The UK Air Accidents Investigation Branch recommended Thursday that operators of Boeing 787s disable the airplanes’ Honeywell-made emergency locator transmitter following last Friday’s fire aboard a parked Ethiopian Airlines Dreamliner at London Heathrow Airport. It also asked the U.S. Federal Aviation Administration to conduct a safety review with other regulatory authorities of lithium-powered ELTs in other aircraft models.
The recommendation would affect 68 Boeing 787s now in service and all Dreamliners delivered until the time regulators institute procedures for a permanent fix.
In a statement issued immediately following the release of the AAIB’s bulletin, Boeing expressed its support for the UK authority’s decision.
“As a party to the investigation, Boeing supports the two recommendations from the UK Air Accidents Investigation Branch, which we think are reasonable precautionary measures to take as the investigation proceeds,” said Boeing. “We are working proactively to support the regulatory authorities in taking appropriate action in response to these recommendations, in coordination with our customers, suppliers, and other commercial airplane manufacturers. We are confident the 787 is safe and we stand behind its overall integrity.”
Although it has not conclusively identified the ELT, or its lithium-manganese battery, as the original source of the fire, the AAIB found that the most fire damage coincides with the 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.
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.
In a statement sent to AIN yesterday, Honeywell said it has not seen or experienced a single reported “issue” involving its ELT, a system introduced in 2005.