Boeing 787 Dreamliner, operated by Japanese Airlines (JAL), has suffered a yet unidentified battery problem with white smoke spotted leaking from the battery cell.
Maintenance engineers noticed the smoke outside the aircraft during regular pre-flight check-ups at Tokyo's Narita airport. Warning lights in the cockpit helped them determine the plane’s battery cells to be the source of the problem. Further examination revealed one of the plane’s eight battery cells, located in a steel box, was leaking a liquid through a relief valve designed to open when pressure inside the cell rises.
According to available information, the leaking liquid stayed contained within the steel-box. However, fumes had already leaked out.
"The incident only happened yesterday, so it's difficult to say when checks or any repairs would be complete," an official from the Japan Civil Aviation Bureau overseeing the inspections told Reuters.
The issue raises fresh concerns about the safety and reliability of the state-of-the-art carbon fibre plane, which was grounded for three months last year after problems with batteries overheating during flight were reported.
Boeing said it was "aware of the 787 issue that occurred at Narita, which appears to have involved the venting of a single battery cell".
"Venting is the process of fumes and heat being channelled outside the battery casing and the aircraft when the battery overheats," Boeing said in a statement, pointing to the fact the incident took place during regular maintenance with no passengers aboard.
"The improvements made to the 787 battery system last year appear to have worked as designed," the statement added.
However, some aerospace experts believe the incident could undermine trust in Boeing’s flagship aircraft, designed to offer better performance and efficiency than previous generations.
"The real issue with containing the problem, rather than getting to the root cause of the problem, concerns economics," said Richard Aboulafia, an aerospace analyst at Teal Group in Fairfax. "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 other related problems, 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.
The £130m Dreamliner has been caught in a string of image-damaging incidents since the design and manufacturing stages. Apart from the whole project being delayed for about three years, the plane also suffered several incidents soon after entering service involving brakes, fuel lines, electrical panels, hydraulics and other systems.
In January last year, all 50 Dreamliners operated by airlines around the world at the time were ordered to stay on the ground until Boeing redesigns the battery, charger and containment system to prevent further fire accidents. However, the exact cause of the battery fire of a JAL-operated aircraft in Boston and an All Nippon Airways plane in January last year, has not been determined.
The first incident is still being investigated by the US National Transportation Safety Board.
The US Federal Aviation Administration certified Boeing's revamped 787 battery system as safe last year and said it was working with the aircraft maker and regulators in Japan to investigate the battery malfunction. The agency has not yet released findings of a review of Boeing's design, manufacture and assembly of the 787.
After returning to service in the spring of 2013, another Dreamliner, this time operated by Ethiopian Airlines, caught fire while parked at London’s Heathrow Airport. The cause of the fire, which scorched the fuselage, has not been established. However, faulty wiring of a lithium battery in an emergency beacon was named to be the most likely culprit.