By Dr. Thomas C. Accardi
Lithium batteries are currently classified as Class 9 materials under the Hazardous Materials Regulations (HMR) (49 CFR 180 185); however most lithium batteries and devices are currently classified as excepted from the Class 9 provisions of the HMR and therefore do not require a Notice to the Pilot in Command (NOTOC) to alert the crew of their presence on-board an aircraft.[i] Both the FAA and the National Transportation Safety Board (NTSB) have expressed concerns about the safe transportation of lithium batteries and the hazards lithium battery thermal runaways pose to both cargo and passenger carrying aircraft.
The NTSB issued safety recommendations regarding the dangers of lithium batteries following their investigation of a United Parcel Service (UPS) accident occurring on September 3, 2010 in the United Arab Emirates. The flight crew encountered a master warning indicating a fire on the main deck within 22 min. after departing Dubai International. Despite the flight crew’s attempt to quickly return to the airport, the aircraft crashed nine miles from the airport killing both crewmembers.
FAA’s Flight Standards Service is amending firefighting guidance material. New guidance reflects the challenges of combating lithium battery fires in full recognition of the increasing number of consumer Portable Electronic Devices (PEDs), powered by both lithium batteries (disposable) and lithium-ion batteries (rechargeable), that are being utilized and stored aboard passenger transport aircraft. [ii]
Flight Standards guidance to air carriers and crew members emphasizes the critical nature of small in-flight fires: “In flight fires left unattended, particularly those that are not readily accessible, may lead to catastrophic failure and have resulted in the complete loss of airplanes [emphasis added].”[iii] In addition, “fire tests conducted by various regulatory authorities have shown that fires allowed to spread into the aircraft’s overhead area may become uncontrollable in as few as 8-10 minutes.” [iv]
The FAA William J. Hughes Technical Center (WJHTC) in Atlantic City N.J. has been conducting testing on lithium-metal and lithium-ion batteries because of incidents in which these batteries have overheated, creating either a fire and/or explosion. In addition, these batteries are capable of self-ignition if a short circuit occurs, it is overcharged, or is heated to extreme temperatures, is mishandled or otherwise defective.[v] The severity of the risk associated with these batteries during a thermal runway poses serious dangers to passenger carrying aircraft because “a thermal runaway can reach temperatures above 1,100 degrees [and] these temperatures are very close to the melting point of aluminum (1,220 degrees F.)”[vi]
Validation is an important part of research. Ideally, research is both reliable (repeatable) and valid (measuring what was intended).[vii] In addition, for research to be useful in real world scenarios, the conditions found during routine operations should be duplicated as much as practical and possible in order for the results to be valid and applicable to routine flight operations.
The FAA’s WJHTC in Atlantic City compared the effectiveness of fire extinguishing agents for suppressing lithium battery fires and preventing thermal runaway propagation during 2013. They documented their findings in a report dated January 2014.[viii]. Two types of tests are reported in this report: “Tests were conducted to study and compare the cooling effectiveness of various agents on a hot plate followed by fixed amounts of the same agents applied to lithium-metal and lithium-ion cells induced into thermal runaway.”[ix]
The first testing protocol chosen by the WJHTC tested the “reaction time” of various agents to “react” with water followed by calculating an average temperature decrease which “was the main parameter to quantify the cooling effectiveness of the agents.”[x] It is interesting to note that the extinguishing agent was released in a predetermined amount “when the center thermocouple reached 160 degrees C.” [xi] It is highly likely that a lithium battery runaway fire in the cabin of a large transport aircraft will not be immediately located upon reaching a temperature of 160 degrees C. It is also likely that the fire will initially be hidden from flight attendant view and access. FAA Flight Standards recognizes that “hidden” fires are not readily accessible, may be difficult to locate and are more challenging to extinguish.”[xii] Furthermore, FAA Flight Standards guidance provides an example of a “hidden” fire as an aircraft overhead bin area.[xiii] Thus, the FAA’s WJHTC testing would benefit the aviation community in a more robust manner by introducing the real world criteria, consistent with FAA’s Flight Standards guidance material, which has greater validity than the protocol selected by the them which focused on the academic “reaction time of agents with water” and immediate [emphasis added] hot plate cooling agent determination taken from an initial temperature of 160 degrees C. considering that thermal runaway lithium battery fires can reach temperatures above 1,100 degrees very quickly.
The second test outlined in the WJHTC Jan. 2014 report was “performed to verify and demonstrate the agents’ cooling effectiveness previously found in the hot plate tests.”[xiv] Although the report states that “the tests were similar to the extinguishment of a laptop” the batteries were directly exposed to the agent instead of being enclosed in a battery case and the agent was applied after the first cell underwent thermal runaway.”[xv] Thus, no time delay, nor consideration of other combustible material encasing the PED was introduced nor considered in this testing protocol. In addition, the extinguishing agent was applied early – “after the first cell underwent thermal runaway.”[xvi]
Lithium batteries pose a significant threat to air transportation safety as acknowledged by the FAA and the NTSB. Additional testing should be conducted using realistic lithium battery fire scenarios, that allow for the likely time delays and discovery of “hidden” fires that have ignited combustible Class A material, should be developed followed by the testing of proposed extinguishing agents applied at the likely temperatures that would occur following the delayed discovery of the fire. The FAA and the aviation industry would significantly benefit from this additional research.
[i] FAA SAFO 10017
[ii] FAA Advisory Circular AC 120-80
[iv] Federal Aviation Administration Advisory Circular Ac120-80
[v] Federal Aviation Administration SAFO 10017
[vii] RTCA/DO200A, Appendix C
[viii] FAA/TC-13/53, Extinguishment of Lithium-ion and Lithium-Metal Battery Fires
[ix] Ibid, p. 7
[x] Ibid, p. 6
[xi] Ibid, p. 8
[xii] FAA Advisory Circular AC120-80, p. 3
[xiii] Ibid , p 3.
[xiv] Ibid, p. 10
[xv] Ibid, p. 10
[xvi] Ibid. p. 10
Dr. Thomas C. Accardi
Dr. Accardi served as a senior executive for FAA from 1987 until his retirement on Feb. 3, 2011. During that time, I led the FAA’s Aviation System Standards and the FAA’s Flight Standards Service in Washington. Aviation System Standards is an FAA headquarters organization based in Oklahoma City with field operations in eight locations responsible for instrument procedure development for FAA and the U.S. Army, operation of 30 turbo-jet and turbo-prop flight inspection aircraft and publication of all FAA aeronautical visual and instrument charts. His office also performed flight inspection services for NASA’s Space Shuttle, the National Science Foundation ice runway’s in Antarctica, and the DoD essential navigational facilities throughout the world as well as their combat contingency requirements. He was responsible for air carrier and general aviation safety throughout the United States serving as the Director of FAA’s Flight Standards Service from 1991-1997.