NAV20 From Australia, joined Nov 2003, 7136 posts, RR: 40 Posted (2 years 4 months 2 weeks 6 days 18 hours ago) and read 16103 times:
Many issues raised on A. net remain mysteries for a long time - so I thought that it would be worthwhile posting Mike Bair's 'full and final' explanation of the mysterious 'gap.' Turns out that it wasn't bad design or bad workmanship - just a case of components for one section of the first airframe (essential to holding its shape) not turning up on time and being fitted before it was transported:-
"Bair explained in detail the fuselage-gap problem.
"He said the forward fuselage built by Spirit AeroSystems of Wichita, Kan., had sagged and bulged outward in one quadrant after some secondary parts were late and not put in position early enough to hold the shape.
"The distortion was corrected in Everett. Engineers disconnected the internal structure and "pushed the bulge back in," Bair said.
"He said the issue would have been much harder to fix if the plane were aluminum, which is less flexible than the 787's composite plastic."
I'm sure it was just one of the many 'glitches' that Boeing and its partners will have to surmount as they struggle not just to get the aeroplane flying, but to move on to producing large numbers of frames in preparation for EIS. My own business field was major building construction, not aviation - but I'll still always remember the 'mad rush' to get everything on site and then the strange feeling of 'calm' (almost anti-climax, "What the hell were we all losing sleep over?") when the very last bit came off the truck and slotted perfectly into place.......
Mike Bair had a little fun at the end, with a play on words - mentioning what could prove to be not just Boeing's, but the whole industry's problem for some months to come - the worldwide shortage of fasteners:-
"Alluding to the shortage of fasteners, which he said is "a struggle" but not a showstopper, Bair said that the airplane program is close to its climax.
"The fundamental big bets have gone better than we imagined," Bair said. "We're into nuts and bolts, no pun intended, the little stuff."
NYC777 From United States, joined Jun 2004, 4291 posts, RR: 45 Reply 1, posted (2 years 4 months 2 weeks 6 days 18 hours ago) and read 15941 times:
Yup and you can bet that when these fuselage sections start getting to final assembly pre-stuffed according to the plan then fit issues will be non existent.
The first 787 will be standing on it's own landing gear tomorrow (June 22nd) so it has come a very long way in short amount of time.
Halls120 From , joined Dec 1969, posts, RR: Reply 2, posted (2 years 4 months 2 weeks 6 days 18 hours ago) and read 15863 times:
Quoting NAV20 (Thread starter): Many issues raised on A. net remain mysteries for a long time - so I thought that it would be worthwhile posting Mike Bair's 'full and final' explanation of the mysterious 'gap.' Turns out that it wasn't bad design or bad workmanship - just a case of components for one section of the first airframe (essential to holding its shape) not turning up on time and being fitted before it was transported:-
"Bair explained in detail the fuselage-gap problem.
"He said the forward fuselage built by Spirit AeroSystems of Wichita, Kan., had sagged and bulged outward in one quadrant after some secondary parts were late and not put in position early enough to hold the shape.
"The distortion was corrected in Everett. Engineers disconnected the internal structure and "pushed the bulge back in," Bair said.
"He said the issue would have been much harder to fix if the plane were aluminum, which is less flexible than the 787's composite plastic."
While I suspect many of the B haters will continue to insist that there is a B cover-up, or that B is ignoring icebergs looming in their future, it is refreshing to hear about an issue fully and frankly from the leadership of Boeing. Bair's statements are consistent with the "if we had a gap this small with an aluminum airplane, we'd have a party" statements attributed to unnamed B mechanics.
Poitin From , joined Dec 1969, posts, RR: Reply 3, posted (2 years 4 months 2 weeks 6 days 18 hours ago) and read 15810 times:
Quoting NYC777 (Reply 1): The first 787 will be standing on it's own landing gear tomorrow (June 22nd) so it has come a very long way in short amount of time.
Get a picture if you can. Sort of like baby's first step.
Bringiton From United States, joined Sep 2006, 784 posts, RR: 0 Reply 4, posted (2 years 4 months 2 weeks 6 days 18 hours ago) and read 15730 times:
Quoting NAV20 (Thread starter): The distortion was corrected in Everett. Engineers disconnected the internal structure and "pushed the bulge back in," Bair said.
