UK Blasts Lithium Metal Batteries

The British AAIB (Air Accidents Investigation Branch) has released their preliminary findings addressing the onboard fire incident relating to an Ethiopian Airlines B-787 parked on the LHR tarmac last year.
     The incident, classified “serious,” happened on July 12th at 15:34 h UTC to a Boeing 787-8 operated by Ethiopian Airlines while parked on the tarmac at London–Heathrow airport.
     The onboard fire, which started in the rear part of the cabin, consumed the crown of the fuselage, roughly located between the two rear doors on the left and right sides of the aircraft.
     Because the door areas are most exposed to stress and varying forces, the fuselage structure in that part of the aircraft is more robust than in other parts of the aircraft. The same goes for the pressure bulkhead, which seals the rear part of the aircraft and is imperative for maintaining cabin pressure.
     Since this incident happened soon after B-787 models were involved in incidents relating to their Lithium-Ion starter batteries, rumors spread immediately that this incident may have been Lithium battery related.
     Of course IATA, PRBA, and some other stakeholders slammed those rumors as “totally unfounded and without basis.”
     The latter, however, turned out to be premature.

AAIB Assails Runaway Lithium Batteries

     As AAIB Bulletin S4/2014 outlines in detail, a Lithium-Metal battery installed in a so-called ELT, an Emergency Location Transmitter started the Ethiopian fire.
     This device is intended to notify rescue authorities of the exact location of the aircraft in case of an emergency.
     The ELT in question, a Honeywell RESCU 406AFN, was located, as mentioned, in the aft fuselage crown above the passenger cabin.
     It may be noteworthy to explain that these devices typically operate in a non-powered silent (or “armed”) mode, not consuming any power unless activated in case of an emergency.
     The AAIB investigation showed that the internal battery back of the ELT had shown “severe disruption, exhibiting evidence of a very high-energy thermal event, consistent with having experienced a thermal runaway. All five cell cases had been breached and burnt battery material had been ejected into the battery compartment outside the ELT case.”

Causes

      The cause for the thermal runaway of this ELT Lithium-Metal battery was proven to be improper wiring, which likely took place upon installation of the ELT, when the aircraft was built in Boeing’s Seattle plant. For the record, there were no maintenance records relating to the ELT for the incident aircraft.
     While the exact accident scenario—for which the British AAIB has identified five likely sub scenarios—is under further investigation, all ELTs of the aforementioned type have been subjected to a mandatory safety inspection.
     It is also noteworthy that a review of the actions undertaken by the ELT manufacturer (Honeywell) and the assembler (Instrumar ELT) showed that a total of 26 ELT’s returned for inspection between July 2013 and February 2014 exhibited trapped wires.
     Based on the findings at the beginning of the investigation, the UK AAIB issued Safety Recommendations 2013-016 and 2013-017 recommending that the FAA as certifying authority for the B-787 aircraft model mandate inerting of the ELT types in question, and conduct a safety review of the ELT technology currently in use on other aircraft types.
     In response, the U.S. FAA issued Airworthiness Directive 2013-15-07 on July 26, 2013, requiring that within a 10-day timeframe the ELTs in question were either removed or inspected and corrective action taken. A subsequent service bulletin issued by Honeywell followed while the FAA undertook an extensive review of the ELT technology currently in use.
     Effective May 2014, the wiring of the Honeywell/Instrumar ELT’s has been changed so that further trapping of wires can be ruled out.

Lithium Metal Banned January 2015

      While a large part of the AAIB’s conclusive, although preliminary report deals with the aspects of aircraft equipment certification and the certification of Lithium batteries for use aboard aircraft, this investigation is far from over, and the AAIB subsequently issued Safety recommendation 2014-20 recommending that the FAA “develop enhanced certification requirements for the use of Lithium-Metal equipment in aviation.”
     The aforementioned measures undertaken by the UK AAIB, the US FAA, Honeywell/Instrumar, and Boeing will almost certainly prevent a similar incident or accident scenario from happening.
     However, at this point it must be explained that the battery type in question—Lithium-metal—will be banned from transportation as such starting January 1, 2015, according to decisions recently made by the ICAO DGB based on tests undertaken by the FAA and the volatile characteristics of the Lithium-metal battery technology.
     Emphasis is on “Lithium-metal batteries transported as such” (e.g. only the battery by itself) being banned from transport aboard passenger aircraft.
     Lithium-metal batteries either packed with equipment or installed in equipment will continue to be permitted for transport aboard passenger carrying aircraft from 2015 onwards.

Permitted But Prudent?

      Given the large scale of devices, gadgets, and toys incorporating or being shipped with such Lithium-metal batteries, and given the fact that such devices, toys, and gadgets are not subject to the stringent requirements of aircraft equipment, one must ask whether the permissibility of transporting Lithium-metal batteries aboard passenger-carrying aircraft is prudent.

Weighing Risks

      However, in all fairness it must be said that a ban of Lithium metal batteries packed with or installed in equipment would have serious implications on the global supply chain and would detrimentally affect everyone, from manufacturers to distributors and consumers alike.
     Given the rather complicated provisions and requirements pertaining to the shipping of Lithium batteries of any type, one obvious course of action would be to do away with the exemption from the formal dangerous goods training requirements for shippers of so-called “part II” or “excepted” batteries, since all stakeholders have identified training to be a key prerequisite to maintain a safe regimen for the shipping of dangerous goods by air.
     That being said, authorities will have to weigh carefully the risks associated with the transport of Lithium-metal batteries against the inconveniences within the supply chain.
Jens

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