All Nippon Airways, the largest operator of the Boeing 787, says it has discovered minor damage to battery wires on two of the emergency locator transmitters (ELT) that are used on the aircraft.

The carrier has conducted inspections on its 787 fleet in the wake of a fire on an Ethiopian Airlines 787 on July 12, that is believed to have originated in an ELT. An ANA spokesman tells Aviation Week that the airline conducted the inspections voluntarily, before Japanese regulators issued an airworthiness directive on July 26.

ANA workers removed ELTs from eight domestically operated 787s and found a small amount of battery wire damage in one of them. There was also minor damage in one spare ELT that had not been installed on a 787, the spokesman says.

The damaged ELTs will be sent to their manufacturer, Honeywell, for inspection and ANA has reported its findings to Japan’s Civil Aviation Bureau.

ELTs were also removed from ANA’s 12 787s that are operated internationally, but were reinstalled after the checks were completed.