Boeing 787 (partie 1)

Fixing a previously undisclosed 787 design flaw has now emerged as a contributor to Boeing's decision to freeze shipments from suppliers until early June.

Shear ties, which affix the fuselage frames to the skin of the aircraft, now require replacement or rework, after the initial design failed to take into account thermal fatigue loading of the parts.

The parts in question are located in the aft most part of the fuselage, inside sections 48 and 48 aft, which is the tail cone of the 787.

The problem, which was discovered in December, found that repeated cooling and warming of the unpressurized Section 48 and 48 Aft, the shear ties, those of which are made of aluminum, can pull away from the skin of the fuselage, potentially compromising the structural integrity of the aircraft.

Boeing says the solution, which will be incorporated on all deliverable aircraft, is a combination of new thicker shear ties, while an additional program source adds that radius fillers will be employed along side some existing shear ties.

The airframer says that the changes to the shear ties will not impact the current flight test or delivery schedules, and does not present an immediate safety of flight issue to the four flying 787s.

"It is a structural issue in that we are modifying the airplanes but once complete, the structure has full integrity and will meet all FAA requirements," says Boeing.

Rework on Airplane 23, say program sources, has already begun in Charleston and will be completed in Everett, as will Airplane 24. The same changes are required for Airplanes four through 22 as well, including three of the six flight test aircraft, which will eventually be delievered. A permanent design solution is planned for introduction beginning with Airplane 55.

Section 47 and 48 are both fabricated by Boeing Charleston, formerly Vought Aircraft Industries, while Section 48 Aft is made by Korean Aerospace in South Korea.

Starting with Airplane 25, shear tie modification of the Section 48 and 48 Aft will be done in Charleston and Korea, respectively.

The 24-manufacturing day hold does not represent a new production schedule as the 787 ramp up continues, rather, the pace of deliveries will quicken as the time between rate breaks is reduced.

One program source says the shear tie issue was an important driver for the 24-manufacturing day hold, while Boeing downplayed the shear tie issue as being on a long list of contributing factors.

Continued part shortages and design changes were identified by Boeing as the cause of the 24-manufacturing day hold announced on April 27 will keep structures for Airplane 23 at suppliers until early June.

While accurate, program sources say that the stoppage can be ultimately traced to the aft fuselage shear tie replacement and rework. Holding structural sections at suppliers, particularly the aft fuselage, allows for the completion of required engineering along with significantly easier access by crews to address the rework.

Once in Everett at Final Assembly & Delivery, the horizontal stabilizer is installed and access to the frames and shear ties in the aft fuselage becomes "extremely limited," they add.

Compared to a year ago, says vice president of airplane programs Pat Shanahan, design changes to the aircraft have declined by a factor of ten or greater, though he acknowledges changes, even small ones, continue to be disruptive to the manufacturing process.

During manufacturing in Charleston, Sections 47, which is the pressurized aft passenger cabin, and Section 48 which houses the aft pressure bulkhead and horizontal stabilizer, are joined, stuffed with systems, wiring, insulation and ducting before being shipped to Everett for final assembly.

Who is ultimately responsible for the design oversight remains an open question, while Boeing and Vought, which still provides engineering support to Boeing, says the other is where blame lies, says one program source.

Shear ties have been a source of supply chain disruption before. A 2007 and 2008 shortage of shear ties built by Boeing Winnipeg prevented structural frames from being installed, prompting a limited structural completion of assembly at the time of delivery.

Boeing compte accélérer la production du 787 à
10 par mois d'ici fin 2013
NEW YORK, 20 mai 2010
(AFP) Le constructeur américain Boeing compte
accélérer la production de son futur long courrier 787, dit le
Dreamliner, de 2 modèles par mois actuellement à 10 modèles par mois
d'ici la fin 2013, ont expliqué ses dirigeants lors d'une journée de
présentation aux investisseurs.
http://www.air-cosmos.com/site/afp.php?Id=100520131743.o54hbext.xml

Airbus marketing displays early 787-8 with a range of 6,990nm from Beijing with 246 passengers aboard. #AIrbusID (Boeing says 7,650nm)

If ever there was a route that the 787 was designed for, this is it.

Nearly a decade after Boeing and Airbus diverged on their respective point-to-point or hub-to-hub strategies, the first route announced for the new composite jetliner is the embodiment of the 787's business case for the new jetliner.


Continental Airlines announced on May 26 that it will launch service with its first 787 (Airplane 49) from its Houston hub to Auckland, New Zealand 7,400 (statute) miles away in November 2011. The route will be the longest from Continental's Houston hub. For the sake of technical simplicity, let's convert 7,400mi to 6,430nm.


Connecting two distant cities with just 228 seats, a relatively modest number compared to United's 374-seat 747-400 and Continental's 276-seat 777-200ER, is what the 787 was designed for. The leg between Houston and Auckland is now the third US route to New Zealand. The first two are currently operated by Air New Zealand (777/747) and Qantas (A330) from San Francisco and Los Angeles. Significant network and operating efficiencies are found in "eliminating" a leg from Houston to LAX or SFO.


Additionally, the planned link up of United and Continental is expected to bolster the new route with "the additional traffic flows through Houston that are expected to result from the merger." United nor Continental has said which colors its first 787 would arrive in at the time of first delivery next August, as the timing of merger is dependent on government approval.


While Houston-Auckland is the first 787 route is the first to be announced, it will not be the first operated. If Boeing's current delivery plan holds, the 787 will enter commercial service from Haneda Airport in Tokyo on a yet-to-be-named domestic route following first delivery of ZA100 later this year. ANA continues to keep its cards close to its vest for its early 787 routes and has not yet announced how it will configure its first. As of first flight in December 2009, ANA had not decided on either.


Airlines such as RAM, JAL, Air India, China Southern, Ethiopian and Qatar Airways will also introduce 787s in 2011.


For those watching the 787 program closely, the 6,430nm route prompted an immediate question: "Can the 787 fly that far with its added weight?"


The answer is YES.


At its recent Innovation Days briefings in the UK, Airbus, not known for its glowing technical assessment of the 787, touted the early 787's range at 6,990nm with 246 passengers aboard. At that payload, Houston to Auckland is well within the reach of Continental's first 787 with 36 business class and 192 economy seats.

Boeing says the range of the 787-8 lies between 7,650 and 8,200nm. Airplanes 7 and 20 are the earliest weight saving blockpoint changes with further enhancements planned for introduction with Airplanes 34 and 50.



While the direct great-circle route from Houston to Auckland comes in at 6,430nm, the route is operated within the bounds of ETOPS requirements across the Pacific. The ETOPS goal for 787 certification is 330-minutes, with a minimum of 207-minutes as a back up. At 207-minutes, the track across the Pacific is roughly 80nm longer than at 330-minutes as the route takes the aircraft closer to Hilo in Hawaii.


For those airplane geeks among us (you're in good company), by the end of next year, you'll be able to get from Houston to Auckland on the A380 or the 787. With a 777-200LR leg (EK212) with Emirates to Houston from Dubai, followed by an A380 flight (EK412) to Auckland with a stop in Sydney.