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New safety upgrades could make this possible

Boeing could have its 787 Dreamliner jets back in the sky in "weeks" instead of months thanks to a few new safety upgrades.

According to Boeing, the safety upgrades include improved production/operating processes, adjustments to the battery itself and a new enclosure for the battery.

"Our first lines of improvements, the manufacturing tests and operations improvements, significantly reduce the likelihood of a battery failure," said Mike Sinnett vice president and chief project engineer of the 787 program. "The second line of improvements, changes to the battery, helps stop an event and minimize the effect of a failure within the battery if it does occur. And the third line of improvements, the addition of the new enclosure, isolates the battery so that even if all the cells vent, there is no fire in the enclosure and there is no significant impact to the airplane."

Improved production/operating processes entails more rigorous testing. Boeing partnered with battery maker GS Yuasa and integrated power conversion system provider Thales to come up with new testing methods. Now, there are 10 different tests that battery cells must undergo over a 14-day screening period.

They've also adjusted the acceptable level of charge for the battery by lowering the highest charge allowed and raising the lowest level allowed.


As for the battery itself, two kinds of insulation were added: an electrical insulator and a thermal insulator, which will wrap around/below each battery cell to keep them away from each other and the battery case.

The wire sleeving and wiring within the battery were also upgraded to be resistant to heat and chafing. In addition, small holes were added to the bottom of the battery case to allow moisture to drain, and larger holes will allow the battery to vent if it fails.

As far as the new enclosure goes, it is made of stainless steel and will make sure no wire can ignite inside. It has a direct vent to carry battery vapors outside of the plane and isolates the battery from the rest of the equipment.

“It is reasonable to expect that we could be back up and going in weeks, not in months,” said Sinnett. “We understand the work to be done and we’ve got a fairly good notion of how long it will take, and if we miss, it will be by a little, not by a lot.”

Boeing's 787 Dreamliner suffered many issues back in Janury of this year. It started with a 787 operated by Japan Airlines, which had experienced an electrical fire at Boston's Logan International Airport after coming in from Tokyo. According to the National Transportation Safety Board, a battery in the auxiliary power unit suffered severe fire damage.

One day later, a Boeing 787 operated by the same airline at the same airport suffered a fuel leak.

Later,
a 787 Dreamliner with All Nippon Airways (ANA), which had arrived at the Matsuyama airport in western Japan from Tokyo on Friday, developed a web-like crack in the cockpit window. That same day, another 787 Dreamliner with ANA had an oil leak after traveling to the Miyazaki airport in southern Japan.

Finally, an ANA 787 flight to Tokyo had an issue with its main battery only 15 minutes into a 90-minute flight. After 40 minutes, a burning smell made its way into the cabin and cockpit, and the plane made an emergency landing at Takamatsu Airport on the southern island of Shikoku. This issue caused all 787s to be grounded in Japan, the U.S. and India until a safety investigation was conducted and the problems were corrected.

Source: Boeing



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RE: stating the obvious
By Fireshade on 3/19/2013 7:09:57 AM , Rating: 2
quote:
The problem was the batteries weren't supposed to catch fire in the first place, but they had two incidents within the first few months of service. Which led to a reassessment of the fire risk, forcing a redesign which assumed a higher frequency of fire. So now they're adding things like isolating different cells from each other so a fire doesn't spread as easily between cells.

Rightly put.
From other technological articles on the Dreamliner solution, you can tell that Boeing's fix only addresses the symptoms. They have not yet found and solved the problem itself, i.e. they still don't know why the batteries can become instable/overheated.

Apparently Boeing and its partners are comfortable with these kind of fixes, when money is at stake. Which is really bad, because it means that money is more important than intrinsically safe design.


"So, I think the same thing of the music industry. They can't say that they're losing money, you know what I'm saying. They just probably don't have the same surplus that they had." -- Wu-Tang Clan founder RZA














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