Government and industry groups are eyeing more stringent safeguards or possible bulk-shipment bans on lithium-chemistry batteries ahead of an ICAO Dangerous Goods Panel (DGP) meeting next month. 

                                                                       

The DGP sets the technical standards defined in ICAO Annex 18, “Safe Transport of Dangerous Good by Air,” which member states are required to follow.

Included the DGP meeting will be the input from ICAO’s multidisciplinary lithium-battery transport group, which is recommending a slate of mitigations, including: risk assessments for battery shipments; a reduced “state of charge” for batteries being shipped; restrictions on carrying lithium-ion batteries in passenger-aircraft holds; and requiring enhanced documentation, labeling and packaging for the lithium-battery shipments. DOT, FAA and the Pipeline and Hazardous Materials Safety Administration held a meeting in mid-September to get input from industry and the public on the various proposals ahead of the ICAO meeting.

ICAO Cargo Ban?

While ICAO standards and recommended practices already ban passenger aircraft from carrying bulk shipments of lithium-metal batteries in the cargo hold, the same does not apply to all-cargo aircraft, or to shipments of lithium-ion batteries for passenger and all-cargo aircraft. Lithium-metal batteries—typically non-rechargeable and used in devices such as cameras and watches—contain metallic lithium that is not extinguished by the Halon fire suppressant used in aircraft cargo holds.

Lithium-ion batteries are usually rechargeable and power devices such as mobile phones and laptop computers. While Halon will suppress flames from a lithium-ion battery fire, the agent is “marginally effective in protecting cargo shipments due to its inability to prevent cell-to-cell thermal-runaway propagation,” according to the Air Line Pilots Association (ALPA). ALPA is calling for more testing on the number of lithium-ion batteries that can be shipped safety given the capabilities of the onboard fire-suppression systems.

The flammable vapors from lithium-ion batteries that vent after a thermal runaway—which might be caused by damage to a cargo pallet or other heat-generating events—can also accumulate in cargo holds, possibly causing an explosion. FAA testing in a 737 cargo hold showed that as few as seven fully-charged type 18650 lithium-ion batteries were needed to produce an explosion that ruptured a cargo container. DOT notes that the “production of flammable gases from a lithium ion battery increases with state-of-charge, particularly at or above 50%,” and that cells are typically shipped with a state-of-charge of 50% or more.

Debate at the DGP meeting will include: calls to temporarily ban the shipment of lithium-ion batteries on passenger aircraft until mitigations are deployed; shipping only batteries with a lower state-of-charge; and coming up with performance-based criteria for cells and packaging to mitigate the effects of a potential thermal-runaway condition.

Performance-based criteria could include assurances that no hazardous flames or hazardous fragments can exit the packaging after a cell failure, or that the external surface temperatures or the amount of flammable gases produced after a cell failure remain within certain limits.