The National Transportation Safety Board has released its findings regarding the investigation it conducted following the events that led to the grounding of 50 long-range Boeing 787s. According to its report, a series of failures have been attributed to the Federal Aviation Administration (FAA), Boeing Co., and its supplier of lithium-ion batteries.
Back in January 2013, ground workers at Boston Logan International Airport noticed that smoke and flames were coming from an auxiliary power unit lithium-ion battery that was in a Japan Airlines 787 Dreamliner that was parked at a gate. A second incident involving the battery, manufactured by GS Yuasa Corp, occurred days later on another 787 Dreamliner that resulted in the grounding of 50 787s for over three months.
Initial investigations by the NTSB determined that the fire began after one of the eight cells in the battery experienced an internal short circuit that caused a thermal runaway in the affected cell and then spread to the remaining cells. Thermal runaway is the result of an increase in temperature that then changes conditions, which causes an additional increase in temperature, which can lead to a destructive result.
"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."
Due to the fact that the APU and main lithium-ion batteries were new technology that had been installed on the 787, they were not adequately addressed by current FAA regulations. In addition, Boeing’s safety assessment of the device was insufficient due to the company ruling out cell-to-cell circulation of thermal runaway. The NTSB also discovered a number of design and manufacturing concerns that could have been responsible to the internal short-circuiting in the cells.
The NTSB’s investigation has resulted in 15 safety recommendations to the FAA, two to Boeing, and one to GS Yuasa.