A fuel leak in a Japan Airlines 787 during maintenance work at Narita International Airport was due to a malfunction in the valve of a fuel pipe caused by flaws in coating, the transport ministry said Friday.
About 100 liters of jet fuel leaked from the valve as maintenance engineers were removing fuel from the Boeing plane Jan. 13, the Land, Infrastructure, Transport and Tourism Ministry said.
An indicator in the cockpit showed the valve was closed when it was in fact open.
Ministry officials asked the British maker of the valve to check the problem with a valve actuator. An investigation found that unnecessary coating was applied to it, causing the motor switch for the valve not to function properly.
The same JAL 787 had leaked fuel earlier in January at Boston’s Logan International Airport, causing its takeoff to be scrubbed. An investigation found that a different valve failed to close because a foreign substance had become stuck in the fuel tank. After that problem was fixed, the plane was flown to Narita.
Boeing 787 jets worldwide have been grounded since one of the aircraft operated by All Nippon Airways Co. made an emergency landing in January due to smoke in the cockpit. This has led to massive probes into the 787 electrical system, particularly its lithium-ion batteries.