The fire that caused significant damage to an Ethiopian Airlines 787 Dreamliner sitting on the tarmac of London's Heathrow airport last week is now officially being blamed by British authorities on batteries — but not the same ones that led to the 787's months-long grounding earlier this year. This time, the focus is on an emergency locator transmitter (ELT) manufactured by Honeywell, which uses lithium-manganese batteries and sits in the upper rear portion of the aircraft's fuselage.

ELTs, found on commercial and private aircraft around the world, are designed to emit a signal that can help locate a downed aircraft after a crash. The specific model found on the 787 is also used on a variety of other aircraft, so having the fire occur on a Dreamliner — a plane already suffering from a damaged reputation thanks to previous fires — appears to be an unlucky coincidence.

The Dreamliner isn't the only plane using this part

In the short term, the UK's accident investigation bureau, AAIB, is recommending that the 787's ELT be rendered "inert" until it can be properly fixed, noting that if the fire had occurred in mid-air, crew would have had a very difficult time putting it out considering its unusual location. The bureau is also recommending that all lithium battery-powered ELTs be checked out and revised for safety where necessary.

Fires and explosions involving lithium batteries are rare, but not unheard of — stories of smartphones combusting in pockets appear on occasion, and it stands to reason that they same rules of physics apply to a battery inside of an aircraft component. "Detailed examination of the ELT and the possible mechanisms for the initiation and sustaining of the fire in this aircraft continues," the AAIB says.