Transporting lithium batteries in the bellies of commercial jets is more hazardous than previously recognized, with federal tests revealing that just a handful of burning power cells can overwhelm typical onboard cargo safety and fire-suppression systems.
Results from recent Federal Aviation Administration laboratory testing, combined with the latest risk-reduction proposals from battery makers, highlight a shift in the debate over bulk shipments of highly flammable lithium batteries. International regulators and aviation industry officials increasingly worry about the dangers, and they are developing far-reaching packaging restrictions for airborne carriage of the ubiquitous power sources.
The deliberations aren’t focused on lithium batteries carried by passengers into airline cabins to power cellphones, tablets and other portable consumer electronics.
Reports released by the aviation arm of the United Nations, which is slated to consider tighter standards later this fall, document those escalating concerns. An FAA paper presented to the U.N.’s International Civil Aviation Organization in late July, for example, concluded that less than two dozen rechargeable lithium-ion batteries can emit explosive gases powerful enough to breach cargo panels and overwhelm typical firefighting systems in the belly of a Boeing 737 jetliner.
Depending on cargo hold pressures, accumulation of gases and internal battery power levels, FAA experts determined that such compartments can even be compromised by the uncontrolled ignition of eight or even fewer batteries.
In an email Friday, an FAA spokeswoman said the tests demonstrated that the usual concentration of firefighting halon gas—typically used to fight cargo fires and the gases they produce—“is too low to prevent the ignition of these flammable gases” once heat transfers quickly from one lithium battery package to another in what engineers refer to as a “thermal runaway.”
According to an ICAO staff report presented at the same July meeting of industry, government and pilot-union experts convened by the U.N. organization, such a potentially catastrophic chain reaction can begin to occur at temperatures above 150 degrees Celsius. The staff report also said the current normal concentration of halon discharged in the event of a fire needs to be doubled “to prevent an explosion from these gases.”
In some FAA tests, lithium battery fires have been shown to produce temperatures exceeding the melting point of aluminum.
Over the past nine years, lithium batteries have been implicated in intense, quickly spreading airborne fires that brought down two jumbo freighters and killed their crew, as well as an earlier fire that destroyed a large cargo aircraft after it landed. In the case of a United Parcel Service Boeing 747 that crashed in Dubai in 2010, flight controls were severely damaged less than three minutes after the crew received an initial fire warning. The cockpit rapidly filled with so much smoke that the pilots couldn’t monitor their instruments, change radio frequencies or see anything through the windshield.
The rechargeable battery industry’s main trade group, known by the acronym PRBA, submitted a separate report in July broaching something it has balked at for years: significantly reducing the level of internal charge of batteries shipped by air. One of the association’s charts suggested exempting batteries with less than 30% of maximum charge from new packaging rules, because the volume of explosive gases decreases with a reduced level of charge.
Some battery officials and electronics industry representatives, however, have asserted such a reduced charge can result in battery damage and other negative consequences. Some bulk shipments can include many thousands of lithium batteries.
According to a March report prepared by the battery association, more than 5 billion individual lithium ion cells are projected to be produced globally in 2016, nearly doubling from 2008 totals. Multiple cells often are assembled to create a single battery. More-flammable lithium metal batteries, as well as larger and more powerful types of batteries designed for electric cars, sometimes also are shipped on planes.
Given such growth, FAA officials and other hazardous materials experts at the Transportation Department have scheduled a public meeting in Washington later this month to consider the U.S. position on further safety enhancements. According to the formal notice for the session, lithium batteries are “capable of self-ignition” due to a “short circuit, overcharge, exposure to extreme temperatures, mishandling, or a defect.”
In October 2014, an ICAO advisory group recommended sweeping changes in fire-retardant packaging and other safeguards, but put off specific standards. At the end of the July meeting, the same experts agreed on general guidelines for longer-term packaging changes but still left many details open for additional discussions.
There wasn’t any consensus on short-term safety enhancements, prompting leaders of pilot unions to decide to push for a binding global ban on shipping any lithium batteries as cargo on passenger aircraft.
Meanwhile, Boeing and European plane maker Airbus Group SE have said current jetliner designs weren’t intended to withstand the extensive fires and explosive gases lithium batteries can produce. Even before those warnings, a number of airlines around the globe voluntarily banned bulk shipments of such batteries on passenger aircraft, and some also extended the ban to freighters.
In July, the union representing most British airline pilots urged airlines and passengers to take extra precautions to ensure that lithium ion batteries, as well as the personal devices they power, are carried only in aircraft cabins “where a buildup of gases or fire can be tracked more easily” than in cargo holds.
A position paper submitted to ICAO by the International Federation of Air Line Pilots’ Associations in July argued that “any new performance packaging standards must be applied to both passenger and all-cargo operations.” Pilot representatives also said in the document that internal power levels for rechargeable batteries shipped by air should be set at “a level significantly below that” shown to be safe in tests.