Clues to how the battery packs on two Boeing Co. 787 planes failed are proving difficult to unearth, leaving uncertain when regulators will clear the model to fly again.
Boeing said yesterday it won’t deliver more 787s until the U.S. Federal Aviation Administration instructs it on how to prove the Dreamliner’s flammable lithium-ion batteries are safe. Halting handovers of Boeing’s most advanced model adds to fallout from the Jan. 16 FAA grounding order, which was followed by regulators worldwide, affecting about 50 planes.
Authorities won’t lift the order until they are “1,000 percent sure” the planes are safe, U.S. Transportation Secretary Ray LaHood, whose agency oversees the FAA, said in Washington yesterday.
“These things take time,” LaHood when asked about the grounding by reporters at a U.S. mayors’ conference. “We just have to be patient here.”
LaHood pronounced the 787 safe in a press conference Jan. 11 announcing a review of its safety by the FAA. He said he had no reservations flying on one.
That changed after the latest battery-related incident this week, he said. “Last week it was safe,” he said.
The FAA and its counterparts abroad acted after an emergency landing by an All Nippon Airways Co. plane on a domestic flight in Japan on Jan. 15 because of a battery-fault warning. They were already investigating a battery fire on a Japan Airlines Co. 787 on Jan. 7 in Boston that took 40 minutes to put out.
Lithium-ion batteries can burn at high temperatures and spew molten metal like a roman candle, according to testing performed by the FAA. Because these batteries contain their own oxygen source, fires can be challenging to extinguish.
“That is very, very difficult,” Dan Doughty, retired manager of battery research and development at Sandia National Laboratories in Albuquerque, New Mexico, said of the forensic investigation of battery fires. “The evidence gets destroyed.”
Investigators are looking into whether the battery packs in both cases could have come from the same batch, which could signal a common flaw caused the failures, according to two people familiar with the incidents. The people weren’t authorized to speak publicly.
Such a pattern, if confirmed, may show the flaws were confined to a small number of 787s, rather than a systemic fault with the plane’s engineering, design or manufacturing.
The FAA and Boeing, working alongside accident investigation agencies in the U.S. and Japan, are trying to determine what prompted charring and the release of fumes from the battery packs, said a person familiar with the deliberations who wasn’t authorized to speak about them.
Boeing has tried to persuade the FAA to end the groundings by proposing a variety of inspections and having pilots monitor electronic signals from the batteries prevent fires, the person said. The FAA has been reluctant to approve those steps without a clear idea of what caused the defects and how they can be prevented, the person said.
The FAA gave Boeing permission to use lithium batteries, under a so-called special condition now being reviewed, in 2007, three years after it banned the shipment of non-rechargeable lithium batteries on passenger planes because of the fire danger.
The 787 uses five times as much electricity as the 767, enough to power 400 homes. To jump-start a so-called auxiliary power unit that’s used on the ground and as a backup in case all the plane’s generators failed, Boeing decided on a lithium-ion battery because it holds more energy and can be quickly recharged, Mike Sinnett, the 787 project engineer, said in a briefing last week.
In a worst-case scenario in which the batteries burn, they are designed to do so in a way that doesn’t threaten the aircraft, Sinnett said. If the jet is airborne, smoke is supposed to be vented out of the compartment so it doesn’t reach the cabin, he said, and the plane’s ability to stay aloft wouldn’t be harmed even if all of the battery cells ignite.
Doughty, who worked at Sandia for 27 years and now is president of Battery Safety Consulting Inc. in Albuquerque, said the intensity of lithium-battery fires can often destroy the evidence of what triggered them.
If a battery cell catches fire due to a circuitry error that allows it to be overcharged, for example, the heat may damage or destroy the electronic equipment that caused the failure, he said.
One factor that may help authorities is the advanced electronics of the 787, Doughty said.
The plane has computer networks aboard and stores vast amounts of data about how its systems operate, according to FAA documents. Like other commercial aircraft, it has a data recorder that monitors each flight. The so-called “black box” recorders from the Japan Airlines 787 in Boston were taken to the U.S. National Transportation Safety Board’s lab in Washington, the agency said in a release.
“That, in principle, should be a big help,” he said.
A U.S. probe into a lithium-ion battery fire on a General Motors Co. Chevrolet Volt, a plug-in hybrid car, took seven months to complete.
After a crash test of the Volt conducted by the U.S. National Highway Traffic Safety Administration, coolant leaked into a damaged battery-pack circuit board, causing a fire, the report released in January 2012 found. GM in response strengthened protections for the battery packs.