The Boeing 787 was held at Tokyo's Narita International Airport on Tuesday after white smoke or gas was seen outside the plane. The Japan Airlines Dreamliner was empty at the time, its scheduled passengers flew to Bangkok aboard a different 787.

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."

The incident came almost exactly one year after the decision by global regulators to ground the entire fleet of 787s on January 16, 2013. This move had followed a small fire on the tarmac at Boston's Logan International Airport and another battery fault on board an All Nippon Airways 787 that forced pilots into an emergency landing. The fleet remained grounded for three months as Boeing redesigned the battery, charger and containment system - investigators never established the cause of the problems.

Safety measures 'worked'

"The issue occurred during scheduled maintenance activities with no passengers on board," Boeing said of Tuesday's incident in Tokyo. "The improvements made to the 787 battery system last year appear to have worked as designed."

Speaking to the Reuters news agency, former FAA adviser Hans Weber, now president of an aerospace technology consulting firm, said Japan Airlines' initial account of the incident appeared to support Boeing's stance. Weber said the preliminary evidence suggested Boeing's new measures to contain any battery leaks were working.

"It limited the problem to one faulty cell. It contained the problem and vented the fumes outside the airplane, as designed," Weber said.

Boeing's state-of-the-art passenger flagship, seating around 250, has had a troubled early life. It entered service more than three years behind schedule, before being pulled from the skies last year. In July, after the 787s were airborne again, an Ethiopian Airlines Dreamliner caught fire at London's Heathrow Airport, scorching the fuselage at the rear. Investigators never ascertained the cause of this case, but suspected faulty wiring of a lithium battery in an emergency beacon near the tail of the plane.

msh/slk (AP, Reuters)