Emergency crew stands near the tail section of a Boeing 787 Dreamliner, operated by Ethiopian Airlines, which caught fire at Britain's Heathrow airport in this July 12, 2013 still image taken from video.
U.K. air accident investigators are recommending that all Honeywell emergency transmitters should be temporarily disabled on Boeing 787s following a fire last week at London's Heathrow Airport.
The Air Accidents Investigation Branch said Thursday that the greatest damage to the parked Ethiopian Airlines Dreamliner occurred in the vicinity of the aircraft's emergency locator transmitter.
Investigators said it was not clear if the fire was caused by the transmitter's batteries or a short near or around the transmitter, but recommended that the Federal Aviation Administration disable Honeywell's transmitters in Boeing 787s "until appropriate airworthiness actions" can be carried out.
Boeing said Thursday that the beacon could be removed easily. Honeywell said it backed the AAIB's recommendation, but added that it was too soon to draw conclusions.
Investigators also recommended that the FAA and other regulators carry out a safety review of lithium-battery powered transmitters in other types of aircrafts.
Honeywell's emergency beacons are in use on a wide range of airplanes.
The latest fire on board Boeing's new composite airliner comes on the heels of a three-month grounding linked to problems with much larger lithium-ion batteries on the plane.
Sources close to the investigation told Reuters that it is turning out to be more complex than initially expected given that the fire caused severe damage to the upper portion of the jet's rear fuselage. As in the earlier probe, investigators are finding it difficult to pinpoint the cause of the fire.
A spokeswoman for the AAIB on Wednesday reiterated that Honeywell's ELT was one of several components being looked at in detail as part of the investigation, but said it would be premature to speculate on the causes of the incident.
AAIB has declined to identify any other components that might be under scrutiny.
Emergency beacons made by Honeywell International Inc can be simply removed from the Boeing 787 in about an hour, Boeing said.
"The emergency locator transmitter (ELT) can be simply removed and the task takes on the order of one hour to perform," said Boeing spokesman Marc Birtel.
He said the device's main purpose is to alert and guide rescue crews to the location of an airplane in the event of an accident, but the equipment was not required as part of the airplane design.
"It is not a U.S. Federal Aviation Regulation requirement, but it is required by some foreign regulators for their airlines or their airspace," Birtel said.
Reuters and The Associated Press contributed to this report.
First published July 18 2013, 8:48 AM