Official report throws light on 787 Dreamliner fire

The plane, operated by Ethiopian Airlines, was remotely parked at the time and there was no one on board, but the incident resulted in the temporary closure of both runways at the airport.

The lithium battery powered an emergency locator transmitter, installed to help locate missing aircraft.

British aviation authorities called Wednesday for a safety review of lithium batteries used in commercial aircraft, saying they were believed responsible for a 2013 fire on an Ethiopian Airlines aircraft at London’s Heathrow.

The report by Britain’s Air Accidents Investigation Branch (AAIB) says the fire, previously determined to have started from a short circuit in a small lithium battery powering an electronic emergency beacon, was fed by the epoxy resin in the composite plastic that forms the plane’s fuselage.

“Gaining access to the ELT, which may require the removal of cabin ceiling panels, and getting close enough to make the use of a fire extinguisher effective, would be challenging”, the report said.

An area of fuselage measuring 9.5 sq. meters (102 sq. feet) was damaged in the fire, which also destroyed carbon-fiber insulation blankets designed to minimize heat loss and suppress noise.

In the immediate aftermath of the incident, FAA instituted several safety measures, including inerting the ELT.

Among new recommendations issued in the report, AAIB said the FAA, EASA and Transport Canada should assess the circuit protection offered by the Honeywell ELT battery, to determine whether the ELT/battery design was adequate to mitigate against external short-circuits or unbalanced discharges.

The AAIB also wants Boeing to speed up tests on how toxic smoke from an ELT battery fire would spread through the state-of-the-art system that controls cabin air in the Dreamliner.

In a statement, Boeing spokesman Paul R. Bergman said: “The final report by the AAIB is extensive and thorough, and we appreciate the effort put into the investigation”.

“We are committed to a process of continual improvement of our airplanes”, Chicago-based Boeing said in an emailed statement, adding that changes need to be reviewed with “great care” to avoid unintended consequences.

Boeing noted that the U.S. FAA had already recommended inspections of Honeywell RESCU 406 ELTs across all models of aircraft, and that “operators have confirmed to the FAA that all in-service ELTs are in compliance with federal regulations”.

“The safety of passengers and crew members who fly aboard Boeing airplanes is our highest priority”.