TOKYO, Jan 15 (Reuters) - Japan Airlines Co Ltd said it temporarily grounded one of its Boeing 787 Dreamliners on Tuesday after white smoke was spotted outside the plane as cockpit warning lights indicated potential problems with the main battery and charger, and a battery cell appeared to be leaking.
The incident raised new concerns about the 787's safety and reliability about one year after the global 787 fleet was grounded by regulators following the overheating of two batteries.
Boeing Co said it was "aware of the 787 issue that occurred Tuesday afternoon at Narita, which appears to have involved the venting of a single battery cell." It referred to the process of fumes and heat being channeled outside the aircraft.
Boeing shares fell 0.6 percent to $139.87 on the New York Stock Exchange.
The incident, which was disclosed by Japan Airlines early on Wednesday, came nearly a year to the day after Japan Airlines and All Nippon Airways grounded their 787 fleets after two 787 batteries overheated on two different planes in less than two weeks.
Global regulators grounded the worldwide fleet on Jan. 16, 2013. The 787s remained grounded for more than three months while Boeing redesigned the battery, charger and containment system to ensure battery fires would not put the airplane at risk. The cause of the battery problems has not been determined.
United Airlines spokesperson Christen David said the company was looking into the matter. United is the only U.S. carrier that uses the 787.
Japan Airlines said maintenance engineers who were in the cockpit saw white smoke outside the plane. When they went outside the aircraft the smoke had dispersed.
On returning to the cockpit, the engineers found warning lights indicating possible faults with the main battery and charger. When they checked the battery they found one of eight cells was leaking a liquid.
The plane, due to depart from Tokyo Narita airport for Bangkok, was taken out of service, and the 158 passengers due to board the plane were put on a separate 787, JAL said.
Aerospace experts said the incident was troubling, but were cautious about drawing broader conclusions. Richard Aboulafia, an aerospace analyst at Teal Group in Fairfax, Virginia, said the incident raised two questions: whether the new system that contains the problem had worked, and whether the root cause of the battery problems will ultimately be discovered.
"The real issue with containing the problem, rather than getting to the root cause of the problem, concerns economics," Aboulafia said. "Incidents can be successfully contained, but if you continue to see incidents like these, you've got a mounting bill from taking jets offline, and repairing their battery systems. You've got an image problem, too."
Hans Weber, a former FAA adviser and president of TECOP International, an aerospace technology consulting firm, said the incident might provide more clues about the cause of the problem, such as overcharging.
He said it appeared the containment system worked. "It limited the problem to one faulty cell. It contained the problem and vented the fumes outside the airplane, as designed," he said, basing his comments on JAL's initial statements about the incident.