Shortcomings in design and certification ultimately led to the fire in a lithium-ion battery installed on a Boeing 787 jetliner that had just completed an intercontinental flight to Boston, the National Transportation Safety Board (NTSB) determined in its final report on the incident, which was released Dec. 1.
The investigation by the NTSB begs a bigger question, one that the Federal Aviation Administration has noted: large quantities of lithium-ion batteries – the ones found in laptops, tablets and cell phones – are shipped by air by manufacturers. A cell phone video of a laptop charging at LAX airport shows what happens when lithium-ion batteries overheat.
According to the FAA, which ran tests on the batteries utilizing shipping containers and conditions normally found on aircraft, “The explosive potential of lithium metal cells can easily damage (and potentially perforate) cargo liners, or activate the pressure relief panels in a cargo compartment.”
According to the FAA, “Either of these circumstances can potentially lead to a loss of Halon 1301, allowing rapid fire spread within a cargo compartment to other flammable materials. For this reason, lithium metal cells are currently prohibited as bulk cargo shipments on passenger-carrying aircraft.”
Several crashes have been attributed to lithium-ion batteries, including the crash of a United Parcel Service Inc. (UPS) cargo plane carrying 81,000 batteries, which caught fire and crashed after it left Dubai on Sept. 3, 2010. An Asiana Airlines cargo jet crashed on July 28, 2011, after the crew reported a fire on board that was thought to have been caused by lithium-ion batteries.
It took just one malfunctioning lithium-ion battery to ground Boeing’s Dreamliner planes for several months, after ground workers discovered smoke and flames coming from an auxiliary power unit lithium-ion battery in a Japan Airlines 787 that was parked at the gate at Boston Logan International Airport on Jan. 7, 2013. There were no injuries to any of the 183 passengers or 11 crewmembers who already had deplaned after flying from Tokyo's Narita Airport. The battery was manufactured by GS Yuasa Corp.
Early in the investigation, the NTSB said that the fire began after one of the battery’s eight cells experienced an internal short circuit leading to thermal runaway of the cell, which propagated to the remaining cells causing full battery thermal runaway. This condition caused smoke and flammable materials to be ejected outside the battery’s case and resulted in excessive heat and a small fire.
“The investigation identified deficiencies in the design and certification processes that should have prevented an outcome like this,” said NTSB Acting Chairman Christopher A. Hart. “Fortunately, this incident occurred while the airplane was on the ground and with firefighters immediately available.”
Because the APU and main lithium-ion batteries installed on the 787 represented new technology not adequately addressed by existing regulations, the FAA required that Boeing demonstrate compliance with special conditions to ensure that the battery was safe for use on a transport category aircraft.
Investigators said that Boeing’s safety assessment of the battery, which was part of the data used to demonstrate compliance with these special conditions, was insufficient because Boeing had considered, but ruled out, cell-to-cell propagation of thermal runaway (which occurred in this incident) but did not provide the corresponding analysis and justification in the safety assessment. As a result, the potential for cell-to-cell propagation of thermal runaway was not thoroughly scrutinized by Boeing and FAA engineers, ultimately allowing this safety hazard to go undetected by the certification process.
As a result of its findings, the NTSB is recommending that the FAA improve the guidance and training provided to industry and FAA certification engineers on safety assessments and methods of compliance for designs involving new technology.
“Through comprehensive incident investigations like this one, safety deficiencies can be uncovered and addressed before they lead to more serious consequences in less benign circumstances,” said Hart.
NTSB investigators also identified a number of design and manufacturing concerns that could have led to internal short circuiting within a cell.
As a result of the investigation, the NTSB made 15 safety recommendations to the FAA, two to Boeing, and one to GS Yuasa.
“The aviation industry is continually benefiting from technological advances, and we are hopeful that the lessons learned in this investigation will further enhance the industry's ability to safely bring those innovative technologies to market,” said Hart.
Federal Regs Updated for Lithium-Ion Batteries
The U.S. Department of Transportation (DOT) earlier this year issued new standards to strengthen safety conditions for the shipment of lithium cells and batteries. These changes, some of which focus specifically on shipments by air, will better ensure that lithium cells and batteries are able to withstand normal transportation conditions and are packaged to reduce the possibility of damage that could lead to an unsafe situation.
“Safety is our number one priority, and this rule provides an additional layer of protection to the shipment of lithium batteries, which we all depend on daily to power our phones and our laptops,” said Transportation Secretary Anthony Foxx. “[This is] part of our ongoing work to improve safety for all travelers, including those who travel with or ship lithium batteries.”
NBC News did a special report on Dec. 2 that showed video of the FAA testing of lithium-ion batteries.
The rule provides a greater level of consistency with international standards, including the International Civil Aviation Organization’s (ICAO) Technical Instructions for the Safe Transport of Dangerous Goods by air.
“Our continuing efforts to harmonize U.S. Hazardous Materials Regulations with international standards improve consistency in procedures and terminology when shipping lithium batteries around the globe,” noted PHMSA Administrator Cynthia L. Quarterman.
The final rule:
- Enhances packaging and hazard communication requirements for lithium batteries transported by air;
- Replaces equivalent lithium content with Watt-hours for lithium ion cells and batteries;
- Adopts separate shipping descriptions for lithium metal batteries and lithium ion batteries;
- Revises provisions for the transport of small and medium lithium cells and batteries including cells and batteries packed with, or contained in, equipment;
- Revise sthe requirements for the transport of lithium batteries for disposal or recycling;
- Harmonizes the provisions for the transport of low production and prototype lithium cells and batteries with the ICAO Technical Instructions and the International Maritime Dangerous Goods Code; and
- Adopts new provisions for the transport of damaged, defective and recalled lithium batteries.
In response to the rule, the Air Line Pilots Association, Int’l (ALPA) said it was pleased that the U.S. Department of Transportation’s Pipeline and Hazardous Materials Safety Administration (PHMSA) issued what it called “overdue safety regulations” for transporting lithium batteries by air and has taken steps to harmonize existing U.S. rules with international standards.
“While ALPA is still conducting a detailed review of the new regulations, PHMSA’s action is recognition of the serious risk that unregulated shipments of lithium batteries pose to all who depend on air transportation. We look forward to continuing to work with the regulator to ensure that air transportation is fully safeguarded against fire and other safety hazards that are associated with inadequately protected air shipments of lithium batteries.”