(REUTERS) A lithium-ion battery that caught fire aboard a parked Boeing 787 in 2013 in Boston had design flaws and it should not have been certified by the U.S. Federal Aviation Administration, U.S. accident investigators said on Monday.

The National Transportation Safety Board said the battery, manufactured by GS Yuasa Corp <6674.T>, experienced an internal short circuit that led to thermal runaway of the cell. This condition caused flammable materials to be ejected outside the battery’s case and resulted in a small fire, the NTSB said in its report on the incident.

The agency said its investigators found a number of design and manufacturing concerns that could have led to the short circuiting, including the presence of foreign debris and an inspection process that could not reliably detect defects.

No one was hurt in the January 2013 incident aboard a Japan Airlines <9201.T> plane. The fire broke out while the 787 Dreamliner was parked at Boston’s Logan Airport after passengers and crew had departed.

Another battery overheated on an All Nippon Airways <9202.T> plane later the same month, prompting regulators to ground the global fleet until April that year.

Boeing redesigned the battery and charger and designed a steel box to contain fires and vent hot gasses outside the plane.

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