Japan Airlines said that the Boeing 787 Dreamliner jet under investigation following a fuel leak at Boston airport last week, leaked fuel during tests in Japan on Sunday (January 13).
An open valve on the aircraft caused fuel to leak from a nozzle on the left wing used to remove fuel, a company spokeswoman said.
The jet was out of service after spilling about 40 gallons (roughly 150 liters) of fuel onto the airport taxiway in Boston due to a separate valve-related problem.
In Boston, a different valve on the plane opened, causing fuel to flow from the center tank to the left main tank.
The causes of both incidents are unknown, and there is no timetable for the plane to return to service, the JAL spokeswoman added.
The 787 represents the boldest bet Boeing has made on a new plane in more than a decade, and because the aircraft required billions to develop, much of the company's financial performance is riding on its success.
Boeing is trying to double production to 10 jets a month this year to cash in on nearly 800 orders.