At a press conference in Tokyo on Friday to present changes to the Dreamliner jet's battery system, Boeing executives said the root cause of two battery failures onboard 787s is still unknown — and will likely remain that way.
Figuring out exactly why one of eight cells in the lithium ion battery of a Dreamliner in Boston short circuited could take years, said Vice President and Chief Project Engineer Mike Sinnett.
So, President and CEO of Boeing Commercial Planes Ray Conner explained, the team came up with a "comprehensive and robust set of solutions" that should prevent future failures, and contain the damage if they do occur — whatever the cause.
In short, Boeing does not know what went wrong, so it added a bunch of measures to cover a variety of potential problems.
Those changes come in three layers: stopping battery cells from "venting" in the first place, preventing possible venting from propagating throughout the battery, and making sure the plane is not damaged if all that happens anyway.
When a reporter questioned the choice to abandon the search for the root cause, Sinnett said the approach is not unusual for issues in aviation, and that there are "many cases" where the "comprehensive" approach has sufficed.
Later in the press conference, Sinnett came back to the question:
We could spend the next two years trying to figure out what the one specific root cause was, or we could design to make sure that we've covered everything. And so that's what we've done here.
It's "the same type of approach we've used forever," he added.
The FAA approved the planemaker's certification plan for changes to the 787's battery system on Tuesday. The testing process is now about one third complete and should be finished within a few weeks.
"I feel more confident now," Sinnett said, adding that the Dreamliner will be "absolutely" safe.
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