Boeing: Cause of Dreamliner Fires 'Almost Doesn't Matter'
"Attention ladies and gentlemen, the Boeing 787 Dreamliner will depart shortly – any potential fires caused by our lithium ion batteries will now be contained within the aircraft. Please line up at the gate for imminent boarding!”
Are you ready?
In case you missed it the Federal Aviation Administration, by publishing an Airworthiness Directive in the Federal Register last week, opened the door for the troubled “green” aircraft to return to service in the coming months. The document lays out the specifications required for Boeing to get the extremely costly project moving again, if the changes are implemented and FAA inspectors sign off.
But don’t call it a “fix,” because engineers don’t know what caused the fires in the first place. Boeing’s top engineer Michael Sinnett says the new configuration is designed to prevent a fire (the old one wasn’t??), according to the Associated Press, but even if a blaze erupts, a casing around the battery will protect passengers.
“Even if we never know the root cause,” Sinnett told reporters in Tokyo, “the enclosure keeps the airplane safe, it eliminates the possibility of fire, it keeps heat out of the airplane, it keeps smoke out of the airplane, and it ensures that no matter what happens to the battery, regardless of root cause, the airplane is safe.
“In some ways it almost doesn’t matter what the root cause was.”
Easy for Sinnett to say. As those who have followed the Dreamliner remember, the plane suffered “thermal runaway” events related to the often-suspect lithium ion batteries (also known to heat up in electric vehicles, computers, cell phones, etc.) that culminated in two major incidents with Japanese airlines in January. After that regulators worldwide removed the 787 from service so the cause(s) could be investigated.
That didn’t do much good. Not only wasn’t the source discovered, but Boeing is now broadcasting its ignorance by announcing they narrowed the number of possible causes for the fires to 80 – and that they addressed them all in the new design!
Undoubtedly as they did research and development for the 787’s batteries over 10-plus years, engineers encountered numerous potential causes of fires. Maybe it was 20, or 120, or 1020. Unfortunately, even after all that testing time, they missed “thermal event” origin Number 1021 (or whatever), and both Boeing and its airline customers have lost millions of dollars due to dormant Dreamliners ever since.
Therefore, now that Sinnett says “it almost doesn’t matter” what the cause was, will be hard to accept for potential future Dreamliner passengers. And what he said in January in an interview with the Seattle Times doesn’t make the “containment” solution soothe anxieties either.
“The electrolyte can catch on fire and that can self-sustain,” he said at the time. “Something like that is very difficult to put out. Because the electrolyte contains an oxidizer, fire suppressants just won’t work…. You have to assume it’s not going to go out. You have to assume that it’s going to go and that it’s going to expend all of its energy.”
Besides the FAA, the National Transportation Safety Board wasn’t speaking with great confidence about a quick solution in January either, as it explained that the Dreamliner’s batteries’ “spewed molten electrolytes.”
“This is an unprecedented event," said Deborah Hersman, chairwoman of the NTSB. “We do not expect to see fire events on board aircrafts. This is a very serious safety concern.”
And Hersman added, “These events should not happen as far as design of the aircraft. There are multiple systems to protect against a battery event like this. Those systems did not work as intended, we need to understand why.”
And the Air Line Pilots Association issued an opinion that said “a fire from these devices, in any situation, is unacceptable.”
So how did Boeing and its safety regulators go from “we need to understand” to “it almost doesn’t matter” in the space of three months? The near-sudden determination that the manufacturer has nailed down all (80) possible causes for lithium ion fires, and that they rearranged cells to sufficiently prevent future incidents, would seem not to be believable to the majority of the flying public. And when you take together the airplane events with an even more devastating 787 battery explosion in 2006 that caused a “devastating lab fire” in Arizona, which burned a 10,000-square-foot facility to the ground, and whose cause was never determined, why should anyone believe now the problem is solved?
Nevertheless in its new Airworthiness Directive FAA says Boeing must install enclosures and environmental control ducts for the plane’s main and auxiliary power unit (APU), and replace the main battery, APU battery, and their respective battery chargers.
“We are issuing this AD to minimize the occurrence of battery cell failures and propagation of such failures to other cells and to contain any flammable electrolytes, heat, and smoke released during a battery thermal event in order to prevent damage to critical systems and structures and the potential for fire in the electronics equipment bays.”
The directive says Boeing’s solution, which the FAA approved in March, took into account “all potential causal factors” in the two Japanese airline incidents and provides “three layers of protection” that improve battery reliability and prevent hazardous effects on a Dreamliner. Heretofore the problems with lithium ion batteries were that “thermal runaway” was a phenomenon in which a cell would overheat and catch fire, then spread to other cells (“spewing electrolytes”) until the entire blaze would burn out. As Sinnett said, most suppressants are ineffective against these types of fires.
The FAA directive is said to: contain each individual battery cell; prevent the spread from cell to cell; and protect the overall airplane should a battery fire still occur. To address the first factor Boeing plans to encapsulate each cell and use locking nuts with specific torque on each cell terminal, and will improve drainage within the battery case to remove condensation. The battery monitoring and charging unit will also be changed to reduce “electrical stress” and diminish the likelihood of overcharging.
In addition to that Boeing will add insulation between cells to “thermally and electrically isolate” the cells to prevent the spread of a problem. “High temperature sleeving” will be added to wiring harnesses to help prevent short circuits. Also venting will be improved to allow gases, electrolytes and heat to escape if an event occurs. And to protect the overall plane, Boeing will contain each battery case in a sealed stainless steel enclosure that will be connected to a duct that vents outside the plane, thus (theoretically) sending heat, pressure and gases outside the plane.
These are all probably good ideas given the technology they are working with. But if you’ve ever seen a lithium ion battery experience “thermal runaway” in a computer laptop, for example, the force and the heat can blast a pretty scary hole through metal containment. Perhaps the venting can overcome that phenomenon, but do prospective Dreamliner passengers want to take that chance?
The solution also sound very expensive, which might make you wonder whether all these measures still make the 787 economically worthwhile for both Boeing and its airline customers. Whatever the cause was, the manufacturer still needs not only to overcome the technical problem but also must repair an image that also had a huge hole blasted through it.
The airline pilots have said simple containment is not good enough. And few events incite horror among the public, especially those who fly a lot, like the image of a blazing jetliner plummeting from the sky. Seems like “it almost doesn’t matter” would not inspire confidence among the flying public, but we’ll see. All aboard!
Paul Chesser is an associate fellow for the National Legal and Policy Center and publishes CarolinaPlottHound.com, an aggregator of North Carolina news.