Battery risks on aircraft garner closer scrutiny

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This February, the risk of personal electronic device (PED)-related battery fires on board aircraft became more evident after French safety authorities determined that a fire on board an Air France Boeing 777-200 was traced to a crushed Lithium–Polymer-type battery that fell into the seat mechanism. The event was deemed to be similar to a separate earlier fire on an Air France 777.

Regulators are now questioning whether the prevalent use of PEDs in-flight, as well as the widespread use of “copy-cat” lithium-ion batteries, may pose a greater risk to aviation than we might imagine.

A unique and unusual combination of factors can generate a PED battery-related fire on board aircraft. In a study on lithium-ion batteries, UL Laboratories points to “damaged separator due to external forces,” as a safety risk for these particular energy cells. 

It states, “An electrolyte leakage…could release toxic gases, or the deflagration of vented volatiles, which could lead to fire/explosion or an inability to operate the safety-critical device that is powered by a lithium-ion cell.”

The report emphasizes that three basic events must all happen for a detonation to occur, and lists those events as follows:

  • Ignition source: contact of the volatiles with a hot surface (or possibly the volatiles are already at a high temperature)
  • Fuel source: vented volatiles from the cell
  • Ambient air: oxygen needed to facilitate combustion (within the flammability limits)

The BEA (Bureau d’Enquêtes et d’Analyses pour la sécurité de l’aviation civile) specifically mentioned these conditions in its report on the latest fire incident aboard the Air France 777 flight, writing:

“An X-ray examination showed that the active elements in the battery had disappeared and the electronic control circuits had been destroyed. The crushing of the battery in the seat mechanism likely caused a short-circuit, leading to an increase in the internal temperature. The exposure of the lithium electrodes to the air caused a fire, and oxygen contributed to the combustion.”

Because powered seat controls and the electrical equipment that supports IFE is inherent to aircraft seat design – especially for first class and business seating loaded with comfort features – aircraft seats have the potential to inadvertently generate an ideal environment for these factors to converge.

Speaking to us as Chairman of the SAE seat committee and an FAA-DER, Zodiac Aerospace Seating VP of engineering Rakibul Islam shared his own insights into the likelihood of these occurrences, and potential fixes for legacy seats in the market, which may pose a greater risk than new seat designs.

According to Rakibul Islam, seat design standards established by the SAE committee that oversees aircraft seats could specify that gaps between seat elements must be avoided and wherever possible eliminated in the next revision of ARP-5526. Because they are built to these newly revised design guidelines, new herringbone and angled seating for business and first class are unlikely to allow PEDs to fall through the sides or between the cushions into areas of the seat frame where a lithium-ion battery could be crushed and ignite.

A corrective-action for existing legacy forward-facing seats, like the ones involved in the incident, might be as simple as closing any existing gaps with a panel of a para-pack nylon fabric, or alternate webbing, commonly used in seat structures for other applications and certified for flammability.  While Rakibul Islam agrees this is a retrofit which could be considered, he advises us that without reviewing the specific seat design he could not speak directly to the retrofit question. He did advise that this issue has not yet been a topic for discussion at the SAE Committee.

The promise of modern seat designs reducing these risks, and assurances from battery manufacturers and test facilities that a small percentage of batteries in the market pose a risk, might lead us to believe that incidents like that aboard this particular Air France flight are uncommon and there is no cause for concern.

Indeed, this particular incident is uncommon; but even regulators – including the UK CAA – believe there is good cause for concern.

While EASA has yet to reply to BEA’s recommendations on the above referenced report, the UK CAA has taken initiative to bring more industry and public awareness to this risk.

“We are trying to highlight the risks they pose to aircraft. We are working with airlines and airports to advise them of these risks. As part of this campaign, we have worked with the FAA to produce educational videos aimed at cabin crew, baggage handlers, and check-in staff,” says Richard Taylor, Corporate Communications at UK CAA.

The risk is especially high when passengers use illicit or off-brand battery units on their devices. Poorly made batteries may lack the necessary isolation (or have inadequate isolation) for the Lithium and catalyst elements which generate both power and heat. 

Various reports, written by UL and others, emphasize that batteries reaching high temperatures while charging pose a particular hazard. Aviation should also consider the risk of PEDs connected to seat power outlets. This is one area where the desire to provide customers something they want, could have unintended safety repercussions.

The challenge for aviation is its inability to control the lithium-ion battery market. That responsibility lies with device manufacturers.

Device manufacturers are also carrying out numerous debates and studies about the best way to reduce the risk of lithium-ion batteries and how to rein-in the “copy-cat” battery market.

Ironically, all of this could ultimately become a non-issue, not just for aviation but for the world. As CNET reported in 2013, scientists at The Department of Energy’s Oak Ridge National Laboratory (ORNL) have conducted extensive studies and are developing alternate compositions for Lithium batteries that could reduce their flammability risk, and actually increase their power-retention and service life. They might even reduce costs.

While these developments are ongoing, they have promise. How soon device manufacturers will adopt these technologies is an open question, and one aviation regulators cannot address. Higher-risk batteries, manufactured specifically for aviation applications, might benefit from such developments, but we will have to wait and see whether these new developments are adopted in future.

For now, the safest practice is for passengers to ensure their PEDs are powered by manufacturer-approved batteries, and that those batteries are in good condition.

Passengers will also want to ensure that any devices which are running hot are not used in flight; as a high operating temperature is a sign of potential battery degradation. Any devices plugged into seat-outlets should be unplugged during meal-times, while sleeping, or are other times when the devices will be unattended.

As with all cabin safety matters, passengers must take part to protect the delicate environment on board.

Separately, there remains deep industry concern about the transport of lithium-ion batteries in cargo holds. Reports that Malaysia Airlines MH370 – which tragically disappeared – was carrying a shipment of these batteries has forced the company to defend itself, and stress to media that the shipment was done in accordance with international standards.

A rule that would impose additional safeguards related to the transport of lithium ion batteries is making headway in the United States. You can track progress of the rule here; its publication date is set for 14 May. According to the FAA, as of 17 February 2014 a total 141 air incidents involving batteries carried as cargo or baggage have been recorded since 210 March 1991.

 

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