Boeing to probe fresh Dreamliner fault Boeing is to investigate a wiring defect on its Dreamliner aircraft that affected a fire extinguisher system for the engines on the US manufacturer's newest and most sophisticated passenger jet. All Nippon Airways on Wednesday delayed a Dreamliner flight from Japan's Haneda airport to Frankfurt after discovering the wiring fault on the jet, but the problem was fixed and the aircraft took off. It is the latest glitch to affect the Dreamliner, which was grounded temporarily by regulators in January after lithium-ion batteries overheated on two 787s. Last month, a Dreamliner caught fire at London's Heathrow airport, and although the cause of the blaze has not been identified, investigators are focused on possible faults with equipment used to locate the aircraft if it gets into difficulties. ANA said that after finding the wiring defect on the fire extinguisher system for the engines on one 787, it inspected its other 19 Dreamliners, and discovered similar faults on a further two aircraft. Two of the three 787s with the problems have had the issues resolved, with the other one awaiting new parts. Boeing said: "We are aware of the issue and working with our customer. The safety of those flying on Boeing aeroplanes is our top priority. We will thoroughly examine this issue and take the appropriate steps. Japan Airlines said that one of its Dreamliners on Wednesday turned back part way through a flight from Narita to Helsinki after learning of the wiring problem on the ANA 787 from the airline and the Japanese transport ministry. Japan Airlines inspected all of its 10 Dreamliners, but did not discover a similar wiring defect. ANA is the largest operator of the Dreamliner. Between them, ANA and Japan Airlines operate 30 of the 73 Dreamliners in service.