Boeing's recent guidance to passenger airlines advising that they not carry lithium-ion batteries in their cargo holds stems from the recommendations an industry-wide group has presented to the International Civil Aviation Organization (ICAO). It recognizes that fire suppression systems as currently certified cannot stop a fire involving bulk quantities of the batteries, said Boeing’s technical safety chief for fire protection.
Speaking on July 22 at the Air Line Pilots Association (ALPA) air safety forum in Washington, D.C., fire protection system specialist Douglas Ferguson described the process that led Boeing to send a “multi-operator memorandum” to airlines several days earlier. The memorandum advises against transporting bulk shipments of the rechargeable batteries used in many consumer devices until safer methods of packaging and shipping are developed. A number of U.S. airlines have already stopped such shipments.
“The significant question is—what has happened now that has caused us to provide this guidance to the operators, regarding the carriage of lithium batteries,” said Ferguson. “Briefly, it’s a recognition that unrestricted quantities of lithium batteries that are involved in a cargo fire, even with a Halon 1301 cargo fire suppression system, can still create hazards that would effect the continued safe flight and landing of the aircraft, particularly depending on the location, the type and quantity of batteries and the time required for a safe landing.”
The Boeing guidance stems from recommendations the International Coordinating Council of Aerospace Industries Associations (ICCAIA), an international grouping of aerospace associations, has presented to ICAO’s dangerous goods panel. In addition to Boeing, airframe manufacturers Airbus, Embraer and Bombardier participated in developing the recommendations under the ICCAIA umbrella. Separately, a multidisciplinary group that includes airframers will meet next week at ICAO headquarters in Montreal to consider a “performance-based” packaging standard for lithium batteries designed to mitigate the threat of fires.
A growing body of test data, including work done by the FAA’s William J. Hughes Technical Center near Atlantic City, N.J., has demonstrated that current cargo compartment fire-suppression systems cannot suppress or extinguish a fire involving bulk quantities of lithium batteries, Ferguson said.
“It’s important to note that the fire protection capabilities and the certification of our aircraft and our systems were developed considering the carriage of general cargo and not the unique hazards that are associated with dangerous goods, including lithium batteries,” Ferguson said. “What has happened is that testing has shown that there are higher rates of smoke production, flammable vapor, pressures and temperatures that occur with fires that involve lithium metal batteries, lithium-ion batteries (and) lithium polymer batteries than with ordinary Class A type combustibles, paper products for instance.”
Halon 1301, a liquified compressed gas used as a fire-suppression agent, “has a limited effectiveness,” Ferguson said. Testing by the FAA Technical Center revealed that “yes, Halon suppressed the flames, but it was not able to stop the propagation of the thermal heat from one battery affecting adjacent batteries, so there was a ‘thermal runaway’ in each battery that kept progressing throughout the packages.” The thermal runaway process also produces a large quantity of gas that pushes out the Halon, reducing its concentration, he added. And the increased temperatures and pressures in the cargo hold drive out smoke, potentially causing it to penetrate the occupied portions of the aircraft.
Responding to the July 17 Boeing memorandum, the Rechargeable Battery Association said it shares the manufacturer’s goal of ensuring the safe transport of bulk shipments of lithium-ion batteries by air, and looks forward to “continuing our engagement” with the airline industry and ICAO. But the association added that it “remains concerned that certification of aircraft fails to consider the unique hazards associated with the carriage of any dangerous goods, not just those associated with lithium batteries.”