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ANA (All Nippon Airways) was to receive the first 787 Dreamliner delivery in May 2008  (Source: Boeing)
Just days after saying that the Dreamliner would be on schedule, Boeing reverses its position

What a difference a few days make. On Monday, DailyTech reported that Boeing's 787 Dreamliner program was still on schedule. The ambitious airliner project has sparked much interest from aviation enthusiasts and has rallied Americans around Boeing, while European rival Airbus has been plagued with delays to its A380 superjumbo program.

Randy Tinseth, Boeing Commercial Airplanes Vice President for Marketing, reported that the program was still on schedule earlier this week. Tinseth remarked that despite supply issues, the Dreamliner program would meet its scheduled first delivery date in May 2008.

"It is still our objective to meet that May 2008 delivery but in doing that we have had to compress our flight-test schedule," said Tinseth on Monday. "It is an aggressive schedule but we believe we can do it."

Apparently, Boeing simply cannot live up to the statement made by Tinseth and the company today announced that it would delay deliveries for the Dreamliner.

The company blames out-of-sequence production on its test aircraft, parts shortages and software issues for the delay. As a result, initial deliveries have been delayed from May 2008 to November 2008 at the earliest.

"We are disappointed over the schedule changes that we are announcing today," said Boeing President CEO Jim McNerney. "Notwithstanding the challenges that we are experiencing in bringing forward this game-changing product, we remain confident in the design of the 787, and in the fundamental innovation and technologies that underpin it."

"While we have made some progress over the past several weeks completing work on our early production airplanes and improving parts availability across the production system, the pace of that progress has not been sufficient to support our previous plans for first delivery or first flight," continued Boeing Commercial Airplanes CEO Scott Carson.

The first schedule flights of the Dreamliner are now scheduled for the first quarter of 2008 instead of the revised mid-November to mid-December timeframe.


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RE: For the parts
By Keeir on 10/11/2007 2:11:46 AM , Rating: 4
quote:
While there have been lots of studies on composite materials in aircraft, there is still relatively little known about what happens to the materials when they are exposed to the stresses of flight day in and day out for several decades.


Speaking as an aero-structure engineer, I can say that the vast majority of current problems in commercial aviation are caused by inappropriate repairs and/or corrosion and wear. Which, thankfully, there is still a decade or more to answer for the 787.

The use of composite parts on previous -commerical- aircraft in both structural and non-structural applications is providing the data needed for the answers to these questions. For example, sticking within Boeing, the 767 and 777 have composite main landing gear doors, composite fairing panels, composite access doors, composite radome (very front of the aircraft), etc. Note, the basis for these composites are 20-30 year old materials. The truly unique application of composites for the 787 is using composites on the pressurized fuselage section of the aircraft, where the internal pressure loading is very severe. Most of the sections that would be experiencing extreme heat will (and are on current aircraft) made from special metals.

On current aircraft, the aluminum skins (special "high strength" aluminum that still 1/2 or less the strength of steel) undergoing pure pressure loading are in the range of 0.040" inch thick on most aircraft (some thinner some thicker) for perspective thats around 1 mm thick. They are pretty "soft" too (a softer metal cracks at a slower rate, but is more suspectable to surface damage). A man with a hammer or box cutter could cause serious damage to an aircraft. Corrosion is a real and powerful issue with metal this thin as well.

The composite structure promises to be significant more resistant to impact, cutting, abrasion, and corrosion. Yay, less damage! Composite structure is actually "easier" to repair and repairs stronger because the layers bond together, thus creating relatively low shear per inch load transfers in affected areas. Aluminum structure requires fastener load transfer (which creates stress concentrations and areas much more likely to crack under cyclic loading).

Although composites DO have issues with lightening strike damage (a normal aircraft will have thousands of lightening strike events in its useful life), on the whole, a composite aircraft -should- be safer to maintain and repair, provided airlines spend a little extra money on the damage detection side...


RE: For the parts
By FITCamaro on 10/11/2007 8:20:48 AM , Rating: 2
You know I never thought about lightning strikes until now.

What will happen to the composite material being used here if lightning strikes it?


RE: For the parts
By Keeir on 10/11/2007 12:16:57 PM , Rating: 2
The problem is that no one really knows for sure. Composite are not usually sections of the aircraft that experience lightening loading because lightening is looking for the path of least resistence and a round metal tube qualifies nicely. There is not really a great way to test this, although I hear Boeing has a facility that does pass huge amounts of voltage though composite sections.

The main concerns are two fold and Boeing is AFAIK (information from Flight Trade Mags and Seattle PI) working on solution to both

#1. Lightnening will be more attracted to fasteners which are made of metal. This could result is loss of several adjacent fasteners or local destruction of composite material (which would be the same thing as losing the fastener). Boeings Solution, A. Attempted to have composite fasteners (nixed due to something or other) and B. Sink critical fasteners below a layer of composite material, hopefully reducing the likely hood of lightening strike.

#2. Lightnening strikes will melt/disbond large regions of composites in the center of body sections. Boeings Solution: Sink a metal mesh into the composite fuselage to attract the ligntening and to conduct the lightening to the exit point. The concern here is that the metal mesh may have too high of a resistance (after undergoing damage from typical flight) and will heat up significantly during lightening strike (P=(i^2)R right?).

Before getting too fearful though, Federal Aviation Regulations state an aircraft must be able to fly and land with large amount of damage. Typically for metal aircraft this involves destroyed fasteners in critcal regions, large cracks that are 30+ inchs of fuselage, severed/destroyed internal structured combinations of the above. These same regulations will apply for the composite structure. Even if lightening turns out to be a significant problem, a crash is very unlikey to occur unless an airline is particular uncareful and not noticing large burn marks/disbonding regions. (Oh, Federal Aviation Rules also state each and every pilot must make a visual inspection of the aircraft before piloting the aircraft... you can be sure, they don't want to die. I have heard reports/stories of aircraft pilots refusing to fly until structural damage has been assesed and repaired)


RE: For the parts
By timmiser on 10/11/2007 3:03:50 PM , Rating: 2
I remember reading in the Seattle Times about the 787 and lightning strikes about a year ago. Apparently there is some type of metal mesh imbedded in the composites to account for just this issue.


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