The head of the National Transportation Safety Board says the investigation into what went wrong with two batteries on Boeing 787s will still take a while to finish.
The NTSB is the federal agency in charge of investigating transportation accidents. Its chair, Deborah Hersman, says teams are working around the clock to figure out why one of the batteries caught fire and another created smoke.
She says her investigators discovered short circuits in the battery that ignited at Logan airport in Boston but don’t yet know the cause. She says Japanese investigators are hard at work trying to figure out why another 787 battery created smoke, triggering an emergency landing and prompting the grounding of the 787 fleet.
Hersman says the Federal Aviation Administration took the right step in grounding the planes.
"These events should not happen as far as design of the aircraft there are multiple systems to protect against a battery event like this," Hersman said. "Those systems did not work as intended. We need to understand why."
Hersman says they’re using a scanning electron microscope to analyze the battery that caught fire – looking for contaminants or defects. She says her investigators will also examine and test intact batteries.
She says a drawdown test of a battery like this takes a week and that the investigation will not be completed overnight. Hersman says they won’t be rushed because this is “a very serious air safety concern.”
