Boeing has expanded the scope of its examination of 787 Dreamliners after finding more widespread instances of a manufacturing quality defect initially thought confined to the aircraft’s aft fuselage plant in South Carolina, prompting inspections at 787 component plants around the globe.
Reviews are underway at Boeing’s adjacent mid-fuselage plant in North Charleston, S.C., at the Spirit AeroSystems forward fuselage plant in Wichita, Kan., and at plants owned by Leonardo in Italy and Kawasaki in Japan that produce smaller fuselage sections.
Boeing is also inspecting every undelivered 787 on the two final assembly lines in Everett and North Charleston.
“Boeing discovered that some areas of the 787 circumferential fuselage join may not meet specified skin flatness tolerances,” said company spokesperson Jessica Kowal. “We are working with suppliers to make sure inspections happen and that rework is done as needed.”
The 787 production quality issues have slowed to a stop what was an already slow delivery rate due to the low demand for international air travel during the pandemic.
The flaw can create gaps that could potentially weaken the structure of the fuselage. While analysis shows the fuselage structure is still strong enough even with this defect to carry the maximum load the plane is expected to encounter in service, for full compliance with regulations, airliners have to meet a higher standard of 1.5 times that load.
Kowal said the defect is “not an immediate safety concern.” Federal regulators agree and so airplanes already delivered to airlines can be inspected at their next scheduled maintenance check and repaired then if necessary.
According to a person familiar with the matter, the FAA is in close discussions with Boeing about what needs to be done to fix the issues.
The FAA declined to provide details about the extent of the manufacturing problem. In a statement, the agency said it “continuously engages with Boeing” both to oversee the safety of its airplanes already in service and to review its manufacturing oversight and will “appropriately address any issues that might arise.”
787 deliveries stalled
The broadening of the problem to potentially encompass all the fuselage joins on the aircraft, first reported Monday by the Wall Street Journal, explains why 787 deliveries ground to a halt last month.
Boeing executive vice president and chief financial officer Greg Smith first disclosed at a Dec. 4 Credit Suisse conference that required inspections and rework had led to “a large number of undelivered 787 aircraft in inventory.”
“As a result, we delivered no 787s in November and expect the process will continue to slow deliveries in December,” he said.
Boeing on Monday did not provide details of what exactly has caused the defects. Kowal said Boeing is doing “a thorough engineering analysis” and that this takes time.
Still, it’s plain from the broadening of the issue to plants around the globe that this is not a question of sloppy workmanship or carelessness by individual Boeing employees.
Instead, there appears to be some issue with the automated robotic equipment used to fabricate the fuselage barrels, which are made by spinning carbon fiber tape infused with epoxy resin around a mold and then hardening it in a pressurized oven called an autoclave.
The flaws in the skin smoothness “cannot be identified by visual inspection,” Kowal said. The flatness of the fuselage skin where the join occurs has to be within 0.005 inches of the engineering specification, “no more than the thickness of a human hair,” she added.
Multiple flaws this year
The fuselage skin smoothness defect, “due to a manufacturing issue,” was originally discovered in August at the join of the two carbon composite barrels that make up the aft fuselage.
The flaw creates potential gaps between the fuselage skin and the substructure around the inside of the join that allows the sections to be bolted together.
A year earlier, Boeing had discovered a separate quality defect in manufacturing equipment — related to the small pieces of material, known as “shims,” that are precisely sized to fill such gaps — that in combination with the skin smoothness flaw produced a more serious vulnerability.
Kowal said this second flaw arose when software failed to flag that shims exceeding the maximum thickness per engineering specifications were being used.
While neither flaw on its own raised a safety of flight concern, engineers determined that the combination of the two flaws — wrong-sized shims and a non-flat inner skin surface — could together create unacceptable gaps. As a result, Boeing in August grounded eight 787s that had already entered airline passenger service and had been identified as having both flaws.
At this point, most but not all of those eight airplanes have been repaired and returned to service, according to a person with knowledge of the disposition of the airplanes.
Boeing said the earlier manufacturing flaw that produced wrong-sized shims is fixed, and so no further planes in service should need to be grounded.
In September, a separate quality defect showed up in the manufacture of the 787’s horizontal tail in Salt Lake City, necessitating a review to assess the implications for almost 900 airplanes that had already been delivered.
Kowal said the fault that caused that tail defect has been fixed in the production system.
However, the fuselage skin smoothness flaw will continue to slow 787 deliveries for some time.
Boeing delivered a total of just 53 Dreamliners through November this year. That’s down from 137 deliveries in the first 11 months of 2019.
At the Credit Suisse conference, CFO Smith said the company anticipates gradually reducing the build-up of parked undelivered 787s “through 2021.”