Boeing told the chief US aviation safety agency investigating its faulty lithium-ion battery in its now-grounded 787 Dreamliner aircraft that it had worked closely for years with US officials on developing the battery technology.
Regulators at the Federal Aviation Administration used special new safety conditions that were proposed by Boeing as it determined the safety of the new technology, and designated company employees to have oversight of the testing on the new aircraft, according to documents and testimony.
It is not an uncommon practice; the FAA has used such designated employees for more than twenty years even though it has been criticised by regulatory experts.
Mike Sinnett, vice-president of Boeing, testified before the National Transportation Safety Board, which is conducting a two-day hearing in Washington, that it had chosen the groundbreaking lithium-ion battery because it was the best fit for the 787.
He said Boeing had never believed during the test phase of its development that the battery could cause a fire, and that even a short circuit could produce no bigger problem than a “venting of that cell and release of electrolyte”.
“The only time we were ever able to make a cell vent with fire was with significant overcharging,” Mr Sinnett said under questioning.
“We have clearly learnt a lot from the January events,” he said, adding he still believed that lithium-ion batteries were the “right choice”.
But the hearing underscored that there was something wrong with Boeing’s previous assumptions. Documents and expert testimony offered new details about the January incident that first raised questions about the battery’s safety.
On January 7 at 10:21 eastern time at Boston’s Logan airport a cleaning crew aboard a JAL jet that had arrived from Japan first discovered smoke in the cabin. Soon after, a mechanic opened the electronic equipment bay and found smoke and flames coming out of the jet’s battery.
Firefighters sought to extinguish the flames, but the battery continued to “flare up”. The mechanic felt there was a “dangerous environment” in the compartment and feared the fire might be electrical.
“After advising with mechanics they advised that it was safe to cut battery cables from battery since quick connect was melted,” according to one report.
The smouldering battery was then popped out by firefighters on the scene.
“There was no smoke or fire remaining, just black charring on the wall behind where the battery was located,” according to the report.
In another incident, an All Nippon Airways Dreamliner had to make an emergency landing in Japan after one of its batteries overheated.
Debbie Hersman, chairman of the NTSB, said there had “understandably” been much focus on returning the aircraft to flight.
“But that’s not why we’re here today,” Ms Hersman said. “Today, more than ever, with the rapid evolution of new technologies and the growing complexity of systems, it’s imperative to understand how best to oversee their development and certification.”
Boeing has said it may never know why the batteries failed.
ANA, which is the largest operator of the 787, on Monday said Boeing staff had begun modifications to the aircraft’s lithium-ion battery system.
The hearing into the faulty battery came just days after the FAA approved Boeing’s proposed fix for the battery, a move that is likely to mean the Dreamliner will resume commercial service in May or June.
Get alerts on Boeing Co when a new story is published