A battery that overheated on a Boeing 787Â flight in Japan and forced the plane to make an emergency landing wasÂ incorrectly wired, an investigation has found.
The All Nippon Airways (ANA) DreamlinerÂ touched down in Takamatsu when the lithium ion battery sparked an on-board fire,Â prompting the worldwide grounding of the Boeing 787 jets due to safetyÂ concerns.
Japan’s Transport Safety Board has said theÂ battery for the aircraft’s auxiliary power unit was improperly connected to theÂ main battery, which overheated during the flight.
The board’s report said a protective valveÂ would have prevented power from the auxiliary unit from causing damage,Â the HuffingtonÂ PostÂ said.
The fact that lights on theÂ aircraft’s tailÂ and wings were flickering after the emergency landing,Â and that the mainÂ battery was switched off, led investigators toÂ conclude there was an abnormalÂ current travelling from the auxiliaryÂ power unit.
This was down to miswiring, the reportÂ said.
The Transport Safety Board will carry outÂ further analysis to determineÂ what caused the main battery to overheat andÂ begin smoking.
The incident on January 16 came days after aÂ battery exploded on a Dreamliner parked at Boston’s Logan InternationalÂ Airport.
A mechanic conducting a routineÂ post-flightÂ inspection on the Boeing 787 jet discovered smoke in theÂ cockpit.
Passengers had disembarked the plane just 15Â minutes before the blaze broke out.
After the fault on the ANA domestic flight onÂ January 16, the Federal AviationÂ Administration and aviation authorities inÂ other countries took theÂ decision to ground 787 fleets.
The Boeing 787 is the first airliner to makeÂ extensive use of lightweight lithium ion batteries.
The batteries are quicker to charge andÂ contain more energy thanÂ conventional batteries of the same size, but are alsoÂ more susceptibleÂ to overheating.
Aircraft manufacturer Airbus has switchedÂ from lithium ion batteries to traditional nickel-cadmium batteries for its newÂ A350 passenger jet in the wake of the problems plaguing competitor Boeing’sÂ Dreamliner fleet.
It said it had taken the decision to prevent further delays in delivering its new new passenger jet amid uncertainty over whether the investigations into Boeing’s battery problems will lead to a regulation overhaul.