That just sounds funny!!! remind me please who gets this aircraft so if i fly i will make sure i get seats that are farther back
Stitch From United States, joined Jul 2005, 15804 posts, RR: 63 Reply 5, posted (2 years 4 months 2 weeks 6 days 17 hours ago) and read 15597 times:
Quoting Bringiton (Reply 4): That just sounds funny!!! remind me please who gets this aircraft so if i fly i will make sure i get seats that are farther back.
Personally, I hope they fly LN1 to The Museum of Flight when done with the flight test regimen and put her in the airpark with a nice futuristic interior.
TeamAmerica From United States, joined Sep 2006, 1538 posts, RR: 18 Reply 6, posted (2 years 4 months 2 weeks 6 days 17 hours ago) and read 15597 times:
Quoting NAV20 (Thread starter): "He said the forward fuselage built by Spirit AeroSystems of Wichita, Kan., had sagged and bulged outward in one quadrant after some secondary parts were late and not put in position early enough to hold the shape."
Elastic deformation...just as I (and others) said in several overheated threads on this subject.
The problem was in the assembly procedure, not the parts.
Bbobbo From United States, joined Dec 2006, 183 posts, RR: 0 Reply 7, posted (2 years 4 months 2 weeks 6 days 17 hours ago) and read 15289 times:
Quoting Bringiton (Reply 4): Quoting NAV20 (Thread starter):
The distortion was corrected in Everett. Engineers disconnected the internal structure and "pushed the bulge back in," Bair said.
That just sounds funny!!! remind me please who gets this aircraft so if i fly i will make sure i get seats that are farther back Smile
Sounds like the 787 had a hernia.
By the way, if you Google "hernia", be prepared to cover your eyes.
Poitin From , joined Dec 1969, posts, RR: Reply 8, posted (2 years 4 months 2 weeks 6 days 16 hours ago) and read 15053 times:
Quoting Bringiton (Reply 4): Quoting NAV20 (Thread starter):
The distortion was corrected in Everett. Engineers disconnected the internal structure and "pushed the bulge back in," Bair said.
That just sounds funny!!! remind me please who gets this aircraft so if i fly i will make sure i get seats that are farther back Smile
Maybe they used a heat gun and shrunk fit the barrel
Stitch From United States, joined Jul 2005, 15804 posts, RR: 63 Reply 9, posted (2 years 4 months 2 weeks 6 days 14 hours ago) and read 14566 times:
Quoting Poitin (Reply 8): Maybe they used a heat gun and shrunk fit the barrel
Thought I saw an A340 depart PAE the other day. Perhaps they flew her in to back her up next to the 787 and let the four hair dryers hanging offer her wings warm it up a bit.
Ikramerica From United States, joined May 2005, 18390 posts, RR: 59 Reply 10, posted (2 years 4 months 2 weeks 6 days 13 hours ago) and read 14446 times:
Quoting Bringiton (Reply 4): That just sounds funny!!! remind me please who gets this aircraft so if i fly i will make sure i get seats that are farther back
"Not hyena! Hernia! Hernia!"
Of all the things to worry about... the Wookie has no pants.
Rheinbote From Germany, joined May 2006, 1534 posts, RR: 46 Reply 11, posted (2 years 4 months 2 weeks 6 days 11 hours ago) and read 14096 times:
"He said the forward fuselage built by Spirit AeroSystems of Wichita, Kan., had sagged and bulged outward in one quadrant after some secondary parts were late and not put in position early enough to hold the shape.
"The distortion was corrected in Everett. Engineers disconnected the internal structure and "pushed the bulge back in," Bair said.
"He said the issue would have been much harder to fix if the plane were aluminum, which is less flexible than the 787's composite plastic."[/quote]
I am seriously puzzled that nobody here challenges this lousy explanation.
1. A composite barrel cannot 'bulge in one quadrant' once cured. It may ovalize as a whole in case it is not (yet) properly stiffened. But 'bulge'? Local elastic deformation in one quadrant only?
