The National Transportation Safety Board (NTSB) has directed several recommendations to the Federal Aviation Administration (FAA), derived from the agency’s ongoing investigation of the January fire that occurred in a Boeing 787 lithium-ion battery.
Investigators found that the battery involved in the Boston fire event showed evidence not just of 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.”
The 12-page letter said that safety tests performed in 2006 were inadequate, because there is no standardized thermal runaway test that’s conducted in a real-world environment. Because there is no such test, the NTSB said that battery designs on airplanes currently in service might not have adequately accounted for the hazards associated with internal short circuiting.
The NTSB specifically asked the FAA to:
- Develop an aircraft-level thermal runaway test to demonstrate safety performance in the presence of an internal short circuit failure.
- Require this test as part of certification of future aircraft designs.
- Re-evaluate internal short circuit risk for lithium-ion batteries now in service.
- Develop guidance for thermal runaway test methods.
- Include a panel of independent expert consultants early in the certification process for new technologies installed on aircraft.
“The history of commercial aviation is one in which emerging technologies have played a key role in enhancing flight safety,” said NTSB Acting Chairman Christopher A. Hart. “This is why it’s crucial that the process by which these technologies are evaluated and certified is as robust and thorough as possible. These recommendations will take us further in that direction.”
The NTSB is expected to issue its final report on the fire investigation in the fall.
All of the information the NTSB has released for this investigation so far can be accessed from: http://go.usa.gov/4K4J.