A blaze on an Ethiopian Boeing 787 Dreamliner
plane which caused widespread disruption at Heathrow airport last week
has been linked to a lithium battery in its emergency beacon, air
accident investigators have revealed.
The
UK's Air Accidents Investigation Branch (AAIB) said the plane’s
emergency locator transmitter (ELT) caught fire and had shown
indications of disruption to the battery cells which ‘could provide the
energy for an ignition’.
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.