After last month's fire involving the emergency locator transmitter (ELT) on a Ethiopian 787 in London, the FAA and other regulatory agencies around the world have ordered that these ELTs be deactivated, inspected, or removed. The ELT on that aircraft was manufactured by Honeywell, which has produced about 6,000 ELTs for use in aircraft around the world.
A recent airworthiness directive from Transport Canada airworthiness directive (AD), which takes effect on 26 August 2013, has gone a step further, requiring that Honeywell ELTs on a variety of aircraft be inspected by the end of 2013. Transport Canada stated that the AD was issued as a precautionary measure to address the possibility of a fire due to wiring installation discrepancies of the ELT system. Depending on the outcome of the AAIB investigation, Transport Canada may revise the AD or mandate additional corrective actions.
Previous directives from the UK and US authorities were limited to the 787. This latest Canadian AD covers a much wider range of aircraft, including the Boeing models 717, 727, 737, 747, 757, 767, 777, 787, MD11, MD80 and MD90; and the Airbus models A300, A310, A320, A321, A330, A340 and A380.
Other countries following Canada's lead
The European Aviation Safety Agency (EASA) has also adopted the Canadian AD. According to various media reports, the FAA also plans to issue a similar AD for US-registered aircraft.
Why ELT fires are potentially catastrophic
As was described in some detail in an earlier AirSafeNews.com article on the Ethiopian 787 event, fire caused by an ELT would be particularly worrisome because these devices, unlike other systems such as engines and auxiliary power units, do not come equipped with fire suppression systems, and they are typically located in parts of the aircraft that are inaccessible from the cabin. In the event of an in flight fire, it may not be possible to put out the fire, and it may spread to other parts of the aircraft.
In the event of an onboard fire, typical emergency procedures include landing at the closest suitable airport, but if the fire occurred if the aircraft were far from a a suitable airport, which would be the case for many transatlantic or transpacific flights, passengers and crew could be exposed to large amounts of smoke and fumes for a significant amount of time.
In such a situation, emergency oxygen systems may not have been useful for passengers since these systems are typically designed to supply passenger with a combination of oxygen from the emergency oxygen system and ambient air from the cabin, including any smoke or fumes that are present in the cabin.