A current Boeing quality engineer told lawmakers on 17 April that the fuselages of more than 1,000 787s could be subject to early failure due to manufacturing “shortcuts” – an allegation Boeing firmly refutes.

The whistleblower, 17-year Boeing employee Sam Salehpour, also made allegations about quality lapses affecting 777s. Boeing likewise insists its 777 production process has been proven safe.

“I have analysed Boeing’s own data to conclude that the company has taken many shortcuts on the 787 programme that may significantly reduce the [aircraft] safety and the life cycle,” Salehpour tells lawmakers during a hearing of a US Senate investigations committee.

Boeing 787 assembly site in North Charleston, South Carolina on 15 April 2024

Source: Jon Hemmerdinger/FlightGlobal

Boeing now only assembles 787s at its site in North Charleston, South Carolina, having stopping 787 assembly in Everett, Washington in 2021

The hearing pushes Boeing back into the spotlight, again for concerning reasons. It comes one week after The New York Times reported that the Federal Aviation Administration is investigating allegations made by Salehpour, who is an engineer but not a fuselage-stress specialist.

At issue are small, out-of-specification gaps between 787 fuselage sections, and the means by which Boeing brings those sections together during manufacturing.

Boeing’s own company-set specifications call for the gaps not to exceed five thousands of an inch, or 0.12mm. But in 2020, it began finding that some gaps are larger than allowed.

Salehpour says he reviewed internal Boeing data related to 28 787s and found that 98.7% of gaps that were to be filled with shims were not.

“This omission, which I believe has affected more than 1,000 787 airplanes in service, is likely to cause premature fatigue failure over time in two major airplane joints,” he says in written testimony.

But Boeing engineers insist a wealth of data demonstrates that the 787’s carbon-fibre fuselage is incredibly safe – even with out-of-specification gaps. The gaps, while not conforming to the design, pose no safety concern, and tests indicate that the fuselages can retain necessary strength for far more flights than any jet will ever operate, they say.

“There is nothing in these composite joins – in anything we’ve seen, in any testing we’ve done, including the full-scale testing – that is demonstrating there is any concern with the fatigue or durability of this structure,” Boeing functional chief engineer of mechanical and structural engineering Steve Chisholm said on 15 April at Boeing’s 787 assembly site in North Charleston, South Carolina.

“I am not concerned about the durability or the fatigue performance of [the] composite structure,” he adds.

Boeing vice-president of airplane programmes engineering Lisa Fahl

Source: Laura Bilson/The Post and Courier

Boeing vice-president of airplane programmes engineering Lisa Fahl points on 15 April 2024 to a fuselage joint where Boeing identified out-of-specification gaps

The company said on 15 April that it now knows the gap issue has existed since the start of production, meaning many – perhaps all – 787s may have out-of-specification gaps. “That aircraft is highly capable of much larger gap allowances,” says Boeing vice-president of airplane programmes engineering Lisa Fahl.

The company says specialists completed “intensive structural maintenance evaluations” on 10 787s, and found no issues. It says 671 787s have undergone six-year maintenance inspections, and eight been through 12-year inspections, without findings.

While Boeing has inspected gaps on new 787s prior to delivery (it is filling gaps with shims if necessary), most aircraft already flying have not undergone gap inspections. Boeing says in-service jets are perfectly safe, though its analysis about the problem, and about whether actions for in-service jets will be needed, continues.

Salehpour also alleges that in assembling 787 fuselages Boeing has used excessive “fit-up force” – the force used to bring components together prior to fastening – and that Boeing’s methods can allow drill shavings, or burrs, to become trapped in gaps between fuselage components, decreasing fuselage integrity over time.

Boeing has indeed started using stronger fit-up forces – now up to 150lb (68kg) – but those changes “were approved per our engineering and supported by analyses”, says Fahl.

The company also insists it has no concern about burrs or other debris trapped between structures. For the 787, Boeing uses a rather unique assembly process that involves drilling between structures and then securing them with fasteners – without first separating the structures between drilling and fastening. With traditional aircraft manufacturing, workers separate the structures to remove burrs and other debris prior to fastening.

Boeing insists its process has been fully validated.

“We proved through qualified processes that you clamp it appropriately so that you don’t leave debris in the interfaces between the fasteners,” says Fahl. “A significant amount of testing is done to support that assembly process.”

Even so, unlike with metallic structures, small debris trapped between composite materials “does not have an impact on the durability because the [debris]… can embed in the surface layers of the composite”, adds Boeing functional chief engineer of mechanical and structural engineering Steve Chisholm.

The whistleblower also told lawmakers that Boeing “prioritises speed of production over safety”, and claims that employees who raise safety concerns can be “ignored, marginalised, threatened, sidelined and worse”.

Boeing insists it has taken many steps to encourage employees to speak up about safety.

Salehpour alleges similar concerns with how Boeing produces 777s. Originally, the company assembled that widebody type using a “floor-mounted assembly tooling” process that began with fuselage sections being assembled while upside down.

But in 2015, after 10 years of evaluation and testing, Boeing converted the 777 programme to an “upright build” assembly. Upright assembly allows for tighter tolerances, less variance between jets and faster assembly, executives say.

Boeing's North Charleston 787 assembly facility

Source: Laura Bilson/The Post and Courier

Boeing produces 787 aft-fuselage sections from carbon fibre in North Charleston

But Salehpour says Boeing failed to adequately redesign parts to work with the new system, “resulting in significant misalignment between parts in the assembly of hundreds of 777 airplanes”.

Boeing pushes back, saying: “We are fully confident in the safety of the 777, which remains the most-successful widebody airplane family in aviation history”.

The company says 27 777s assembled using the upright method have been inspected, as have 114 777 Freighters with aft-fuselages assembled using the new process, with “no fleet findings”.

Also on 17 April, a separate Senate committee heard testimony from members of an panel formed by the FAA that recently released a report critical of Boeing’s safety culture.

“There exists a disconnect between the words that are being said by Boeing management and what is being seen and experienced by the technicians and engineers,” Javier de Luis, an aerospace engineer and member of the panel, tells the Senate Commerce Committee on 17 April. Employees hear ‘safety is our number one priority’, but they see that that is only true as long as you meet your production milestones.”

de Luis’s sister died on Ethiopian Airlines flight 302, a 737 Max 8 that crashed in 2019, killing all 157 people aboard.