Posted on 08/13/2009 7:10:29 PM PDT by Yo-Yo
Alenia Aeronautica has halted production of two major 787 structural components due to wrinkles in the fuselage skin caused by manufacturing flaws in subcomponents of the one-piece composite barrel, according to a letter obtained by FlightBlogger.
The letter's subject: "SECTION 44 and 46 STOP WORK ORDER FOR BARREL" details a correspondence between Jay Campbell, sr. manager for supplier management for the 787 fuselage supply chain, James E. Simmons section 44/46 sr. engineering manager and Ciro Occipinti of Alenia Aeronautica in Naples, Italy.
The letter, signed and dated June 23 on Boeing letterhead, was sent the same day Boeing announced the latest delay in the program citing a need to reinforce the side of body structure.
Boeing and Alenia Aeronautica did not respond to multiple requests for comment. The status of production at Alenia's Grottaglie facility remains unknown at this hour.
This structural issue, sources say, appears entirely separate from the wing fix. Section 44 and 46 are two of the four major structural components that comprise the integrated center fuselage. Section 44, a bonnet section, sits directly on top of the center wing box (section 45/11) while section 46, a complete barrel, is joined to the aft part of the center wing box.
Campbell and Simmons explain the justification behind the production halt as "related to stringer edge steps" causing wrinkles in the skin of the fuselage that were larger than previously "demonstrated during the [preproduction verification] PPV on these components."
Stringer edge steps, as one veteran composite engineer explains, comprise the stacks of the composite fibers that make up the longitudinal structure that is cured and bonded to the skin of the fuselage barrels to give it its strength.
The letter goes on to detail the recommendations for the proper step height of each layer of composite fiber, plus or minus a given tolerance. The letter says that the guide for building fuselage stringers includes a note that says that step heights beyond a given a specified tolerance "will lead to significant degradation of the structure."
The tolerances and dimensions of the stringer were specifically outlined in the letter and are not included in this report due to the proprietary nature of the information.
However, the letter continues:
"Boeing engineering evaluations of the cross-sections provided by Alenia demonstrate that negative margins exist in the line 7-19, and line 20 and on, configurations for section 46. Line 5 and 6 are still under evaluation. While efforts are underway to refine that analysis, it is doubtful that the negative margins will be recovered, and that repair of at least line 7-29 will be required."
Of those 25 shipsets, four have been delivered to final assembly in Everett, Wash, eight are undergoing center fuselage integration at Global Aeronautica in Charleston, S.C. and the remaining 13 are in Grottaglie, Italy.
Each 787 barrel section contains 80 stringers that run the length of the fuselage. The letter did not detail what portion of the 80 would require repair.
The size of the edge steps on the stringers, the letter says, were increased first on "line 5 when Alenia began using the GFM stringer manufacturing cell at Grottaglie."
Line 5 refers to Airplane Five or ZA005, the first General Electric GEnx powered 787, that entered final assembly in January of this year. Sections 44 and 46 were delivered by Alenia for integration at Global Aeronautica in April 2008.
GFM is a company that does milling, cutting, routing and forging of various materials, including composites components.
During the manufacturing process, the composite stringers are fabricated in a clean room, loaded onto the preformed mold, or mandrel, then are wrapped in a preset amount of carbon fiber tape. After lay-up, which is done by a robotic wrapping machine, the mandrel is bagged and moved to the autoclave for high temperature curing.
Boeing's instructions in the letter to Alenia was to complete any carbon fiber placement currently underway, but not to begin any additional bonding or curing of barrels.
According to the letter, specifications were authored to control the height of the "edge step" as a result of what was learned during preproduction verification (PPV). The letter states that Alenia determined it "cannot comply with the requirement" and had requested "that the step height control provisions be eliminated." Boeing concluded that "based on the structural analysis...this is unacceptable" because the wrinkles "represent a risk of a major repair to every unit that is built without engineering coverage."
Boeing's conclusions on this structural analysis were conducted on two scrapped barrel sections identified as being from Airplane 15 section 46 and Airplane 20 section 44. "Sections cuts from the scrapped AP15 barrel show wrinkle geometry well in excess of those found during the PPV." Adding that the specification "does not allow wrinkles in the skin, and the existing effects-of-defects data does not sufficiently characterize the structural performance of wrinkles of this magnitude."
