In a my previous post concerning the incident in which a Southwest Airlines Boeing 737-300 lost a portion of fuselage skin, I concluded that the problem was not caused by a flaw in design, materials, or construction of the airplane. I still believe that to be the case, but an additional issue deserves attention.
The hole in the upper fuselage developed when undetected cracks compromised the structural integrity of a “lap joint” where one section of aluminum skin overlaps another and both are fastened to a “stringer” with glue and rivets. This is a common method used by all aircraft manufacturers, and there’s no indication that the joint had not been properly constructed at the factory.
No one likes to think that aircraft design engineers guess at anything, even if the prediction is a well-educated one, but that’s the reality when it comes to determining the rate at which metal fatigue will affect the integrity of an aircraft structure. Boeing engineers postulated that the fuselage lap joints in the 737-300 would remain problem-free for up to 60,000 pressurization/depressurization cycles. In practical terms, this means that inspection of these joints would not be necessary until many years after manufacture.
The fact that the incident aircraft had logged only 39,871 cycles, and three other 737-300s in the Southwest fleet showed evidence of cracks along lap joints, obviously directs the spotlight on procedures used to develop the fatigue prediction. Fortunately, the incident resulted in no major injuries and we can be thankful that the potential for similar incidents in the future will be reduced, if not eliminated, by an abundance of caution in adopting changes to inspection criteria.
The purpose of this post is to highlight the potential for surprises when aircraft design engineers blaze new trails in the aviation wilderness, and the example used to illustrate the issue is that of the Boeing 787 Dreamliner, the newest in a long list of stalwart Boeing aircraft in the 700 series.
The Dreamliner is a long-range, mid-size, wide-body, twin-engine jet airliner. It seats 210 to 330 passengers, depending on the variant. Boeing states that it is the company’s most fuel-efficient aircraft to date and the world’s first major airliner to use composite materials for most of its construction. The 787 consumes 20% less fuel than the similarly-sized Boeing 767. Some of its distinguishing features include a four-panel windshield, noise-reducing chevrons on its engine nacelles and a smoother nose contour.
With primary construction in progress at the Boeing factory in Everett, Washington, the process might as well be on the Moon in terms of visibility to any but industry watchdogs. Dominic Gates, Seattle Times aerospace reporter, is one such bloodhound as indicated by his assessment published December 8, 2010, titled “Dreamliner’s Woes Pile Up.”
And as a friend of mine put it, “Outsourcing is a major factor of this whole expensive scary mess. Again, Rule #1 – Never fly or drive the ‘A’ model of anything.”
With only minor editing, Gates’ article follows:
As Boeing prepares to announce yet another delay for the 787 Dreamliner, at least three months, possibly six or more, the crucial jet program is in even worse shape than it appears. The problems go well beyond the latest setback, an in-flight electrical fire last month that has grounded the test planes.
A year after the airplane’s first flight, the cascade of systems failures caused by that fire, as well as two major problems since summer with the 787′s Rolls-Royce engine, have raised red flags with aviation regulators. A top Federal Aviation Administration (FAA) official 10 days ago warned Boeing that without further proof of the plane’s reliability, it won’t be certified to fly the long intercontinental routes that airlines expect it to serve.
Meanwhile, on the production side, one veteran employee on the 787 said he’s witnessing “the perfect storm of manufacturing hell.” The global supply chain is at a standstill, and outside the Everett factory the rows of partly finished jets will take many months to complete. To deliver the 20 Dreamliners built since the six flight-test planes, mechanics will have to complete more than 100,000 tasks.
Among the 787′s lesser ongoing problems is “rain in the plane,” the term used for heavy condensation dripping inside the jet’s composite plastic fuselage. Yet that issue is piddling compared with the major flaws that have brought a wave of successive delays.
“The purpose of flight tests is to find out what you did wrong,” said a senior engineer who expects the 787 will ultimately prove successful. “But the amount of stuff we are finding is horrible. We shouldn’t be dealing with this many issues this late in the program.”
With the Dreamliner nearly three years overdue and a postponement of the mid-February target for first delivery expected to be announced by Christmas, analysts estimate Boeing’s cost overruns at a staggering $12 billion or more. The head of the 787 program, Scott Fancher, conceded in an interview this past week that he and his team have “a tough job in front of us. There’s no doubt we’ve had a lot of challenges. The development of a new airplane is hard, especially one with as much innovation as this.”
More than a dozen people who work on the Dreamliner or have some knowledge of the program’s state were interviewed for this story. All were granted anonymity because Boeing doesn’t permit employees to speak publicly about its internal problems. Boeing has bet its future on the 787, which made its maiden flight one year ago. The company aimed to reduce the cost and risk by outsourcing an unprecedented share of manufacturing and design work to partners around the globe. It’s the first new Boeing jet in more than 15 years, and the first airliner built largely from light, tough carbon-fiber-reinforced composite plastic.
And it’s been a marketing blockbuster: Despite a total of 120 cancellations, Boeing still has 846 orders. Yet the 787 has run into more trouble than any previous Boeing jet. The company’s original internal target for its own development costs was $5 billion. But with yet another delay, several Wall Street analysts estimate that fixing the litany of manufacturing problems, plus paying penalties to suppliers and airlines, has piled on an additional $12 billion to $18 billion.
The 20 built but incomplete Dreamliners sitting in Everett are emblematic of all that has gone wrong. They are so far from done that the total number of unfinished jobs exceeds 105,000. Counting further rework planned after some of the jets are flown to San Antonio, Texas, for refurbishment before delivery, the tally of incomplete jobs is more than 140,000.
