Japanese investigators are studying x-ray images of a lithium ion battery that overheated earlier this week aboard a Boeing 787 Dreamliner at the Narita airport in Tokyo.
The images were acquired by the battery manufacturer, Japanese firm GS Yuasa, at about the time the battery was leaving the factory. The company scans all eight-cell batteries with an x-ray-like system before they are shipped, as a part of a standard procedure. The images are checked for a list of potential problems to ensure the batteries are not flawed, said John Goglia, a former National Transportation Safety Board (NTSB) member.
The investigators will now search for signs of possible anomalies, hoping they might find answers also to earlier Dreamliner battery problems. As the battery involved in this week's accident survived in a better shape than those of the two aircraft that caught fire last year, forcing the whole fleet to be grounded, the investigators hope they might find clues they might have previously missed.
"They'll now go back and examine those (the images) to see if there's anything they missed," Goglia said.
GS Yuasa declined to comment on whether it was looking at x-rays of the battery cells.
The Japan Civil Aviation Bureau (JCAB) is investigating the accident with the help of GS Yuasa, Boeing and JAL. Investigators from the US National Transportation Security Board the Japan Transport Safety Board (JTSB), who were responsible for investigating the last year’s incidents, are also involved.
Goglia said engineers, maintenance people and Boeing employees have told him the latest battery rupture appears so far to be a single event, rather than a problem that is likely to repeat itself. He noted Boeing has not issued a service bulletin to airlines recommending action.
"If they find something in the review process that's a concern, they would issue a bulletin, but so far there's no indication of what the root cause of the failure was," he said. "If they don't know what's wrong, they don't know how to fix it."
Investigators also are likely to look for a voltage spike or other abnormality in the data that is gathered by sensors in the battery system, said Michel Merluzeau, managing partner at G2 Solutions, an aerospace and defence consulting firm in Kirkland, Washington.
He and Goglia both noted the containment system had worked as planned, by stopping the problem from affecting other cells of the battery, and not damaging the plane.
"I think it's a vindication of the fix," Merluzeau said.
The battery is used to "bring the airplane to life" by powering its systems before the plane's own gas-powered generator is started, according to Boeing.