Fears are growing that the Dreamliner 787 will not be returning to service as quickly as hoped after Japanese and US air safety inspectors found no fault with the battery.
The battery was initially believed to be the problem with 787s owned by two Japanese airlines.
But according to BBC reports, Japan's transport ministry said inspections have now switched their focus to the electrical system that monitors the aircraft's battery voltage, charging and temperature.
The news has dashed hopes of a quick fix for the problem, which has seen all 50 787s in service grounded.
Aviation experts say the latest findings meant it could be difficult to identify the cause and Boeing could be forced to do a major re-design.
Boeing currently has orders for more than 800 Dreamliners. Thomson and British Airways are both major customers for the new aircraft.
Safety investigations started after one of the 787s operated by All Nippon Airways was forced to make an emergency landing when its main battery overheated and a battery in a Japan Airlines 787 caught fire while parked at Boston's Logan International Airport.
by Bev Fearis
Tuesday, January 29, 2013