Design flaws in the 787’s lithium-ion APU battery which caused the fire that grounded the global fleet should have been picked up during the design and certification process, according to the US National Transportation Safety Board (NTSB).
Following an investigation, the NTSB concludes the 2003 fire was caused by an internal short circuit in one of the battery cells, which caused a problem that spread to the other cells.
Boeing’s safety assessment of the battery ruled out the possibility of such an event occurring, but “did not provide the corresponding analysis and justification". As a result, the issue “was not thoroughly scrutinised by Boeing and FAA engineers, ultimately allowing the safety hazard to go undetected by the certification process”, states the NTSB.
The body has made 15 recommendations to the FAA, including that the methods of compliance for designs involving new technology are improved. The NTSB’s full report is available for download from www.ntsb.gov.