Paris 2011: Boeing’s 747-8 On Track for Summer Certification

Paris Air Show » 2011
Now having accumulated some 300 hours of flight testing, the 747-8I has trave...
June 19, 2011, 9:40 PM

The so-called “pause” or “rebalance” of the Boeing 747-8 production line officially ended on June 7 as the company prepared to bring both new versions of its venerable jumbo jet–the Freighter and the Intercontinental–to Paris for this year’s salon. The main reason for the issues was a large backlog of out-of-sequence work had accumulated due to certain flight-test discoveries and engineering changes associated with the Intercontinental.

Although it never stopped work on the line, Boeing instituted the “rebalancing” to prepare for an eventual rate increase from one-and-a-half airplanes to two per month, starting this September or October with “on the job training.” According to Elizabeth Lund, 747-8 vice president and general manager, the actual rate break will happen in December at the beginning of the production line in the wing spar shop, and the first delivery at the new rate will kick in next May.

 “We called it a rebalance–a pause–and there’s reason we called it a rebalance,” said Lund. “I think some people have asked, ‘Is it a shutdown?’ A shutdown has a connotation that we’ve had to shut down the line because we don’t have enough parts and things, and that’s absolutely not where we’re at right now.

 “This is an established supply chain; it’s really the traditional 747 supply chain, and the supply chain is healthy. And we’ve just taken this chance to really work through all of our engineering issues, get them all back in sequence, get in position so we can go into rate break healthy…We wanted to do it now because engineering’s complete; it is a good time and it really sets us up to increase rate.”

Although Boeing said it did not expect the measure to affect the schedule for first delivery of the 747-8F Freighter to Cargolux when it announced the pause in line movement in early May, Lund told reporters during an early June briefing in Everett, Washington, that first delivery would happen some time this summer.

Whether the Freighter wins its certification by mid-year, meaning some time early this summer, or closer to the fall, it will reach the market some two years later than originally planned. Still, given the “challenges” the program has faced since its launch in late 2005, that it could conceivably gain certification before the 787 earns its ticket speaks volumes about the progress Lund and her team have recently witnessed.

As of early this month the program had produced twenty 747-8s, five of which participated in Freighter flight testing and two of which have flown tests for the certification of the Intercontinental (the 787-8 passenger version), due by the end of the year. By June 2 Boeing had finished some 87 percent of the test items needed for certification, said Lund, and the first test airplane had finished all its flight test duties. With four airplanes remaining in the Freighter flight-test program, Boeing has “retired” all of its high-risk testing, she added.

Earlier this month, Freighter airplane number-one needed to accomplish about a week-and-a-half of stability and control testing; airplane number-two was finishing propulsion certification testing; airplane number-three performed what Lund called some miscellaneous testing and the Freighter program’s last airplane, airplane number-five, began flying functionality and reliability testing on June 1.        

Meanwhile, the two flight-test articles used to test the 747-8 Intercontinental had already finished some 25 percent of their required flying since the first example took to the air in March and the second in April.

The first airplane has completed the first phase of the stability and control program, during which Boeing gains an understanding of its handling and performance characteristics and runs through “tuning cycles” for software programs related to items such as autoland and autoflight. The second Intercontinental, a Lufthansa aircraft equipped with a full interior, has begun testing changes made to the environmental control system (ECS) to accommodate the new, larger interior, said Lund.

“We also just finished our NAMS [nautical air mileage survey] testing for the Intercontinental,” she said. “And we are understanding exactly what the fuel performance and fuel burn will be on the aircraft…it will take us a month or two to take all the data and burn it down. But we’re on track, on schedule…and the airplanes are really flying well, so we’re very pleased with how that’s going.”

An earlier problem involved buffeting at flaps setting 30 on the Freighter. This forced an adjustment to the detents to make them identical to those on the Intercontinental.

Another problem centered on a 2.3-hertz vibration at the tip of the wing. Although Lund said the one-inch of movement didn’t amount to a safety issue, test pilots could feel it and it didn’t dampen itself on its own, technically signaling flutter. Boeing solved that problem with an outboard aileron modal suppression system dampens pitch, counteracting the oscillation in the wing tips and effectively removing the vibration.

“So the big [problems] that you’ve been hearing us talk about that delayed the program are behind us,” said Lund, who added that Boeing has applied all the fixes to the Intercontinental as well.

Featuring new General Electric GENx-2B engines, a redesigned wing, new alloys in the fuselage and a new interior in the Intercontinental that can hold 51 more passengers and 26 percent more cargo in the lower lobe than the 747-400 can carry, the 747-8 also uses a completely new flight management computer that Lund admitted “absolutely” presented “challenges.

“What’s made this a difficult development program is just the complexity of the FMC [flight management computer] and the brand-new architecture,” said Lund. Although Honeywell’s FMC will not immediately deliver all the functionality its designers had initially planned, it will do everything the computer on the 747-400 can do, and more, she insisted. In fact, by the time the Intercontinental enters service, Boeing expects the FMC to prove itself even more capable after some further software development.

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