MIAMI — The National Transportation Safety Board (NTSB) issued a series of recommendations related to the evaluation and certification of the lithium-ion batteries for use in aircraft systems on Thursday. The report was prompted, and is par of, the ongoing investigation of the battery fire aboard a Japan Airlines Boeing 787 at Boston Logan International Airport back in January 2013.
In the release, investigators noted that the battery involved in this incident showed evidence of not just an internal thermal runaway, but that “unintended electrical interactions occurred among the cells, the battery case, and the electrical interfaces between the battery and the airplane.” Their 12-page safety recommendation letter stated that the processes used in 2006 so support the certification of the 787’s lithium-ion battery were inadequate, in part, because there is no standardized thermal runaway test to most accurately reflect how the battery would perform when installed and operated on an in-service airplane.
Furthermore, the NTSB said that because there is no thermal runaway test on lithium-ion battery designs on 787s currently in service, it might not have adequately accounted for the dangers associated with internal short circuiting.
In its examination of the challenges associated with introducing newer technologies into already complex aircraft systems, the NTSB said that including subject matter experts outside the aviation industry “could further strengthen the aircraft certification process” by ensuring both the FAA and the aircraft manufacturer have access to the most current research and information related to the developing technology.
To address these issues, the NTSB asked the FAA to perform the following:
- Develop an aircraft-level thermal runaway test to demonstrate safety performance in the presence of an internal short circuit failure.
- Require such test as part of certification of future aircraft designs
- Reevaluate internal short circuit risk for lithium-ion batteries now in-service
- Develop guidance for thermal runaway test methods
- Include a panel of independent consultants early in the certification process for new technologies installed on aircraft
NTSB Acting Chairman Christopher A. Hart stated, “The history of commercial aviation is one in which emerging technologies have played a key role in enhancing flight safety. This is why it it’s crucial that the process by which these technologies are evaluated and certified is as robust and through as possible. These recommendations will take us further in that direction.
A final report on the Boston incident is estimated to be completed in the fall.
On January 15, 2013, a week after the initial Boston fire event, an All Nippon Airways 787 made an emergency landing after another inflight battery fire, in which passengers reported smoke in the cabin. Both Japanese carriers grounded their 787 fleets that same day, prompting the FAA to ground all U.S. registered 787s the following day. The rest of the worldwide 787 operators followed suit not long after, leading to a four month grounding.
Boeing managed to design and implement a design modification for the 787’s battery system which was to contain any such runaway. The key to these modifications was the installation of containment and venting systems for the main and auxiliary system batteries, as well as replacing the batteries and their chargers with modified components. Boeing began to retrofit 787s with the revamped systems after the FAA issued their approval on April 19. United Airlines was the first carrier to resume passenger operation a month later on May 20.