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| Boeing 787 Dreamliner tests 'missed fire risk' | Boeing 787 Dreamliner tests 'missed fire risk' |
| (about 9 hours later) | |
| Tests on Dreamliner batteries carried out by Boeing when they were first certificated for flight missed the high risk of fire, US regulators have said. | Tests on Dreamliner batteries carried out by Boeing when they were first certificated for flight missed the high risk of fire, US regulators have said. |
| Boeing's tests underestimated the frequency of "smoke events" in the lithium ion batteries, the National Transportation Safety Board said. | Boeing's tests underestimated the frequency of "smoke events" in the lithium ion batteries, the National Transportation Safety Board said. |
| They also failed to spot that overheating in one battery cell could cascade to the others, causing a fire. | They also failed to spot that overheating in one battery cell could cascade to the others, causing a fire. |
| The regulator said it still had many more leads to investigate. | The regulator said it still had many more leads to investigate. |
| On Wednesday, the NTSB said it would take weeks for it to complete its investigations. Its head, Deborah Hersman, said the regulator hoped to produce an interim factual report - but not a final report - within 30 days. | On Wednesday, the NTSB said it would take weeks for it to complete its investigations. Its head, Deborah Hersman, said the regulator hoped to produce an interim factual report - but not a final report - within 30 days. |
| The ultimate decision to allow Boeing's 787 Dreamliners to re-enter service will be taken by the Federal Aviation Administration in the US, and by other countries' air regulators in the rest of the world. | The ultimate decision to allow Boeing's 787 Dreamliners to re-enter service will be taken by the Federal Aviation Administration in the US, and by other countries' air regulators in the rest of the world. |
| The NTSB head said that Boeing's safety checks suggested that a smoke event would occur less than once every 10 million flight hours. | |
| But the 787 planes have only clocked up 100,000 hours of flight-time since entering commercial services, and have experienced two battery fires. | But the 787 planes have only clocked up 100,000 hours of flight-time since entering commercial services, and have experienced two battery fires. |
| The 50 Dreamliners in service have been grounded since 16 January, after a battery in a Japan Airlines 787 plane caught fire in Boston, and an All Nippon Airways flight was forced to make an emergency landing because of a battery malfunction. | The 50 Dreamliners in service have been grounded since 16 January, after a battery in a Japan Airlines 787 plane caught fire in Boston, and an All Nippon Airways flight was forced to make an emergency landing because of a battery malfunction. |
| So far, the regulator has discovered that the Boston fire was caused by a short circuit within one of the cells of the plane's multi-cellular batteries, and that a fault in the battery's design allowed the resulting overheating to spread to the other cells. | So far, the regulator has discovered that the Boston fire was caused by a short circuit within one of the cells of the plane's multi-cellular batteries, and that a fault in the battery's design allowed the resulting overheating to spread to the other cells. |
| However, the NTSB has not yet found out what caused the short circuit in the first place. | However, the NTSB has not yet found out what caused the short circuit in the first place. |
| Ms Hersman said they were now following up two lines of inquiry - the actual cause of the short circuit, and why the certification process failed to pick up the defect in the battery's design. | Ms Hersman said they were now following up two lines of inquiry - the actual cause of the short circuit, and why the certification process failed to pick up the defect in the battery's design. |