Honeywell endorses AAIB proposals on 787’s lithium-powered transmitters

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Honeywell says it supports two recommendations issued today by the UK agency investigating the Boeing 787 fire at London Heathrow airport. The supplier makes the Rescu406AFN emergency locator transmitter (ELT) system that is currently the focus of investigators looking for the cause of the 12 July fire in the upper aft fuselage area of the Ethiopian Airlines 787.

The UK Air Accidents Investigation Branch (AAIB) recommends that the US Federal Aviation Administration (FAA) move to render the ELT system inert across the 787 fleet.

"As a safety-first focused company, we support the AAIB's proposal and will offer assistance to Boeing and the airlines if needed," Honeywell says.

Honeywell also cautions that it is premature to draw conclusions, but the AAIB's recommendation to temporarily inert the ELTs on 787 is "prudent".

The company also endorsed the AAIB's second recommendation, which suggested the FAA launch a safety review on all lithium-powered ELTs.

The Honeywell Rescu406AFN system, like many competing transmitters, is powered by lithium batteries. The internal chemistry of the battery is lithium manganese dioxide, which is usually considered less volatile than the lithium cobalt dioxide batteries that power the 787's auxiliary power unit and main batteries.

The AAIB is continuing to investigate to find the root cause for the fire. The branch notes in its initial findings that the ELT is the only system in the area damaged by the fire that contained an internal power source that could have provided an ignition.

The empty 787 was parked and unpowered at the time of the fire.