There hasnt been a lot of discussion in our forum about the much troubled 787, so thought I would kick off a new line of thought about its problems.
According to reports, they heard the fastener problem during the pressure test on the static airframe.
Imagine up to 8,000 leaks, the sound must have been philharmonic to the ear.
Numerous reports and opinions around the websites as to the cause, and I feel a bit sorry for the maligned people on the assembly lines accused of not de-burring holes or inadequate chamfering.
I fear the problem lies elsewhere: namely in finding a way to relieve swarf building up between the frame and the composite barrel.
Most of the swarf of course travels up the drill flutes and is collected. I believe that sufficient swarf will escape into the space between the structures, and remain trapped, hence the air leaks because when the fastener is tensioned the swarf being titanium keeps the two surfaces apart, and no amount of sealant can compensate!
Interestingly Airbus opted for panels over barrels. Maybe this potential was one contributing factor, but If I am correct, IMHO Boeing will not be able to successfully assemble this aircraft using current methods?
I was just wondering where all these facts are coming from, according to certification tests conducted by Boeing, the 787 was subjected to 150% of the maximum pressure it would ever encounter, and passed with no leaks.
Does anyone have facts to support these claims, or are they just speculation and rumours?
Here's an interesting article from Seattle and workers comments, a couple of weeks old, but still relevent.
The dreaded Captain X of A.net fame who has been very quiet lately, just made a one line posting which went almost unnoticed saying that the leaks appeared during the pressure tests although it met its pressure limit ok.
This unknown guy or gal has been frighteningly correct in all his postings, and if the problem appeared on the static test frame, it makes sense.
Not verbatim, but the statement was that everyone could hear the leaks.
Frankly I have been so uncomfortable with the Boeing pronouncements about their problems I came to the conclusion that "no smoke without fire"
Now Bits, I have Fosters in my ref. so adios for now.
Nothing has been stated that the fasteners do not work if correctly installed. What it does say is new technology has its issues and not all of them are purely technical (implementation of technology being its own issue and the fasteners are new to eveyone).
As for comparing it to the A350 and saying that this is a possible reason why Airbus went with panels is beyond speculation, its fantasy.
Airbus cannot currently manfuature the type of fuselage Boeing elected to go with. As they have no experinc eiwht it, they know nohting about it that has not been learned by Boeing as they devleop it.
Panels are a totally unproven technique as well. They too will have various technical issue to overcome as well as their share of learning how to assemble them. Probably more so as Boeing does have a base of composite fuselage work others have done, their own extensive research and test articles (and they have with the V22 and military projects) to go by. Airbus has no such technical base with the panels and composite ribs (not to mention the hybrid section 42 with the aluminum ribs and composite panels).
This is another bump in the road for Boeing. If its meaningful in any way to Airbus, when they go to the spun composite fuselage it will be the beneficiary of lesson Boeing and industry leaned during the 787 project.
RC20,
I think your opening para was spot on, it is implementation that is the issue, and IMHO they are scratching around trying to solve the swarf issue. With a barrel you cannot simply ease it and clean it as you can a panel. The barrel once it has a few fasteners installed is firmly in place and cannot be moved to remove what I regard as"rogue" swarf which impinges between the barrel and the frame.
I had a laugh about your fantasy statement.
The only issue for the Airbus method will be substituting composite panels for metallic and/or glare panels, and they will be much bigger, but technically very low risk.
However, I totally disagree with both of your contentions.
Fasteners:
Boeing has understood all along that some will have to be replaced at some point. While they really mucked it up with this many, the technology is in place to drill them out and replace them. A big pain, a lot of work and money.
To try to make a case otherwise is simply wrong. Aircraft are hit by things all the time, and Boeing would not have bee en able to sell the 787 if they did not have plan in place to repair not just damaged barrel (patch, which is what Airbus will do with the panels), but the stringers and the associated fastener. A forklift hit at that point is going to damage all three.
Note they have done this once already on a very small scale when a worker installed a number of hem wrong in Charleston.
Panels:
You seem to have bought into the propaganda that Airbus put out that panels are better than spun (note that Airbus has said the next plane after the A350 will be spun fuselage).
Panels are simply the only technology that Airbus can employ in a reasonably time line that is composite based, so that is what they are doing. (unlike Boeing they did not put any research into an all com0posite aircraft, expectign it to evolve much slower).
That said, Airbus has no experience with this, and they are facing multiple issues that have never been done. Its a total technical leap for them, and just like Boeing, they will have to develop the materials (composite stingers, panels and fasteners) and techniques to attach the panels composite stringers as well as the strange decision to use aluminum in Section 42. That.s another whole different technology.
What is the difference in a fastener that goes into a composite or aluminium stringer, vs a titanium one? And, what does the panel change on that? The panel adds one other issue, the seams, as you are going to have some kind of stringer for the horizontal seams (vertical ones using the barrel stringers).
