The U.S. Federal Aviation Administration on Thursday issued an airworthiness directive (AD) calling for either the removal or inspection of the Honeywell fixed emergency locator transmitter (ELT) in Boeing 787s. The AD stems from the July 12 fire aboard an Ethiopian Airlines 787 parked at London Heathrow Airport and follows a separate recommendation from the UK Air Accidents Investigation Branch (AAIB) that operators of Boeing 787s disable the systems.
The directive, which covers the 68 Boeing 787-8s now in service, noted that continued investigation into the event could result in further rulemaking and expand to other ELTs on various other aircraft.
The AAIB found that most of the fire damage to the Ethiopian 787 occurred at or near the location of the system and its associated wiring, mounted internally on the structure near the skin of the rear fuselage section. The AAIB further noted that no other systems in the area contain enough stored energy to start a fire.
Detailed examination of the ELT has shown some indications of “disruption” of the battery cells, said the bulletin. However, the AAIB hasn’t concluded whether the damage resulted from a release of energy within the batteries or and external mechanism such as an electrical short.