Because the incident happened in Japan and involved a Japanese airline, Japanese authorities would take the lead in any investigation. If the Japan Transport Safety Board opens an investigation, the U.S. National Transportation Safety Board "would certainly participate," NTSB spokesman Peter Knudson said. The NTSB said the incident was reported to it as a "smoke event."
The NTSB expects to finish its investigation of the 787 fire in Boston by the end of March, and present findings at a public meeting this fall.
"Anything we can learn about the (latest) battery failure would be helpful" to the ongoing investigation, Knudson said.
The Federal Aviation Administration said it is working with Boeing and with the Civil Aviation Bureau of Japan to investigate the latest malfunction.
United Airlines is the only U.S. 787 operator. "Our 787s are operating normally, and we haven't experienced any issues with the batteries," spokeswoman Christen David said.
She declined to say whether United 787s were getting extra inspections, beyond the routine maintenance checks the airline gives all of its planes.
Boeing shares fell 69 cents, or a half-percent, to close at $140.01 on Tuesday.
AP transportation reporter Joan Lowy in Washington and AP writer Mari Yamaguchi in Tokyo contributed to this report.