Bubbles fail to deflate Boeing’s composites plan
Failure of a large Boeing 787 composites fuselage-barrel test section is not expected to delay the new jetliner’s initial services with Japan’s All Nippon Airways in just under two years’ time. Boeing is relying on successful production of composite structures, which constitutes a significantly larger part of the new design–including the entire fuselage–than any of its previous jetliners.
To avoid delay, the U.S. manufacturer is having two replacement items made for simultaneous testing and purports not to be worried about the problem. “We’re not concerned about it. Other work we’ve done shows we know how to do this,” said program vice president and general manager Michael Bair. “We are on track for first flight on schedule [in the second quarter of 2008],” he told Aviation International News.
Inspection of the last of nine initial specimens had shown evidence of internal bubbling that compromised integrity. “It was bad enough [to show] the barrel wasn’t any good,” said Bair. “We knew it could happen. Did we wish it to happen? No.”
But the Boeing executive is confident that first 787 shipments will not be delayed. While acknowledging that the failed sample had caused “a little bit of anxiety” since it would have been used to establish certification data, Bair was at pains to say the specimen was only a test article: “That’s why you test–to find problems.”
Boeing fabricates the 33-foot-long, 20 foot-diameter samples by wrapping resin-soaked carbon fiber tape around a mandrel (or male mold) for subsequent autoclave baking. Once cooked, it removes the mandrel from the finished article.
In the case of the failed specimen, Boeing had agreed that supplier Janicki Industries should use a slightly different mandrel to take into account the 787 fuselage design changes. Also, it used a different resin mix to make the composites mandrel, one of five nonmetallic molds in use for the fuselage barrel test sections. Others, made of steel, are more durable but heavier.
A classic consideration in curing composites is avoiding bubbles in the resin, which result in voids within the finished sample. It is believed there was a leak around the mandrel in the rejected test unit which allowed gases to be trapped. Janicki Industries has resumed using the previous resin for mandrels employed for 787 production parts.
While conceding the failure, Boeing denied reports of serious problems with forward sections of the 787 and with airframe weight. However, it has confirmed that a pair of preproduction nose and cockpit sections provided by Spirit Aerosystems (formerly part of Boeing Commercial Airplanes) could not be used in production. Bair acknowledged the 787 is more than 2 percent heavier than planned, but claimed the aircraft would meet “all commitments made to customers, even if [the weight] doesn’t get any better.”
He also agreed that the program was suffering from suppliers delivering parts late. “That is the nature of the beast,” said Bair, who characterized the schedule as being deliberately aggressive. “We put the timetable in place two years ago. Things are not exactly where we hoped they would be,” he said. But he emphasized that customer deliveries would not be delayed. “Looking at the whole program, nothing says we won’t deliver the airplane when we’re supposed to.”
Boeing has not responded to reports of problems resulting from alleged incompatibility amid different suppliers’ software programs. Among changes being effected with the 787, in addition to the large increase in composites content, is the higher proportion of imported items–more than 40 major suppliers in 12 countries–and much larger use of electrical power.
Boeing may confirm plans to increase 787 production rates here at Farnborough this week. Alongside the recent announcement of a Continental Airlines order for 10 more 787s, the manufacturer said it could make an internal decision on a possible second assembly line by this month. With production sold out through 2010 and into the following year, the company has been analyzing the implications of a possible increase in production rate from seven aircraft a month to 10 beginning in 2010.
Currently, Boeing plans to deliver 112 aircraft in the first two years of production. “We are studying a production increase and could make an announcement as early as this summer,” according to marketing vice president Randy Baseler.
With Continental’s requirements doubled to 20 aircraft, 787 orders now total 360 from 26 customers, with “firm commitments” said to involve a further 33 aircraft. Operators only now signing for aircraft face deliveries not before 2012, unless existing customers release allocated line slots.
Just as Airbus was pro-active in acknowledging the failure of the A380’s wing to complete proof testing before the world otherwise found out, Boeing was able to offset reports of its own test failure by bringing forward a scheduled 787 update briefing from June to May. At that time, Bair reported “really, really good progress by all of our [787 global] partners [with] a lot of parts [already] being manufactured. Our next major milestone is the start of major assembly in Fuji, Japan, where they will start the first wing center section on June 29.”
Continuing engineering development of the 787 has seen Boeing make changes to the wing. “We’ve increased span by about six feet, or two meters, which improves aerodynamic efficiency and allows it to fly considerably further than the 787-8,” said Bair. “We’re not done tweaking,” he continued, “firm configuration of the -9 doesn’t happen for another year or so.”
Boeing is halfway through a scheduled 10-month program using an American Airlines 777 as “a concept-validation and risk-reduction vehicle,” said Bair. “The 787 has a second-generation fly-by-wire flight control system. And to make sure we have all the bugs worked out, we are also using 787 software in the 777.”
Boeing has loaded both sets of software on the 777. “With the flip of a switch, we can fly the airplane with either set,” explained Bair. “A lot of basic concepts and functionality are common, but the 787 has expanded flight-control augmentation.”
The new software accommodates requirements for gust suppression and load alleviation intended to give the airplane an improved ride quality. “And because we are actively controlling the way the airplane flies, it allows us to remove some structure and be even more fuel efficient than without fly-by-wire,” said Bair. After flight-control testing, the 777 will be used for other work, including icing testing and proving the wireless in-flight entertainment system.
After pressure from airlines for a larger 787, Boeing is working to understand the required size for the projected 787-10 but is in no hurry, said Bair. “It still looks like, in our normal tri-class seating, it’s going to be around 300 to 310 seats. We still have a lot of time to make those final decisions.”
Finally, Bair acknowledged that Boeing still faces challenges: “New programs always present surprises and while we have had remarkably few so far, we can’t count others out.”