The ELT is an emergency beacon used to give emergency services and authorities an accurate location for a plane following a crash.
Boeing’s hi-tech flagship ‘plastic plane’ has been dogged with faults since launch and already been grounded worldwide because of battery problems elsewhere in the plane.
The new investigators’ report notes that the emergency beacon in the stricken aircraft contained a set of lithium-manganese dioxide-based chemical batteries which allow it to operate in an emergency.
It said: ‘Detailed examination of the ELT has shown some indications of disruption to the battery cells.
‘It is not clear however, whether the combustion in the area of the ELT was initiated by a release of energy within the batteries or by an external mechanism such as an electrical short.’
But it stresses: ‘In the case of an electrical short, the same batteries could provide the energy for an ignition and suffer damage in the subsequent fire.’
The AAIB today called on the Federal Aviation Administration (FAA) to begin efforts to make the ELT ‘inert’ on all 787 aircraft until the safety of the device can be explored further.
British Airways has taken delivery of the first of its 24 Dreamliners, while Virgin Atlantic is due to receive the first of its 16 Dreamliners in September next year.
Investigators also called on the FAA to conduct a safety review of installations of similar Lithium-powered ELTs in other aircraft.
In a statement, Boeing described the recommendation for the beacons to be immobilised as ‘a precautionary measure’ adding: ‘The safety of passengers and crew members who fly aboard Boeing airplanes is our highest priority.