“Some jobs take a day, some take weeks,” said a worker dealing with the backlog. Boeing is reworking six partly finished jets at a time, two of them in an empty bay inside the factory, two in a hangar at the south end of Paine Field, and two more on the flight line. Mechanics can complete only about 500 jobs a month out on the field, and perhaps 1,000 jobs a month on those inside the factory, the person said.
These jets have no seats or sidewalls, and many interior systems are missing or incomplete. Passenger doors are missing. Mechanics installed temporary air-conditioning units after those fitted initially kept failing. Horizontal tails poorly built by Alenia in Italy are still being reworked. With the workmanship on the tails varying from one plane to the next, mechanics have to painstakingly customize the fixes plane by plane. (That headache at least produced one piece of good 787 news for this region. Alenia will still build 787 tails, but as Boeing ramps up beyond seven planes a month, it plans to build the additional tails in the Puget Sound area, possibly at its parts-manufacturing plant in Auburn, according to employees.)
Despite the attention focused on achieving the first delivery, the manufacturing quagmire suggests that Boeing will be slow to deliver the next few dozen planes.
With its parked Dreamliners many months from completion, Fancher said Boeing is likely to skip over earlier planes that need more work and move up the delivery of some later-built, more completed jets. “You may see us hopping around a bit,” he said, adding that it’s a matter of balancing the most efficient way to finish the work with the customers’ need to get a specific jet by a specific date. The worker dealing with the backlog puts it differently: “They’ve dug a hole so deep, they have no choice but to go around it and leave the hole there.”
On Boeing’s 747, 767 and 737NG programs, parts shortages and late redesigns on early planes also stacked up dozens of incomplete jets on the flight line. But the company worked through those stacks without skipping over a significant number of deliveries.
Meanwhile, the flight tests have brought new design problems to light. After runway tests in Roswell, N.M., in September, four Rolls-Royce engines had to be swapped out from the flight-test airplanes. According to a person familiar with the problem, mechanics discovered cracking of small blades called airfoils in one of the engine’s compressors. GE and Rolls both provide 787 engines, but the Rolls engine will power most of the early Dreamliners.
A separate and more serious incident occurred a month earlier, when a Rolls engine blew up on a ground test stand in England, sending metal pieces shooting out of the engine casing. Another person with knowledge of that event said an investigation afterward revealed that one of the engine shafts can, under certain conditions, turn too fast. That may not have caused the blowup, but it is out of compliance with FAA regulations.
Rolls is testing hardware and software changes to solve the problem, though it hasn’t won approval from the regulatory agencies. Company spokesman Josh Rosenstock said Rolls is convinced the engine will pass muster with the FAA in time for Boeing’s delivery schedule. However, the engine modifications, plus an electrical system redesign needed as a result of the in-flight fire last month, will add to the glut of out-of-sequence work in the jets already built.
Earlier this month, John Hickey, the FAA’s deputy associate administrator for aviation safety, visited Seattle and warned 787 executives that in the current state of the program, the jet cannot be certified for long-distance transocean and transpolar flights, according to a person familiar with the details.
Boeing designed and marketed the 787 as an ultra-long-range jet, and its customers are counting on that capability from the moment the plane enters service. But the 787 wouldn’t be allowed to fly more than 60 minutes from the nearest airport without the certification known as ETOPS, for Extended-range Twin-engine Operational Performance Standards. That would drastically curtail the use of the jet for many airlines, including launch customer All Nippon Airways of Japan.
Hickey, a former Boeing engineer, put Boeing on notice that to get an early ETOPS rating the company will have to do more to demonstrate the plane’s reliability, including specifically the reliability of the engine and electrical systems. Dreamliner chief Fancher confirmed the recent meeting with the FAA over ETOPS and acknowledged that engine and electrical system reliability were discussed. But he said that such meetings about the FAA’s certification requirements are “typical,” and that Boeing will “fully address their concerns.”
Also drawing separate FAA scrutiny is repeated poor-quality workmanship in the 787 fuel tank, including issues with fasteners, said the person familiar with the FAA visit. That problem reaches back into the 787 supply pipeline, which continues to stutter.
Suppliers go slow
In November, for the fourth time this year, Boeing stopped moving planes forward on its final assembly line and halted deliveries of the major sections to Everett. Just one airplane had come off the line since the previous line stoppage in October. Fancher said the line halts are part of his “balancing act” to allow some suppliers to catch up with others and to slow the flow onto Paine Field of new planes needing to have the latest fixes applied. Despite the slowdown, he said, the supply chain is improving.
Fancher cited “solid progress” at Boeing Charleston, which makes the 787′s rear end. He conceded that Alenia of Italy “definitely remains a challenge.” The other partners and the final-assembly team in Everett are “coming down the learning curve nicely,” he said. For now, though, the pipeline is still blocked.
Spirit AeroSystems of Wichita, Kan., which makes the Dreamliner’s forward section, has reassigned most of its 787 work force until work picks up again. And though in recent years Boeing’s 787 employees have worked through most of the Christmas holidays to catch up, a worker at Boeing Charleston said that plant this year will largely shut down its production lines. The latest delay will at least give engineers more time to test design fixes, including some for less consequential troubles, not uncommon on new jets, such as the maddening drip, drip, drip of “rain in the plane.”
On 787 flight tests, drip trays padded with squares of absorbent cloth are positioned to collect the condensation. Fancher said “a good design fix” to dehumidify the interior is being installed and will be tested when the Dreamliners resume flying. Employees working on the 787 complain about insufficient oversight of suppliers and a management system that the senior engineer called “totally broken.”
“This program is not like anything we’ve seen,” said the veteran 787 employee. “It’s a screwed-up mess.” Yet Fancher said the feedback he receives is that employees are “proud to be part of an adventure like this.” He insists his team will surmount all the problems.
“This is a great airplane. It will deliver on the promises,” Fancher said. ” Our job is to get it over the goal line.”