Boeing has yet to provide a revised schedule, known internally Z18, that dictates the 787 production and delivery schedule to suppliers and airline customers. The company has said a revised planning schedule will be available by the end of September.
This structural issue appears to not affect the first flight planning for ZA001 through ZA004, but it is yet unknown if delivery planning of the early production aircraft will be impacted while this issue is being resolved.
This shouldn't affect first flight of the aircraft already built and are awaiting wing box reinforcement, but this will impact first deliveries by another 6 months at least, on top of the already 2 year delay.
And I was laughing at Airbus for their A380 wiring problems...
“And I was laughing at Airbus for their A380 wiring problems.”
Building a composite aircraft is still a fairly new science.
Designing and installing wiring in aircraft is definitely not a new science.
Theres a huge difference.
True, but farming out the design and manufacture of such new science to companies such as Vought and Alenia was a big gamble on Boeing’s part, and it looks like it isn’t paying off.
Wasn’t a gamble it was politics. Other countries had to be involved, and other companies because of this fair world we live in...
It’s turned out to be terrible having this thing have different parts created in different parts of the world by different companies.
Yeah but you've got to admit the wiring problem was pretty unbelievable. From what I read they switched from copper to aluminum wiring but forgot to allow for a difference in the required bend radius of aluminum.
It is not as simple as that, the A380 problem was related to design collaboration tools. The A380 structure people were not informed correctly of a change to wiring bundles. To save weight the wiring harnesses were changed to use aluminum. This cause an increase in the total wire bundle diameter. The structures group was not informed of this change due to a design system tool flaw between the German and French designers. As a result the wire harnesses were too tight for the pass through holes in the interior ribs of the aircraft. The 878 problem is a design problem specific to composites. Just sayin.
Plastic airplanes belong on desks and hanging from ceilings, not carrying hundreds of people with structures as important as pressurized fuselages with no historical track record. Aluminum and rivets, with all their known drawbacks, have decades of successfull history.
Boeing has bet the farm on this thing and without a Obammy bailout may lose.
The 787 is a technical marvel designed by the leading aircraft designer in the world.
The A380 is another version of existing planes designed by a socialist backed job program.
I’d rather fly on a boeing than an airbus any day.
Stick it buddy. I was fabricating carbon fiber parts for Indy cars 20 years ago. In case you don’t know it the term plastic has been used for fiberglass and carbon fiber race car parts since before I arrived on the racing scene in 1971.
I don’t fly anyway, but there’s just too much euro parts in this thing for me. I’d certainly avoid one if I flew.
Yep, yep I do know quite alot about them. As far as aircraft use I am not aware of it being used for complete PRESSURIZED commercial aircraft fuselages. Do you? For control surfaces, panels, etc. they are perfect.
When the field test for delamination consists of tapping with a quarter and listening for audible differences is changed to a more scientific method I will become more of a believer. When thousands of pressure cycles, inspections, and decades of successful flight operations are completed I will become more of a believer.
The Comet exibited what can happen when things are overlooked and we do not need a 787 coming apart with 300 or so souls on board, perhaps, even several aircraft. I know, I know, the computers say it can’t happen but the computers are only as good as the people programming and running them. People are involved in making this thing and they can make either design or manufacturing mistakes as well as field service/inspection/maintenance mistakes.
Boeing is “all in” on the 787. They did the same on the 707 and 747 and came out very, very big winners. Only time will tell if they win big again or lose the farm. Only time will tell if the payload, economy figures and aircraft lives are correct. I just know I nor my family will never fly on a plastic airplane.
PS-Airbus still has a problem with their composite tails falling off.
That is all.
Haven’t seen 300 people in a butane tank at 35,000 feet doing 600mph yet. Have you?
I don’t care what the computers say, time will tell and Boeings future rides on it.
The Hawaiian 737 made it back on the ground, with good ole fashioned aluminum. Forgot how many thousands of cycles it had.
Enough on this tired old subject. We will discuss this later whether the fuse’s splinter apart into a million pieces killing hundreds or lasts for 40 years. Oops, will have to last longer than that, we got B-52’s older than that still flying.
I know...I am fitting some updates onto the fleet, right now....
Major league PITA using 1940’s technology on 21st century advanced composites....
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