US regulator grounds all Dreamliners The safety crisis surrounding Boeing's ultra-modern 787 Dreamliner deepened on Wednesday when the US's aviation regulator ordered all US-registered operators of the aircraft to ground them until they could prove their batteries were safe. The Federal Aviation Administration's action followed a second apparent fire in a battery on one of the airliners, which came into service in September 2011. In the latest incident, an All Nippon Airlines 787 had to make an emergency landing early on Wednesday at Takamatsu in western Japan after the pilot received an emergency indication about the battery and noticed a strange smell. That incident follows a fire in a battery on a Japan Airlines 787 on January 7 at Boston Airport. The FAA made it clear that, despite confusion about the second incident's exact circumstances, it regarded the incident as having involved the risk of a serious fire. The FAA's move is likely to prompt other aviation regulators worldwide to take similar action, grounding all the 787s still in operation. Both ANA and JAL had already announced they were grounding their fleets - which make up for around half the 50 aircraft already operating. "The battery failures resulted in release of flammable electrolytes, heat damage, and smoke on two Model 787 aeroplanes," the FAA said. The root cause of these failures is currently under investigation. These conditions, if not corrected, could result in damage to critical systems and structures, and the potential for fire in the electrical compartment. Boeing, the aircraft's manufacturer, did not immediately respond to a request for comment. United Airlines, presently the aircraft's only US-based operator, said it would immediately comply with the FAA's order and would work closely with the FAA and Boeing to return the aircraft to flight. It would accommodate passengers due to fly on its six 787s on other aircraft. Both incidents have involved the lithium-ion batteries that Boeing has installed in the new aircraft type to meet the unusually heavy demands of its power systems, which power parts operated hydraulically on traditional aircraft. Boeing chose the batteries in part because they are lighter than traditional nickel-based batteries. The FAA said it would not allow flights to resume until operators could prove the batteries were safe. The regulator said that, as well as continuing a review of the aircraft's safety announced on January 11 it would check whether Boeing had properly complied with special conditions put on its introduction of the novel battery type. While the FAA's directive covers directly only United's aircraft, the regulator said it would alert other regulators worldwide so that they could take parallel action. There are more than 800 orders still outstanding for the Dreamliner, which won more pre-launch orders than any aircraft in history. But it entered service three years late and has suffered continuing technical glitches. It remains unclear how fundamental the battery problem is and whether it reflects shortcomings in its manufacturing or a design problem. At the very worst, it could point to flaws in the aircraft's electrical system that will require a wholesale redesign. The two fires, however, could also have resulted simply from flaws in the manufacturing of the two batteries involved, with few wider implications. Teething problems are an accepted part of the introduction of almost any aircraft type as revolutionary as the 787, whose body is made mainly from carbon composites, rather than aluminium.