U.S. safety officials and Boeing inspectors joined a Japanese investigation Friday into the 787 jet at the centre of a worldwide grounding of the technologically advanced aircraft.
Japanese TV footage showed the American investigators, one each from the Federal Aviation Administration and the National Transportation Safety Board and two from Boeing Co., inspecting the All Nippon Airways jet on the tarmac at Takamatsu airport in western Japan.
The investigation is being led by the Japan Transport Safety Board.
The pilot of the ANA plane made an emergency landing Wednesday morning after he smelled something burning and received a cockpit warning of battery problems. All passengers evacuated the plane on emergency slides.
The American inspectors were expected to examine the battery later Friday, said Mamoru Takahashi, a JTSB official.
In the wake of the incident, nearly all 50 of the 787s in use around the world have been grounded. Aviation authorities in Japan have directed ANA, which owns 17 of the planes, and Japan Airlines, with seven, not to fly the jets until questions over their safety have been resolved.
The 787, known as the Dreamliner, is Boeing's newest jet, and the company is counting heavily on its success. Since its launch after delays of more than three years, the plane has been plagued by a series of problems including a battery fire and fuel leaks.