787 Dreamliner investigation probes battery-charging electronics


787 Dreamliner investigation probes battery-charging electronics

Brian Fuller  1/22/2013 3:05 PM EST

FLAGSTAFF, Ariz.–Investigators from the U.S. National Transportation Safety Board (NTSB) arrived in Tucson, Ariz., Tuesday (Jan. 22) as the focus of electronics problems that have grounded Boeing’s 787 Dreamliner shifted to battery-charging electronics.

The NTSB team is visiting Securaplane Technologies, an avionics unit of U.K.-based Meggitt, to test the company’s battery-charging devices as well as wire bundles and battery-management circuit boards. Japanese and U.S. airlines grounded their 787s on Jan. 16 while investigators in both nations looked into battery and other problems that have plagued the airliner in recent weeks.

The Dreamliner, a huge business and technology bet for Boeing, leverages advanced electronics, millions of lines of software code and lithium ion battery technology to claim 20 percent better fuel efficiency than the Boeing 767 it’s intended to replace.

The initial Dreamliner probe focused on the LiOn battery, which powered the plane’s auxiliary power unit (APU), after one (pictured nearby) caught fire Jan. 7 in an empty plane in Boston.

The incident has similarities to an incident involving the Chevrolet Volt–a Volt LiOn battery in a crash-test vehicle caught fire in a parking lot weeks after its test.

Investigators said they examined the 32V battery using X-ray and CT scans,  disassembled the APU battery into its eight cells for detailed examination and documentation.

Three of the cells were selected for more detailed radiographic examination to view the interior of the cells prior to their disassembly, the NTSB said in a statement.

The agency added that an examination of the flight recorder data from the JAL B-787 airplane indicate that the APU battery did not exceed its designed voltage of 32 volts.

Securaplane, acquired by Meggitt in 2011, has been in business since 1986 and offers a variety of avionics including aircraft security systems, LiOn batteries and chargers and inverters–the last leveraging Vienna rectifiers, power MOSFETs/IGBTs, planar transformers, ultracapacitors, and advanced pulse width modulation techniques, according to the company’s web site.

The charger in question, the Boeing 787 BCU (schematic pictured above), uses advanced DC to DC conversion technology, patented charging algorithms, comprehensive diagnostics and fault isolation to charge the APU battery, according to company literature.

Measuring 14.7 x 5.0 x 7.7 inches and weighing 11 pounds, the rack-mounted system features 23VDC minimum and 80 Amps maximum input power and 1500W max output power.

Related stories:

Boeing delivers first 787 Dreamliner – now the real work begins
Boeing Dreamliner’s travails yields lessons for most engineers
Aircraft designers turning to simulation to avert delamination issues
The Volt and the battery-fires furor




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