, 787 manufacturer Boeing declared: "The company has formed teams consisting of hundreds of engineering and technical experts who are working around the clock with the sole focus of resolving the issue and returning the 787 fleet to flight status."
Said Ms Hersman: "We have not ruled anything out as a potential factor in the battery fire; there are still many questions to be answered."
Referring to the B-787 battery incident in Japan on January 16, which is being investigated by the Japan Transport Safety Board, Ms Hersman said: "One of these events alone is serious; two of them in close proximity, especially in an airplane model with only about 100,000 flight hours, underscores the importance of getting to the root cause of these incidents."
Ms Hersman also worried about the adequacy of fire prevention systems. "The investigation will include an evaluation of how battery fire could have defeated the safeguards," she said, according to Atlanta area Air Cargo World.
The batteries were manufactured by GS Yuasa for the Thales electrical installation and are unique to the Boeing 787. The same battery models are used for the main aircraft battery and for the battery to start the auxiliary power unit, which is the one that caught fire in Boston, said the report.
Radiographic examinations of the incident battery and an exemplar battery were conducted at an independent test facility. The digital radiographs, or computed tomography (CT) scans, generated from these examinations allowed NTSB investigators to document the internal condition of the battery before disassembly, said the report.
Ongoing lab work includes an examination of the battery elements with a scanning-electron microscope and energy-dispersive spectroscopy to analyse the elemental constituents of the electrodes to identify contaminants or defects, it said.
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