By Dominic Gates / The Seattle Times
Last spring, Federal Aviation Administration managers approved removing a key feature of the 787 Dreamliner wing that aimed to protect it in the event of a lightning strike.
Boeing’s design change, which reduces costs for the company and its airline customers, sped through despite objections raised by the agency’s own technical experts, who saw an increased risk of an explosion in the fuel tank inside the wing.
FAA scrutiny of Boeing has been an intense focus since two crashes and the grounding of the Renton-built 737 Max model. But until now comparatively little has emerged about how well the agency is overseeing Boeing’s other airplane models, all built in Everett, including the 787, which is also assembled in North Charleston, South Carolina.
Lightning protection on an airplane like the 787, which is fabricated largely from carbon composites, is more elaborate than on a metal aircraft. When Boeing developed the Dreamliner, it included special measures to protect the wing fuel tank. It sealed each metal fastener in the wing with an insulating cap and embedded copper foil in strips across the carbon wing skin to disperse the current from any lightning strike.
Five years ago, Boeing quietly stopped adding the insulating fastener caps. Its own engineers approved the change with minimal input from the FAA.
Then, in March, it stopped adding the copper foil. The entire wing surface of any 787 delivered since then now lacks both protections.
The FAA initially rejected the removal of the foil from the wing on Feb. 22, when its certification office ruled that Boeing had not shown, as regulations required, that the ignition of fuel tank vapor by a lightning strike would be “extremely improbable,” defined in this case as likely to occur no more than three times in a billion flight hours.
By then Boeing had already built about 40 sets of wings without the foil.
Facing the prospect of not being able to deliver those airplanes, Boeing immediately appealed. FAA managers reversed the ruling exactly a week later.
In June, a senior FAA safety engineer, Thomas Thorson, formally objected, concerned that the agency was hurriedly approving Boeing’s desired changes so it could deliver planes it had already built.
“I do not agree that delivery schedules should influence our safety decisions and areas of safety critical findings, nor is this consistent with our safety principles,” Thorson wrote.
FAA management has faced heavy criticism for the way it took scrutiny of the now-grounded 737 Max’s certification away from its own technical staff and delegated most of the approval process to Boeing itself.
The 787 decision, which came as Boeing was pushing to reduce the cost and complexity of manufacturing the jet, raises similar concern.
Boeing says the changes were introduced as its understanding of lightning protection evolved, both in terms of what works well in practice and in what’s needed to meet the FAA requirements.
In a statement, Boeing said the 787 has “several other layers of protection from lightning strikes” and that each design change “was properly considered and addressed by Boeing, thoroughly reviewed with and approved by the FAA.”
Thorson, propulsion technical project manager at the FAA, wrote that the agency’s technical experts discovered errors in the way Boeing summed up the various risks of the lightning protection features and that with the removal of the foil “the fuel tank ignition threat … cannot be shown extremely improbable.”
Thorson estimated that if the math were corrected, the ignition risk “would be classified as potentially unsafe.”
He recommended that the FAA reject Boeing’s assertion that it complied with regulations “due to the amount of risk that the FAA would be accepting for fuel tank ignition due to lightning.”
Thorson also objected to the FAA delegating to Boeing itself a system safety assessment of the design change that was specific to the largest Dreamliner model, the South Carolina-built 787-10, because of different details inside the wing.
He wrote that the rationale provided for this delegation of oversight was the FAA’s inability “to support the airplane delivery schedule.” The FAA’s approval of the design change for that specific model on June 28 allowed Boeing to go ahead the next day and deliver a 787-10 to Dutch airline KLM.
The 787 lightning protection changes were first raised last month in a letter to the FAA from Rep. Peter DeFazio, D-Oregon, chair of the House Committee on Transportation and Infrastructure, and Rep Rick Larsen, D-Everett, chair of the Aviation subcommittee. The committee provided Thorson’s letter and other supporting documents after a request by The Seattle Times.
FAA Administrator Steve Dickson wrote to the committee on Friday insisting that “the design change had no unsafe features” and that the 787s produced since the removal of the copper foil from the wing skin are “currently safe to operate.”
Still, in October, perhaps in response to the mounting criticism of its oversight role, the FAA seemed to take a step back.
In a letter to Boeing, the agency’s airplane certification unit said the “cumulative effect of multiple issues” affecting the 787’s lightning protection — including the deliberate design changes, a sequence of Boeing manufacturing errors and the discovery that some lightning protection features proved inadequate in practice — raised concerns that the risk from a lightning strike is greater than the regulations allow.
As a result, eight years after the FAA gave its original approval to the 787, and months after approving the removal of the foil from the wing, it asked Boeing to conduct a formal re-assessment of the risk of a fuel tank explosion in the 787 wing.
Boeing is currently conducting the new risk assessment ordered by the FAA in October.
In addition to the removal of insulating caps from metal fasteners and copper foil from the carbon wing skin, the FAA has asked Boeing to consider multiple other changes it’s made to details inside the fuel tank.
Most of the design changes reduce complexity, cost and weight. Boeing has steadily reduced the cost of building the 787, a vital part of its drive to recoup the $22 billion in still-outstanding 787 production costs deferred into the future.
The FAA said it also wants Boeing to assess the risk from discoveries since the plane entered service.
Appearing before DeFazio’s committee Wednesday, FAA chief Dickson was pressed to defend his agency’s independence from industry and the integrity of its oversight.
His written response to the committee insisted that Boeing’s decision to delete copper foil from the 787 wing skin complied with all FAA requirements and that the reassessment now underway of the jet’s lightning protection was not driven by that change.
And he denied there’s any “concern that a short-term or urgent safety issue exists.”
The FAA engineer who spoke to The Seattle Times said he found these were conflicting assertions. On the one hand, the FAA says the 787 is safe. On the other, it’s ordered Boeing to recheck that it’s safe.