This article is from the source 'nytimes' and was first published or seen on . It last changed over 40 days ago and won't be checked again for changes.

You can find the current article at its original source at http://www.nytimes.com/2013/01/21/business/global/ntsb-rules-out-a-cause-for-battery-fire-on-787-dreamliner.html

The article has changed 6 times. There is an RSS feed of changes available.

Version 1 Version 2
Safety Board Rules Out a Cause for 787 Battery Fire Safety Board Rules Out a Cause for 787 Battery Fire
(35 minutes later)
TOKYO — The National Transportation Safety Board has ruled out excess voltage as the cause of a battery fire on the Boeing 787 Dreamliner jet operated by Japan Airlines at Boston’s Logan Airport this month, the agency said on Sunday. Federal investigations said Sunday that they had ruled out excessive voltage as the cause of a battery fire on a Boeing 787 in Boston earlier this month, widening the mystery into what led to the world’s most technologically advanced jet to be grounded after a second battery-related incident last week.
Last week, governments across the world grounded the Dreamliner jet after a problem with a lithium-ion battery on a second 787 plane flown by All Nippon Airways forced the jet to make an emergency landing in western Japan. With investigators focused on the plane’s lithium-ion batteries, the National Transportation Safety Board said an examination of the data from the plane’s flight recorder indicated that the battery “did not exceed the designed voltage of 32 volts.” The fire aboard a Japan Airlines plane on Jan. 7 at Logan International Airport in Boston occurred after the passengers had gotten off.
The agency said in a statement forwarded by a Boeing Japan representative that examination of the flight recorder data from the JAL B-787 airplane indicated that the battery in the auxiliary power unit “did not exceed its designed voltage of 32 volts.” Last week, a battery problem on another 787 forced an All Nippon Airways jetliner to make an emergency landing in Japan. That incident prompted aviation authorities around the world to ground the plane, also known as the Dreamliner. The Federal Aviation Administration said last week that it would not lift the ban until Boeing could show that the batteries were safe.
On Friday, a Japanese safety official told reporters that excessive electricity may have overheated the battery in the ANA-owned Dreamliner, which was forced to make an emergency landing at Japan’s Takamatsu airport last week. But with investigators on a global quest to find out what went wrong, the safety board’s statement suggested that there might not be a rapid resumption of 787 flights. The 787 first entered service in November 2011 after more than three and a half years of production delays. Eight airlines currently own 50 787s, including United Airlines.
American investigators have examined the lithium-ion battery that powered the auxiliary unit, where the battery fire started in the JAL plane, as well as several other components removed from the airplane, including wire bundles and battery management circuit boards, the safety agency statement said. On Friday, Japanese safety officials, who are in charge of investigating the second battery incident, suggested that an overcharged battery might have caused it to overheat. Pilots decided to make an emergency landing 20 minutes after takeoff after receiving several alarms about the battery and smelled smoke in the cockpit.
On Tuesday, the investigating group will convene in Arizona to test and examine the battery charger and download nonvolatile memory from the controller of the auxiliary power unit, it added. That investigation is conducted by Japan’s transportation safety board. American investigators are assisting in the inquiry.
The GS Yuasa Corporation of Japan makes the batteries for the Dreamliner, while Thales of France makes the control systems for the battery. The GS Yuasa Corporation of Japan, one of the world’s leading lithium ion manufacturers, makes the batteries for the 787, and Thales, of France, makes the control systems for the battery. The battery is part of a complex electrical system that powers the 787. Like many other components and structures, Boeing outsourced much of the manufacturing to partners around the world.
The safety board typically conducts investigations through a process of elimination, and rules out possible causes along the way.
It said that the lithium-ion battery that powered the auxiliary power unit, a small jet engine that is used on the ground, had been examined in the safety board’s Materials Laboratory in Washington.
The battery was first X-rayed and put through a CT-scan. Investigators then disassembled it into its eight individual cells for detailed examination and documentation. Three of the cells were selected for more detailed radiographic examination to view the interior of the cells.
Investigators have also examined several other components that they removed from the airplane, including wire bundles and battery management circuit boards as well as the battery management unit, the controller for the auxiliary power unit, the battery charger and the power start unit.
On Tuesday, investigators will convene in Arizona to test and examine the battery charger and download nonvolatile memory from the auxiliary power unit controller. Several other components have been sent for download or examination to Boeing’s facility in Seattle and manufacturer’s facilities in Japan.