Earlier this week, Boeing ordered airlines to take a batch of eight recently produced 787 Dreamliners out of service, causing them to be grounded immediately after the aircraft maker determined that a manufacturing problem was affecting an area of the carbon fiber composite structure. of the jet submerged.
So far, eight 787s – all built in recent years – have been withdrawn from flights. Aircraft for United Airlines, Singapore Airlines and Air Canada are affected by the improvised ground, according to a person familiar with the situation.
Boeing confirmed to The air stream that it has “identified two distinct manufacturing problems in the connection of certain 787 hull sections to body hulls, which, in combination, result in a condition that does not meet our design standards.”
According to those familiar with the problem, an area of the structure in the rear of the aircraft may not withstand the maximum stress that would be experienced by the aircraft in service and may fail.
“We have determined that eight aircraft in the delivered fleet are affected by both problems and therefore need to be inspected and repaired before the ongoing operation,” a Boeing spokesman said in a statement. TAC.
This new release is the first publicly known specimen in the jet’s nine-year lifespan that caused a structural defect with its most carbon-fiber aircraft that caused Boeing 787s to immediately retire from service. The 787 float was grounded in 2013 three months after the overheating of lithium-ion batteries. At that point, the 787’s worldwide framework was just 50 aircraft and the jet came back into operation after the company developed a new restraint and venting system for the main and utility programs for batteries in the electronics bay of the jet.
The source of the newly discovered structural problem is traced back to a coupling point in the rear hull between two carbon fiber composite barrels, known as Section 47/48 where the two barrels meet with a large shot that covers the pressurized cabin. The pieces were fabricated and assembled with the rear pressure shot at Boeing’s North Charleston, SC plant and then delivered for final assembly to the company’s nearby terminal building or flown to Everett, Wash.
The large white structure is the pressure shot in the Section 47 barrel of the 787 Dreamliner. The pressurized section 48 is then parked with section 48 for dispatch to final meeting.
Today, the 787 fleet is close to 1,000 aircraft and has become the backbone of international airliners in recent decades. While long-haul operations have been steadily declining since the start of the COVID-19 pandemic, the 787 fleet has seen a stronger revival worldwide in April industry operations, relative to older twin-haul aircraft such as the A330s and 777s, but worldwide 787 capacity is still 64% less than in August 2019. According to OAG, some of the two-speed fuel-efficient jetliners have been reused for all-cargo operations because travel restrictions have significantly suppressed international air travel.
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The first of the two problems that cause the release is about how naturally occurring holes in the structure become filled with shims that cause stress to be carried on the airframe when they are designed. Boeing has been using predictive mold technology on the 787 program for more than a decade, and robotic laser scans the surfaces to scan the structural joins to automatically generate the required shims to fill the holes.
In the case of the eight withdrawn aircraft, the holes were incorrectly filled. On its own, producing that may not be a direct problem, but Boeing said a second production problem required pulling the jets. The second edition deals with the inner skin of the large monolithic composite fats. On the suspect plane, the skin of the woven carcass of carbon fiber is “supposed to be enough so that there are no abrupt ridges,” said one person familiar with the problem.
The company “has conducted a thorough review of the production data regarding both shimming and skin surface profile. Based on that analysis, we were able to determine that both circumstances affected only these eight aircraft, “said the Boeing spokesman, adding that it had informed the Federal Aviation Administration” and conducted an in-depth assessment of the root cause. “
If the holes are incorrectly filled in combination with the roughness of the inner skin, the required structural strength does not meet the limit load requirements. Limit load is the maximum expected voltage that the aircraft would ever expect to experience in service. Although limit tax is not just an airline service provider, any commercial aircraft testing program must demonstrate that the structure of an aircraft is designed for limit tax before it can be safely cleared to fly for the first time.
“The rest of the in-service fleet is determined to meet limit capacity,” said the Boeing spokesman, who added that a repair is “in the ballpark of two weeks” per aircraft. The Boeing spokesman added that it “has adapted our production and verification process to ensure we build product compliant.”
Limit load is a much lower structural requirement than the much more violent ultimate cargo requirements to withstand two and a half times as much as 150% of the harshest conditions the aircraft would ever experience in flight.
In the long run, the holes left behind by improper shimming can place extra stress at certain points in the structure that can create and propagate unexpected fatigue spots. The Boeing spokesman said his engineers were “analyzing service fleet data to determine if action is needed, possibly including more frequent inspections than rework. It could also be determined that no further action is required if it is found that the condition does not affect the long life of the structure. “
The planes were taken out of service earlier this week after the company discovered the problem over the weekend. “Once we became aware of the situation, we immediately contacted the airlines operating the eight affected aircraft to notify them of the situation,” the Boeing spokesman added.
An FAA spokesman said the U.S. aviation regulator “is aware of the matter and is continuing with Boeing,” according to a statement from one sentence.
“Singapore Airlines is aware that one of our Boeing 787-10 aircraft will be affected by this technical issue,” said an airline spokesman. “The aircraft is not in service and we will work closely with Boeing on a solution.” United Airlines and Air Canada did not immediately respond to a request for comment.
Installing the shims over the 787 structure has been a recurring challenge for Boeing. Prior to the service of 787s, in June 2010, horizontal stabilizers failed due to temporary Boeing test fleet. And the problem, according to several Boeing manufacturing engineers and aircraft assemblers familiar with the situation, say structural shimming has been a challenge for South Carolina’s manufacturing industry for many years.
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“Don’t get me wrong, it’s hard to do,” said one engineer. “But they are so keen on making rate, sometimes technology and production are not apart.” In 2012, early in the 787’s production run, Boeing found more than a dozen poorly polluted longer, structural disruptors, within the same section 47/48 that required inspections and local repairs for structural delamination.
“Safety and quality are Boeing’s top priorities; we are taking the appropriate steps to resolve these issues and prevent them from happening again, ‘the spokesman said.
The recurrence of shimming problems over the Dreamliner program comes as Boeing is considering consolidating 787 definitive assembly operations exclusively to South Carolina. The North Charleston, SC factory that produces the rear hull where the structural problem was introduced, builds the part, regardless of where the last assembly was completed.
Write to Jon Ostrower at [email protected]
