787 fire investigation looks at pinched battery wiring | Business & Technology | The Seattle Times
787 fire investigation looks at pinched battery wiring
Investigators believe the July 12 fire on a 787 Dreamliner at Heathrow was likely caused by incorrect installation of a battery that pinched some wires and caused a short circuit.
Boeing and government investigators now believe the July 12 fire on a 787 Dreamliner at Heathrow Airport in London was likely caused by the incorrect installation of a small lithium ion battery inside an electronic device.
If that’s confirmed, the fire was due to human error, not a Boeing design flaw.
U.K. investigators who examined the device, called an Emergency Locator Transmitter (ELT) and made by Honeywell, found that the internal wires connecting the battery to the ELT had been trapped and pinched when the cover was reattached as the batteries were inserted, according to two sources with knowledge of the matter, one inside Boeing and one outside.
In photos of what was left of the device, “You can clearly see the two wires crossed over each other. It’s quite evident the wires show evidence of being smashed,” one source said.
Installing the battery package entails unscrewing the cover of the relatively small device, dropping the battery pack of five cells into a slot and connecting the two wires that protrude from the battery pack to a receptacle in the ELT.
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The two sources suggested that Honeywell might have replaced the batteries at some stage before delivery of the jet because the devices sat on the shelf during the years-long 787 program delays.
If this were correct, it could explain why the accident happened to the 787 in particular.
Investigators are also looking at whether overheating of the batteries as they sat parked in the sun during the four-month grounding of the 787 fleet earlier this year could have led to internal damage that contributed to the failure.
There’s no evidence of moisture damaging the batteries, which had been another theory put forward in the press.