NTSB disputes battery safety

WASHINGTON – The government should reassess its safety approval of the Boeing 787’s lithium ion batteries, the nation’s top accident investigator said Thursday, casting doubt on whether the airliner’s troubles can be remedied quickly.

If Boeing is forced to switch to a different type of battery, it would add weight to the plane – and fuel efficiency is one of the 787’s main selling points.

The aircraft maker did get some good news Thursday: It received permission from the Federal Aviation Administration to conduct test flights under limited circumstances with special safeguards. The tests are a critical step toward resolving the plane’s troubles. The airliners have been grounded for the past three weeks. Boeing needs to test the batteries under flight conditions before a solution can be approved.

The flights will be conducted over unpopulated areas, and extensive pre-flight testing and inspections and in-flight monitoring are required, the FAA said in a statement.

But there also was new trouble for the plane Boeing has dubbed the “Dreamliner.” The National Transportation Safety Board said the results so far of an investigation into last month’s battery fire in a Japan Airlines 787 while it was parked at a Boston airport raise new questions about the safety certification of its batteries. An analysis of the origin of the fire contradicts some of the assumptions that were made about the battery’s safety at the time the system won government approval, said Deborah Hersman, the board’s chairwoman.

The NTSB investigation shows the fire started with multiple short-circuits in one of the battery’s eight cells, she said. That created an uncontrolled chemical reaction known as “thermal runaway,” which is characterized by progressively hotter temperatures. That spread the short-circuiting to the rest of the cells and caused the fire, she said.

The findings are at odds with what Boeing told the FAA when that agency was working to certify the company’s newest and most technologically advanced plane for flight, Hersman said. Boeing said its testing showed that even when trying to induce short-circuiting, the condition and any fire were contained within a single cell, preventing thermal runaway and fire from spreading, she told reporters at a news conference.

Boeing’s testing also showed the batteries were likely to cause smoke in only 1 in 10 million flight hours, she said. But the Boston fire was followed nine days later by a smoking battery in an All Nippon Airways plane that made an emergency landing in Japan. The 787 fleet has recorded less than 100,000 flight hours, Hersman noted.

The plane that caught fire in Boston was delivered to Japan Airlines less than three weeks before the fire and had recorded only 169 flight hours over 22 flights.

“There have now been two battery events resulting in smoke less than two weeks apart on two different aircraft,” Hersman said. “This investigation has demonstrated that a short circuit in a single cell can propagate to adjacent cells and result in smoke and fire. The assumptions used to certify the battery must be reconsidered.”

Investigators are still trying to determine why the first battery cell short-circuited, but the board’s findings appear to raise doubts about the thoroughness of the FAA’s safety certification of the 787’s batteries and whether Boeing can remedy the problems with the addition of a few quick safeguards. The FAA typically delegates testing of new aircraft designs to the manufacturer, while overseeing that the tests meet the agency’s requirements. The agency also relies to some degree on the expertise of the manufacturer’s engineers, especially in the case of a cutting-edge plane like the 787.

Following the fire at Boston’s Logan International Airport, Transportation Secretary Ray LaHood and FAA Administrator Michael Huerta ordered a review of the 787’s design, certification, manufacture and assembly. That review is still under way.

“We must finish this work before reaching conclusions about what changes or improvements the FAA should make going forward,” LaHood and Huerta said in a joint statement Thursday. “The leading experts in this field are working to understand what happened and how we can safely get these aircraft back into service.”

But John Goglia, a former NTSB board member and aviation safety expert, said the NTSB’s findings mean the government will likely require Boeing to re-certify the batteries.

“Certifications aren’t exactly painless and quick,” he said. “It could be a big, drawn-out thing.”

The significance of the NTSB’s findings “is if this can happen – and the safety analysis assumed that it would not happen – then the safety analysis is no longer valid,” said Jon Hansman, a Massachusetts Institute of Technology aeronautics professor and a member of the FAA’s Research and Development Advisory Committee.

Boeing issued a statement saying it is working to address questions about its testing and compliance with certifications requirements, “and we will not hesitate to make changes that lead to improved testing processes and products.”

Defending its original testing, Boeing said there were more than 5,000 hours of laboratory testing on the battery itself, including normal operations and simulated failures. Examples of these tests include baking the battery to induce overheating, crush testing, and puncturing a cell with a nail to induce a short circuit.

The battery was tested on a plane, both in flight and on ground, for more than 10,000 hours in total, the company said.