Story highlights Japan Airlines hands over 787 battery unit to Boeing for investigation

The NTSB says it's ready to assist Japanese officials in the probe

A smoking battery was reported aboard a Japan Airlines 787 Dreamliner Tuesday

Fears of overheating batteries prompted 787s to be grounded worldwide a year ago

Nearly nine months after it returned to the sky and its battery system was declared safe, new reports surfaced Tuesday of smoke aboard a Boeing 787 Dreamliner at Tokyo's Narita International Airport.

The incident "appears to have involved the venting of a single battery cell," aboard a Japan Airlines 787, Boeing told CNN in a statement. A year ago, overheated batteries aboard two Dreamliners prompted aviation officials to ground all 50 of the planes worldwide.

Tuesday's incident "occurred during scheduled maintenance activities with no passengers on board," the Boeing statement said. "The improvements made to the 787 battery system last year appear to have worked as designed." Boeing said it was working with Japan Airlines to return the plane to service.

Japan Airlines and the government's Japanese Aviation Bureau told CNN Tuesday night that the battery unit was removed from the aircraft to be handed over to manufacturers Boeing/Yuasa for further investigation. The airline told Flightglobal that the plane sustained no damage. JAL is monitoring their other 787s as a precautionary measure, Flightglobal reported.

Boeing's stake in the Dreamliner is huge. Hundreds of millions of dollars are riding on the success of the 787, which represents a new generation of lighter, more efficient money making planes.

When it began service in 2011, the Dreamliner boasted a new battery system that used new, lighter lithium-ion batteries. After the planes were grounded, Boeing and the Federal Aviation Administration collaborated on a new battery compartment . The compartment was designed to insulate the batteries in a ventilated armor-plated box to protect the rest of the plane in case of a fire caused by overheating batteries. The NTSB announced this month it plans to issue a final investigation report later this fall.

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The National Transportation Safety Board said it was aware of Tuesday's battery incident in Japan.

"By international treaty, aviation accidents and incidents are investigated by the investigative authority in the country in which the accident or incident occurred.

"If the Japan Transport Safety Board opens an investigation into the battery smoke event, the NTSB stands ready to assist," the U.S. agency said in a statement.

Tuesday's incident comes nearly two months after Boeing warned airlines about another 787 concern: possible icing problems in its GE engines.

The aircraft manufacturer alerted 787 operators after instances of "ice crystal icing that resulted in temporary diminished engine performance," Boeing said in a statement.

Although it said only a small number of the engines have experienced the ice problems, Boeing advised pilots to keep planes at least 50 nautical miles from storms that may contain ice crystals until General Electric can make improvements to the "GEnx" engines.

The Dreamliner's development was marked by production delays and other problems. Then, a year ago this month, batteries were blamed for two overheating instances on a Japan Airlines 787 in Boston and on an All Nippon Airways 787 in Japan. No one was hurt in either case, but concerns about the incidents spurred the FAA to ground all U.S. Dreamliners. Officials around the world followed suit.

Experts say every airliner experiences "teething pains" during its first few years of service, as minor problems are shaken out. But the FAA's decision to ground the Dreamliner put it under intense scrutiny.

United Airlines is the lone U.S. operator of Boeing 787s.

In an apparent show of confidence in July, United announced it was ordering 20 new 787-10 models, which are a longer version of the plane.