2. "Aluminum is less flexible than CFRP"...what???
3. If there really was a bulge,e.g from a curing or mold defect, you can't just 'push it back in' with brute force (use of hydraulic press reported). That would leave the barrel joint non-uniformly pre-loaded and would severely limit the useful life of that part of the structure.
Maybe they just tried to find an explanation that is comprehensible for the layman. But this explanation given by Mike Bair is hogwash.
Quoting Stitch (Reply 5): Personally, I hope they fly LN1 to The Museum of Flight when done with the flight test regimen and put her in the airpark
If they really did what Bair described, then LN1 will end up there very quickly.
Ikramerica From United States, joined May 2005, 18390 posts, RR: 59 Reply 12, posted (2 years 4 months 2 weeks 6 days 11 hours ago) and read 14075 times:
Quoting Rheinbote (Reply 11): I am seriously puzzled that nobody here challenges this lousy explanation.
It's not lousy, it's layman. Know your audience, know the difference.
What he describes is quite plausible and logical, and just because you don't see it or you want highly technical terms to be used, doesn't make it less so.
Of all the things to worry about... the Wookie has no pants.
Astuteman From United Kingdom (England), joined Jan 2005, 6142 posts, RR: 84 Reply 13, posted (2 years 4 months 2 weeks 6 days 11 hours ago) and read 14018 times:
Quoting NAV20 (Thread starter): "He said the issue would have been much harder to fix if the plane were aluminum, which is less flexible than the 787's composite plastic."
This will be the same CFRP that's so rigid it doesn't need frames, presumably..........
Quoting Rheinbote (Reply 11): "Aluminum is less flexible than CFRP"...what???
Byrdluvs747 From United States, joined Jul 2004, 1179 posts, RR: 2 Reply 14, posted (2 years 4 months 2 weeks 6 days 11 hours ago) and read 13994 times:
Quoting Rheinbote (Reply 11): I am seriously puzzled that nobody here challenges this lousy explanation.
Here we go.
The 747: The hands who designed it were guided by god.
TeamAmerica From United States, joined Sep 2006, 1538 posts, RR: 18 Reply 15, posted (2 years 4 months 2 weeks 6 days 11 hours ago) and read 13892 times:
Quoting Rheinbote (Reply 11): A composite barrel cannot 'bulge in one quadrant' once cured. It may ovalize as a whole in case it is not (yet) properly stiffened. But 'bulge'? Local elastic deformation in one quadrant only?
Yes, when the remainder of the structure is restrained this is possible. Find a flexible ring of some sort and cup it in your hand, applying gentle pressure. Suppose that the portion held by your hand is the "desired shape"...leaving a bulge only in the portion not in contact with your hand. Add a rigid support to hold the ring in that shape, and you have an analog to what happened with the 787 fuselage.
Jerald01 From United States, joined Oct 2006, 161 posts, RR: 2 Reply 20, posted (2 years 4 months 2 weeks 6 days 10 hours ago) and read 12302 times:
Take any large-diameter (10 feet diameter or larger) ring-shaped object, whether it be made of aluminum or composite, load it onto a transport device (truck trailer, sled, pallet, etc.) horizontally, restrain it on that device, then ship it half a continent. Unless that ring-shaped object has some kind of internal bracing it will, to some degree or another, sag (I believe it was a Mr. Newton who "discovered" gravity, which is the culprit in this case.) Measure the diameter horizontally and then measure it vertically and see what you get.... two different diameters, right?
Large-diameter composite rings flex considerably if they are stood on their side. How do you get them back into a "round" shape if they are on their side? Opposing hydraulic presses work just fine, and they don't get in the way of whatever it is you are trying to mate the ring to (another fuselage section???). If done properly ther is no compromising of structural integrity of the ring or the composite material it is made of.
"There may be old pilots, and there may be bold pilots, but there are darn few green cows"
Airlinemodeler From United States, joined Oct 2004, 17 posts, RR: 0 Reply 21, posted (2 years 4 months 2 weeks 6 days 8 hours ago) and read 10809 times:
I doubt seriously that using brute force would be a technique used because the stress load in the area that the pressure was applied would have a serious compromised integral strength issue.
