STEVE INSKEEP, HOST:
Federal safety investigators remain perplexed by what caused a battery on a Boeing 787 to burst into flames earlier this month in Boston. The 787, as a class of airplanes, is now grounded worldwide. And at a briefing yesterday, the head of the National Transportation Safety Board warned it could be a long time before the plane is cleared to fly. NPR's Wendy Kaufman reports.
WENDY KAUFMAN, BYLINE: Thus far, investigators from the NTSB have looked at the charred remains of the battery and the electrical system with CT scans. They've taken component pieces apart and used sophisticated technology to examine and test them. They've pored over documents, but they still don't know all that much about the sequence of events that produced a battery fire so intense that it took firefighters more than an hour and a half to extinguish it.
Still, the chairman of the safety board, Deborah Hersman left no doubt that her agency intended to find the root cause.
DEBORAH HERSMAN: We do not expect to see fire events onboard aircrafts. This is a very serious air safety concern and we are all responding to try to address what happened, why it happened and to make sure that the aircraft that fly are safe.
KAUFMAN: The battery involved was a 63-pound lithium ion battery. Lithium ion batteries are known to catch fire and the FAA imposed special conditions on Boeing's use of the battery. Extra safety measures were required. Nevertheless, there was what investigators describe as a thermal runaway inside the battery. That's an uncontrolled chemical reaction between the electrolytes and the electrodes.
Also inside the battery, investigators found evidence of high current damage from a short circuit. Aviation safety expert Hans Weber offers some possible explanations.
HANS WEBER: It could have been started within the battery due to, for example, a manufacturing defect. It could have been the circuitry that protects the battery against overcharging or excessive discharging and things of that nature. It could have been something else in the electronics control circuitry.
KAUFMAN: The NTSB will be probing other areas, too. One big one: how did the Federal Aviation Administration go about approving or certifying this new and highly innovative airplane? Here's what the Safety Board's Hersman wants to know.
HERSMAN: Were those safety certification standards adhered to and then the question of were they appropriate. We will be working very closely with a number of groups, including the FAA and Boeing as we collect that information and evaluate the analysis and the risk assessments that were done.
KAUFMAN: The NTSB says it will also be exploring safety concerns raised by more than one whistleblower. In addition, investigators are working with a team in Japan probing the cause of a severe battery failure on another 787. With no clear answers or even great clues, the Safety Board's investigation into the Boston fire will likely take some time. And once the cause is known, Boeing will have to come up with a fix and the FAA will have to test and approve it.
Aviation analyst Scott Hamilton warns that Boeing's 787s could remain grounded indefinitely.
SCOTT HAMILTON: Indefinite is indefinite. Whether that's two months, three months, six months, we don't know, but it's not going to be back in the air any time soon.
KAUFMAN: Last night, Boeing said it's continuing to work tirelessly on the problem and is assisting investigations in the U.S. and in Japan. The airplane-maker added that it deeply regrets the impact this is having on its airline customers and their passengers. What Boeing didn't say was that it deeply regrets what all this has done to its reputation and that of its flagship airplane. Wendy Kaufman, NPR News, Seattle.
NPR transcripts are created on a rush deadline by a contractor for NPR, and accuracy and availability may vary. This text may not be in its final form and may be updated or revised in the future. Please be aware that the authoritative record of NPR's programming is the audio.