U.K. investigators are recommending deactivation of Honeywell's Emergency Locator Transmitter (ELT) system on all Boeing 787 aircraft, following a technical examination of a 787 that caught on fire last week at London's Heathrow Airport.
The 787, operated by Ethiopian Airlines, was parked in a remote location at the time of the fire, with no passengers onboard, while all of the aircraft's systems were not activated. U.K.'s Air Accidents Investigation Branch (AAIB) examined the fire-damaged aircraft, and found the most extensive heat damage in the upper portion of the rear fuselage, near the location of the ELT system.
According to AAIB, there are no other systems within that vicinity, and the ELT contains stored energy capable of initiating a fire in the area where the most damage was found, even while the aircraft is not powered up. Investigators believe the fire that erupted was likely caused by the ELT.
"Had this event occurred in flight it could pose a significant safety concern and raise challenges for the cabin crew in tackling the resulting fire," AAIB said in a statement.
AAIB issued two safety recommendations for FAA, stating that the agency should make ELT systems in all Boeing 787 aircraft "inert until appropriate airworthiness actions can be completed." Authorities also recommend FAA conduct a safety review of installations of lithium-powered ELT systems in other aircraft types as well.
Honeywell's ELT is designed to broadcast a signal in the event of a crash to help rescuers locate the aircraft. The batteries in the system are separate from the aircraft's electrical power, so that in the event that power is lost, the emergency transmissions would still go through.
The fire was a big setback for Boeing, after the worldwide fleet of 787s were grounded earlier this year due to separate incidents involving the overheating of the aircraft's lithium-ion battery system. Ethiopian Airlines was the first carrier to return its Dreamliner to service following the grounding.
FAA has not responded to the safety recommendations. Boeing issued a statement supporting both recommendations from AAIB, calling them "reasonable precautionary measures to take as the investigation proceeds." Officials from Boeing and FAA are both participating in the ongoing investigation.