All Nippon Airways and United Airlines have found minor wiring damage on a total of three Honeywell-made emergency locator transmitters for Boeing 787s and have returned them to their manufacturer for inspection, the airlines revealed last week. The discoveries arose during inspections of the systems recommended by the UK’s Air Accidents Investigation Branch and mandated on Thursday by the U.S. Federal Aviation Administration in reaction to a July 12 fire aboard an Ethiopian Airlines 787 parked at London Heathrow Airport.
After removing the ELTs from its eight domestically operated 787s, ANA technicians found what the airline describes as a damaged battery wire on one of them. The airline found similar damage in spare ELTs not yet installed on airplanes. Meanwhile, ANA removed the ELTs from another 12 Dreamliners it operates on international routes and, after finding no damage, reinstalled them.
Although the airline reported its findings to Japan’s Civil Aviation Bureau, authorities haven’t yet determined whether the damage to ANA’s ELTs bore any relation to that found in the Ethiopian Airlines case.
United, meanwhile, found a single damaged wire associated with an ELT on one of its six 787s.
Last Thursday the FAA issued an airworthiness directive (AD) calling for either the removal or inspection of the ELTs. 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 location of the system and its associated wiring, mounted internally on 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.