Boeing reveals details of 787 battery changes
, March 15, 2013
Boeing today announced that a comprehensive set of improvements that will add several layers of additional safety features to the lithium-ion batteries on 787 commercial jetliners are in production and could be ready for initial installation within the next few weeks.
New enclosures for 787 batteries also are being built and will be installed in airplanes in the weeks ahead, it said.
These improvements, which continue to undergo extensive certification testing, will allow operators to resume commercial flights with their 787s as soon as testing is complete and the US Federal Aviation Administration (FAA) and other international regulators grant their final approval.
The improvements include enhanced production and operating processes, improved battery design features and a new battery enclosure, it said.
“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.”
Battery system changes include changes to the battery itself, the battery charging unit and the battery installation.
Earlier this week the FAA approved Boeing’s certification plan, which lays out the discrete testing to be done to demonstrate that the battery improvements address the conditions laid out in the Airworthiness Directive that has suspended 787 commercial operations.
Development Team Created Solution
The enhancements to the battery system address causal factors identified by the Boeing technical team as possible causes of battery failure. The technical team’s findings also were verified by an independent group of lithium-ion battery experts from a number of industries, universities and national laboratories.
“We’ve come up with a comprehensive set of solutions that result in a safer battery system,” said Mike Sinnett, vice president and chief project engineer, 787 program, Boeing Commercial Airplanes. “We have found a number of ways to improve the battery system and we don’t let safety improvements go once they are identified. We incorporate them into our processes and products.”
Enhanced Production Controls and Operating Processes
The first layer of improvements is taking place during the manufacture of the batteries in Japan. Boeing teamed with Thales, the provider of the integrated power conversion system, and battery maker GS Yuasa to develop and institute enhanced production standards and tests to further reduce any possibility for variation in the production of the individual cells as well as the overall battery.
“We’ve all developed a better understanding of the sensitivities of this technology to variations during the manufacturing process,” said Sinnett. “And we all feel the need to increase monitoring of this process on an ongoing basis.”
Four new or revised tests have been added to screen cell production, which now includes 10 distinct tests. Each cell will go through more rigorous testing in the month following its manufacture including a 14-day test during which readings of discharge rates are being taken every hour. This new procedure started in early February and the first cells through the process are already complete. There are more than a dozen production acceptance tests that must be completed for each battery.
Boeing, Thales and GS Yuasa have also decided to narrow the acceptable level of charge for the battery, both the lowering the highest charge allowed and raising the lower level allowed for discharge. Two pieces of equipment in the battery system – the battery monitoring unit and the charger are being redesigned to the narrower definition. The battery charger will also be adapted to soften the charging cycle to put less stress on the battery during charging, the statement said.
Improved Battery Design Features
Changes inside the battery will help to reduce the chances of a battery fault developing and help to further isolate any fault that does occur so that it won’t cause issues with other parts of the battery, it said.
To better insulate each of the cells in the battery from one another and from the battery box, two kinds of insulation will be added. An electrical insulator is being wrapped around each battery cell to electrically isolate cells from each other and from the battery case, even in the event of a failure. Electrical and thermal insulation installed above, below and between the cells will help keep the heat of the cells from impacting each other.
Working towards Resuming Flights
“We are following all of the necessary protocols to get our new design fully approved and properly installed so that we can help our customers start flying as soon as possible. We’re simultaneously moving out on an effort to resume deliveries but completing our certification work and getting the delivered fleet flying again is our first priority,” said Conner. “Our customers and their passengers have been incredibly patient as we have worked through this process and we thank them very sincerely for their continued support and confidence in the 787.
“The more-electric architecture of the 787 brings real value not just to the airlines but to our industry. By reducing fuel use, we are reducing our environmental footprint. This battery technology is an important part of the more-electric architecture, which is helping us to cut fuel use by more than 10 billion gallons of fuel over the life of this program.
“New technologies require extra attention and hard work, but the benefits are real,” he said- TradeArabia News Service