The US National Transportation Safety Board (NTSB) has confirmed the source of the fire in a final report on the incident relating to a Japan Airlines 787 that was parked at an arrivals gate at Boston Logan International Airport after the aircraft had completed an intercontinental flight to Boston.
On January 7, 2013, ground workers discovered smoke and flames coming from an auxiliary power unit lithium-ion battery of the aircraft. There were no injuries to any of the 183 passengers or 11 crewmembers that had already left the plane after flying from Tokyo’s Narita Airport. The battery was manufactured by GS Yuasa Corporation.
"The investigation identified deficiencies in the design and certification processes that should have prevented an outcome like this," said NTSB Acting Chairman Christopher A. Hart. "Fortunately, this incident occurred while the airplane was on the ground and with firefighters immediately available."
Because the APU and main lithium-ion batteries installed on the 787 represented new technology not adequately addressed by existing regulations, the USA’s Federal Aviation Administration required that Boeing demonstrate compliance with special conditions to ensure that the battery was safe for use on a transport category aircraft.
Investigators said that Boeing’s safety assessment of the battery, which was part of the data used to demonstrate compliance with these special conditions, was insufficient because Boeing had considered, but ruled out, cell-to-cell propagation of thermal runaway (which occurred in this incident) but did not provide the corresponding analysis and justification in the safety assessment. As a result, the potential for cell-to-cell propagation of thermal runaway was not thoroughly scrutinized by Boeing and FAA engineers, ultimately allowing this safety hazard to go undetected by the certification process.
As a result of its findings, the NTSB is recommending that the FAA improve the guidance and training provided to industry and FAA certification engineers on safety assessments and methods of compliance for designs involving new technology.
NTSB investigators also identified a number of design and manufacturing concerns that could have led to internal short circuiting within a cell.
As a result of the investigation, the NTSB made 15 safety recommendations to the FAA, two to Boeing, and one to GS Yuasa.
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