It's easy to be a naysayer and express doubts about the world. A lot of times you might be right and look like a hero. And no one has ever been fired for crying wolf. It just might help some government wonk build an empire to put another bureacratic drag on business in North America. The business of negativity isn't what put people on the moon or won the wars. We'd still be debating the safety of crawling out of the swamp onto dry land.
The only thing I haven't heard much about is the comment that a previous poster made about the time variable of composites. However, I believe Boeing knows all about the previous failures of composites in aircraft and have accounted for the reasons. They would be crazy not to!!
Scientific caution is one thing, but saying it ain't gonna work just because....(fill in the blanks with old information or plain hot air) is another.
Why is the GAO wasting the money I have paid in taxes to double check the work of other governtment agencies that I also fund? The GAO should be spending all its resources trying to audit plans and programs going through Congress, not do the work of the executive branch.
When I first designed with compsites I reviewed all of the technical strength data. It was impressive. Then I discovered that composites degrade over TIME. The plastic resin becomes brittle and fails without warning due to plasticizer outgassing. Just like the Airbus A305 Rudders that have failed 3 times so far. Hundreds killed. The Dreamliner will be OK for a few years then suffer catestropic airframe failure in flight just like the American Airlines flight from JFK in 2001. No nondestructive testing can detect the impending failure. The FAA knows theis after dissecting the Lear Starliner composite aircraft that were removed from service. The FAA has a vested interest in protecting Boeing's investment in a failure prone aircraft generation. Metal aircraft can be inspected for cracks and the parts replaced before ultimate failure. It happens every month with no fanfare. My personal Cessna aircraft had 10,000 hard hours with no problems. A Piaggio 180 all composite aircraft in the same shop had countless cracks at 700 hours.
Not to downplay any existing safety concerns, but this study was done by the Government Accountabilty Office. I don't believe they have the technical expertise to declare anything safe or unsafe. That is the job of the FAA. Any part of an airplane must be approved by the FAA, whether they are deemed "Flight Safety" or not. The GAO can audit the FAA procedures and raise concerns, but it is Boeing, the FAA, and the operators who must develop and validate the repair and maintenance procedures.
Composites have been used in previous models, just not to the extent that they are in this airplane. It's not completely untrodden ground. All parties involved have been in communication throughout the design process and I doubt that these are new concerns. I'm guessing that within a short time the FAA and Boeing will produce existing documentation showing that maintenance procedures have been addressed at the design level. Some additional training or procedures for maintenance personnel may be the result of the study.
Using light strong fibrous composites to build an airplane. How novel! Ideas like that don't grow on trees. Or do they?
But in all seriousness, the problem of repairing composites, including wood has always been a pain. It is distressing that Boeing, especially with their history of wood structures would ignore the fact that some day some poor bastard would have to fix the thing.
The trick is being able to understand the "stresses" and stress points in the composites and this will take time to understand (history). Once these are understood and easily located (X-ray spectroscopy, etc), the problem areas can be fixed and/or maintained/replaced quite easily. My concern is do they have enough history to know how the components react to continual stresses and flex fatigue???
I read the concern being that the FAA does not have a strong data base and of set of protocols for planes made of higher percentages of composite materials, not that the plane is not safe or composites are not good. It is a who came fisrt/ chicken or the egg: safety protols for repairs have been established over the years based on 1.) materials used in plane (higher perecentage of metal vs. composites) and 2.) issues that have driven closer inspections in the filed (failures). Years ago, people said steel strong - steel good, and when aluminum and titanitum as lighter weight materials were introduces, people rightly questioned do we have adequate checks in place to insure these lighter weight materials will perform. Now the same questions are being asked about composites. I think it is just evolution, and the protocols for inspection of higher percentage use of composites will come as a natural necessity.
I am kind of interested in the way the report makes it sound like the GOA has safety concerns. But then they make it sound like the concerns are not huge safety risks. And they are not insurmountable. But does the FAA have the proper procedures in place to overcome this issues? And the GOA is not sure. As a frequent flier I guess I'de feel a lot more comfortable if someone would get together and make some kind of statement. This sounds like two government agencies that are not communicating that may in fact be doing the same job.
I agree that I am surprised the FAA would not be looking at the designs as they go along much like UL does. I would expect them to come in, do a little preliminary review and then recommend the tests that should be performed before the product is allowed to be used.
Or if that did happen why this group would then review the Dreamliner and bring out concerns. Something just doesn't sound right. I kind of feel like we are not hearing the entire story.
I've worked on parts and assemblies before and there are parts that are designated as Critical to Quality. You would think that list on an airplane would be kind of big and I can't believe there are things that are "not encouraged" by the manufacturers that companies actually do as part of their standard process. However, it's not tough to believe that with the tough economic times that we are all under, that proper training is not always done and procedures are not necessarily followed.
Linear guides are one of the most important components required for the development of automated or computer-controlled equipment. Aluminum profile extrusions, used for these guides in machine design, can enable designed-in functional features.
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