So, follow me down the path of logic. Airbus finds out it has fastener issues (and just for fun speculation, lets say this this develops after its in service). Are you telling us that they are going to replace an ENTIRE PANEL when there is three bad fasteners in the middle of it? And if you remove the panel, you still have the holes through your stingers to deal with.
What you have presented is a red hearing. Like Boeing, if Airbus has fastener issue or damage, it will remove the fasteners in that area, make a patch, install new fasteners and go on. You will never see a panel removed unless a substantial portion of the panel is defective (and that would be an enormous issue in of itself and how many etc). A panel changes nothing vs a spun barrel other than being heavier.
Each faces their won challenges. Neither is immune. Boeing has pushed the envelope harder in some areas, and will continue to encounter issues. I continue to believe that the biggest issue was being able to spin the fuselages barrel sections reliably and in quantity was the biggest. By all information, they have succeeded.
The barrels were all new. Panels have been done on wings and non pressurized sections. Never on a pressurized section of the fuselage. That creates a whole possible host of weaknesses that have to be worked out to ensure no issues. To contend that Airbus is doing this due to superior knowledge or technology is totally misleading.
I don't say they can't make it work, I do say they have to prove it, and be able to consistently execute it. They are at the very beginning of their challenges, Boeing is getting close to the end of theirs.
It's hard to believe that all the deep inside knowledge of Airbus and Boeing seem to be known, I just can't believe it.
It's pretty simple, there are true or false rumours out there stating there are problems with the 787 frame. Airbus opted for panels (which they also had no experience or knowledge of) but should be simpler and lower risk. Whichever turns out better, i don't think we'll know before they both fly. One advantage of the spun barrel construction in my memory was the lower cost, not all to do with weight.
Talk about technology though, in today's world I don't believe that Airbus can't build a composite plane because they've never done one before. All it takes are skilled and experienced labour, and money, and nothing stops them from making something even better. Their concerns were obviously money, and time.
Airbus and Boeing build all their current aircraft(sans 787) using panels, its just the material change at issue.
CX, did you know that the A380 has more composite structure by weight and area than a 787.
Airbus are very well versed in composites, and the A400M is a composite airframe, just needs engines to fly!
As I stated earlier, its just methodology that is dogging the 787 IMHO. But, if I am correct, it may need some re-design to address the current problem. It must be obvious that so many leaks involve more than incorrectly installed fasteners. My view is that it is that they incorrectly prepared for installation by having the burrs and swarf left in situ because they cannot be reached.
achace wrote:Airbus and Boeing build all their current aircraft(sans 787) using panels, its just the material change at issue.
CX, did you know that the A380 has more composite structure by weight and area than a 787.
Airbus are very well versed in composites, and the A400M is a composite airframe, just needs engines to fly!
As I stated earlier, its just methodology that is dogging the 787 IMHO. But, if I am correct, it may need some re-design to address the current problem. It must be obvious that so many leaks involve more than incorrectly installed fasteners. My view is that it is that they incorrectly prepared for installation by having the burrs and swarf left in situ because they cannot be reached.
I don't really know but don't get me wrong, some members seem to know exactly what's going on inside Boeing and Airbus and why something is done and why something isn't. But anyway, it's hard to believe the 787 won't fly, but if some of the rumours about weight is true about the 787, A350 seems a better product.
achace wrote:Airbus and Boeing build all their current aircraft(sans 787) using panels, its just the material change at issue.
CX, did you know that the A380 has more composite structure by weight and area than a 787.
Airbus are very well versed in composites, and the A400M is a composite airframe, just needs engines to fly!
As I stated earlier, its just methodology that is dogging the 787 IMHO. But, if I am correct, it may need some re-design to address the current problem. It must be obvious that so many leaks involve more than incorrectly installed fasteners. My view is that it is that they incorrectly prepared for installation by having the burrs and swarf left in situ because they cannot be reached.
I don't really know but don't get me wrong, some members seem to know exactly what's going on inside Boeing and Airbus and why something is done and why something isn't. But anyway, it's hard to believe the 787 won't fly, but if some of the rumours about weight is true about the 787, A350 seems a better product.
Except that one (B787) has been designed and built; it's problems are known. The other (A350) has not yet been design-finalized or parts delivered and the plane bulit; it is still a paper design and any problems (inevitable) are unknown. Let's wait and see how it all shakes out.
smokejumper wrote:Except that one (B787) has been designed and built; it's problems are known. The other (A350) has not yet been design-finalized or parts delivered and the plane bulit; it is still a paper design and any problems (inevitable) are unknown. Let's wait and see how it all shakes out.
Actually, haven't 6 been built or are in various stages of final assembly? I believe airframes 1 through 4 are on the assembly line and 2 static test airframes have been moved to their respective test locations.
