By Andrea Shalal-Esa
WASHINGTON (Reuters) - Honeywell International Inc
Investigators have been looking at several components, including a lithium manganese battery in the Honeywell emergency locator transmitter (ELT), as possible causes for the fire that caused extensive damage to a parked Ethiopian Airlines
Britain's Air Accidents Investigation Branch (AAIB), which is leading the investigation, may suggest temporarily removing the devices from the new Boeing Dreamliners while the probe continues, according to one source familiar with the probe who was not authorized to speak publicly.
A second source familiar with the investigation said the AAIB could issue a report in the next few days that includes some recommendations, without giving details on the proposals.
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 say 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.
Boeing says its highest priority is the safety of the new airplanes, and it is working closely with authorities to "understand exactly what happened - and why," wrote Randy Tinseth, vice president of marketing for Boeing Commercial Airplanes, in a blog posted on Wednesday.
"While the investigation continues, the 787 fleet is flying as normal. We're confident the 787 is a safe airplane and we stand behind its overall integrity," Tinseth wrote.
The AAIB's possible move to remove ELTs was first reported by The Wall Street Journal, which said that ELTs are not required for a plane to be certified for passenger flight.
The Journal, citing a person familiar with the matter, said the AAIB is preparing to ask the U.S. Federal Aviation Administration and the European Aviation Safety Agency to assess the necessity of the devices on 787s.
Officials at the FAA and U.S. National Transportation Safety Board (NTSB), which have both sent representatives to London to assist with the investigation, declined comment, referring queries to the AAIB.
A spokesman for the European Aviation Safety Agency said he had no information on the elements contained in the WSJ report
Honeywell said the report was based on "anonymous speculation" and said its officials had not been contacted by British or U.S. authorities involved in the investigation.
However, spokesman Steve Brecken said Honeywell always puts safety first and "would support an action like this as a precautionary measure if our team, or the AAIB and NTSB, determine it's necessary to do so."
Honeywell says it has built over 3,000 emergency beacons since they were first certified in 2005, and insists that it has not seen or experienced a single reported issue with them.
The FAA did issue a special airworthiness notice in 2009 in which it advised airlines to replace the antenna used by an earlier version of the Honeywell transmitter because it had failed in tests. Other global regulators published similar advisories at the time.
Asked about that notice, FAA spokesman Lynn Lunsford said there was no indication of fire risk linked to the earlier antenna problems.
The ELT, which is positioned in the upper rear part of the 787, sends a signal that leads rescuers to downed aircraft.
ELTs are largely redundant on most large jets since their routes are closely tracked by radar or air traffic controllers , except for long-range polar routes, said one aviation expert.
All planes also come with flight data recorders and voice data recorders that have sonar "pingers" that are activated in the event of a crash into water, when the ELT devices would not work anyway, said the expert.
The FAA also had no comment on the Journal's report that some FAA officials were arguing to shift jurisdiction for the fire investigation to the U.S. agency, since the Ethiopian plane was parked, rather than in flight, and was certified by the FAA.
(Reporting by Andrea Shalal-Esa; Additional reporting by Alwyn Scott in Seattle; Rhys Jones in London and Tim Hepher in Paris; Editing by Gary Hill, Tim Dobbyn and Leslie Adler)