Boeing Co. will propose to regulators as early as this week a short-term fix to bolster the 787’s defenses in case of battery fires like those that have kept the jet grounded for the past month.
According to multiple sources with knowledge of the matter, the goal is to get the planes flying passengers again, while Boeing works on a comprehensive redesign of the lithium-ion battery system that could take nine months or more to implement.
The interim fix includes a heavy-duty titanium or steel containment box around the battery cells, and high-pressure evacuation tubes that, in the event of a battery fire, would vent any gases directly to the outside of the jet.
Boeing’s approach implicitly acknowledges that four weeks after two batteries overheated – one catching fire on the ground, the other smoldering in flight – investigators have still not pinpointed the cause.
That leaves Boeing with little choice for now but to engineer a solution that will do a better job of containing any such incident, and protect the airplane.
But it’s unclear if the FAA is ready yet to accept containment of an overheated battery cell rather than prevention.
“We’re not there yet,” said a government official with knowledge of the ongoing discussions, who asked for anonymity. “It wouldn’t surprise me if we’re still talking weeks before everyone is comfortable.”
Even if the FAA agrees, the short-term fix will take at least three months to design, test, certify and retrofit, said an Everett, Wash., source who knows details of Boeing’s proposed solutions.
That would mean the earliest the Dreamliners could fly passengers again would be May. If it’s much longer than that, assembly of the jets in Everett will probably have to be slowed, and Boeing’s plan to ramp up production will be severely disrupted, he said.
“This cannot drag out for six to nine months … from a financial standpoint. Think about nine months of airplanes just sitting there,” said the Everett source. “This is a gut-wrenching issue.”
Boeing will not disclose any details of the solutions it is working on.
But unlike Airbus, which said last week that it will switch to nickel cadmium main batteries for its forthcoming A350 jet to avoid the possibility of delays, Boeing insists it will stick with the high-energy lithium-ion batteries that provide emergency backup power for the 787.
“Boeing is confident in the safety and reliability of lithium-ion batteries,” said spokesman Marc Birtel, and “good progress is being made” in resolving the battery problem.
But aviation experts are increasingly worried.
Adam Pilarski of consulting firm Avitas warns that although Wall Street currently accepts Boeing’s optimism that the 787 grounding will be relatively short, this forgiving attitude may not last.
“Boeing is trying to play it down to some degree, hopeful the solution is just around the corner,” said Pilarski. “But it may take much longer. And it could have a significant financial impact.”
Ken Herbert, senior vice president with Los Angeles-based investment bank Imperial Capital, wrote in a note to investors Friday that “there are still considerable concerns as to whether the FAA will sign off on a solution that contains a potential battery fire, rather than one that prevents a fire.
“The risk to Boeing and the supply chain as a result of the 787 grounding is increasing,” Herbert wrote. “We believe the grounding costs Boeing over $25 million a month in direct costs, and the total cost to Boeing could be over $1 billion.”
That would add to the 787’s one-time development costs, which financial analysts estimate have already cost Boeing somewhere between $15 billion and $20 billion.
Additionally, before the grounding, Boeing had built up more than $21 billion in undelivered 787 inventory. For now, it continues to build the airplanes at a rate of five per month, even though it cannot deliver them.
The 50 Dreamliners delivered previously are all grounded. Boeing has 800 more on firm order.
Boeing’s proposed fixes are the result of intense, round-the-clock work by hundreds of engineers and technical experts in Everett and elsewhere.
According to Herbert, Boeing currently has approximately 90 engineers in Japan working on a complete redesign of the battery.
Boeing also appointed a top-level team from outside the 787 program, including non-Boeing battery experts, to provide clear-eyed analysis by people not wedded to previous approaches.
The initial redesign includes a fireproof battery box, made of titanium or steel, according to several sources. That would seal the cells, keeping moisture out and flames in.
It also includes a venting system that would directly evacuate to the outside any vapor and liquid flowing from the battery.
In the two recent battery-overheating incidents, flammable liquid and vapor sprayed out of the battery and across the electronics bay where the battery sits, before reaching an outflow valve.
In the longer term, the battery box will be enlarged to provide more separation between the battery’s eight cells, several sources said.
That would help ensure that overheating of one cell doesn’t spread to others – a so-called “thermal runaway” that occurred in both recent incidents.
The battery control system will have sensors to monitor the temperature and voltage of each individual cell rather than the battery as a whole, one source said.
The same source said engineers are also working on using an inert gas such as halon or nitrogen to expel the oxygen generated when a battery overheats.
Vince Battaglia, a battery scientist at the Lawrence Berkeley National Lab in California, said it is simply a matter of proper engineering to dissipate any excessive heat in a battery cell, vent any gases so it doesn’t explode, and prevent a cascade of overheating from cell to cell.
“Good engineers will know how to get the heat out of these cells,” Battaglia said. “If anyone knows how to do that, it’s Boeing.” He added that the original battery design was probably done by the Japanese manufacturer GS Yuasa, not Boeing.