Boeing 787 DreamlinerEnlarge Photo
People take air safety pretty seriously, so when smoke filled the cabin of a new Boeing 787 Dreamliner aircraft a few months back, the entire fleet was quickly grounded.
It turned out to be an issue with the aircraft's lithium-ion batteries, used to power some secondary functions reducing load on the engines, and therefore fuel.
Boeing has now announced the improvements it's making to the 787's batteries--which aren't the same as those used in electric vehicles--currently undergoing strict certification testing.
According to Electric Vehicles Research, the new batteries will feature several layers of additional safety features to prevent the previous issues arising.
Each problem solved
The first layer of improvements starts right from the GS Yuasa battery factory in Japan, where new production methods and tests are in place to make sure there's as little variation as possible between individual cells in the batteries, and between the batteries themselves. Each cell will undergo ten distinct tests, including 14 days of monitored discharge cycles.
The battery's state of charge has been addressed too, allowing a lower maximum charge and higher minimum, reducing stress on the battery during charge and discharge cycles.
Batteries should now be better protected against problems with individual cells too, with an electrical insulator between cells to prevent problems spreading, and thermal insulation helps prevent the heat of cells affecting the performance of cells around it.
New wire sleeving is more chafe and heat-resistant, and new locking fasteners hold the battery's cells together. Battery casing now also features holes, letting moisture drain out the bottom, and helping a battery vent away from other units should failure occur. The stainless steel casing itself isolates the batteries from other equipment, and the battery enclosure features a vent to carry battery vapors outside the aircraft.
The improved batteries are now undergoing engineering testing to demonstrate the effectiveness of the changes--stressing the batteries to far greater limits than they'd experience during failure.
Testing has shown that fire can no longer occur in the battery enclosure--thanks to seals that prevent oxygen entering the enclosure--and that failures in individual cells cannot affect others--all demonstrated to gain FAA approval.
Once these tests are complete and the aircraft has gained approval, operators will finally be able to resume commercial flights.
"As soon as our testing is complete and we obtain regulatory approvals, we will be positioned to help our customers implement these changes and begin the process of getting their 787s back in the air," said Boeing Commercial Airplanes President and CEO Ray Conner.
"Passengers can be assured that we have completed a thorough review of the battery system and made numerous improvements that we believe will make it a safer, more reliable battery system."
[Hat tip: Brian Henderson]