Stitch From United States, joined Jul 2005, 15804 posts, RR: 63 Reply 22, posted (2 years 4 months 2 weeks 6 days 5 hours ago) and read 9339 times:
Man, listening to some of the folks here you'd think Boeing connected 5X's 744F to the 787 fuselage section with chains and then went to max take-off power to yank the part into position.
I doubt the stresses were anywhere near as fierce as people believe or if they were, well Boeing just proved how robust a 787 fuselage barrel is and as such I would not be surprised to see the first controlled flight into terrain end with a huge trench being dug by the fuselage with everyone inside still sipping the champers in utter oblivion they'd just landed the hard way... (sarcasm smiley)
Pygmalion From United States, joined Jun 2006, 820 posts, RR: 32 Reply 23, posted (2 years 4 months 2 weeks 6 days 3 hours ago) and read 8378 times:
Think about a ring that is on the order of 58 Feet in circumference and on the order of a eighth of an inch thick from the photos. It would be very flexible if it was not supported.
Does anyone really expect a barrel to stay round if unsupported?? The stringers run longitudinally not circumferentially. The frames and floors must be installed to have the barrel hold its shape. Bairs explanation makes perfect sense.
And if you wanted to apply load carefully and slowly.. what would you use? A pry bar? Two guys named Guido and Bubba? Or a calibrated load cell with a hydraulic jack? Hydraulics are really nice in that they are very controllable and stable. Perfect for this.
Just because you can get one that will lift your car... doesnt mean that Boeing used a car jack. Anyone else ever use a Porta-power ram??
NAV20 From Australia, joined Nov 2003, 7136 posts, RR: 40 Reply 24, posted (2 years 4 months 2 weeks 6 days 3 hours ago) and read 8205 times:
Quoting Stitch (Reply 22): I doubt the stresses were anywhere near as fierce as people believe
Agree - it's not as if any force was 'captive,' any pressure applied would not have been borne solely by the section being reformed, it would be evenly-absorbed by the whole 'ring' - that's the whole point of making fuselages tubular.
One shouldn't forget that all airliner fuselages have (HAVE to have) incredible strength - since they're going to have routinely to resist forces of around six pounds per square inch all day every day from pressurisation once they're in service.
[Edited 2007-06-22 05:41:54]
"Once you have flown, you will walk the earth with your eyes turned skywards.." - Leonardo da Vinci
474218 From United States, joined Oct 2005, 3708 posts, RR: 1 Reply 25, posted (2 years 4 months 2 weeks 6 days 3 hours ago) and read 8205 times:
Quoting Pygmalion (Reply 23): Anyone else ever use a Porta-power ram??
How else are you going the remove the trunnion pins from the landing gear?
26 XT6Wagon: dynamite works I'm sure.... not to servicable after, but the pin would not be in your way anymore.
27 WestJetYQQ: About the Bulge; I've seen the 787 skin material up close. The composite material is very thin and strong, but i would be quite easy to make such a c
28 Aminobwana: I really am concerned by these insinuations. As I noted in the thread regarding the rumor of a crack in the A380 wing, such will not die if the manuf
30 Bringiton: On my part it was a joke ! Obviously any airframe put into testing would go through a rigourous testing regime and would be approved before acceptanc
31 Rheinbote: Guys, I'm neither sensationalist nor stupid. I am familiar with the concept of ovalizing. It is also pretty clear that a leightweight structure like S
32 JoeCanuck: It's not factually wrong...in fact, it's factually correct. If you compare how CFRP and AL pieces of the same thickness bend, you'll find that the AL
33 NAV20: I think that's the key, Rheinbote. As you imply, logic suggests that if there is a bulge in one sector (given that the circumference was correct, oth
34 Rheinbote: We are comparing aluminum and CFRP skins designed to similar requirements, not pieces of similar thickness. Aluminum skin on commercial aircraft is d
35 SailorOrion: What is "flexibility"? It's a term that is not really defined in material science. There's the modulus of elasticity, which basically tells you how mu
36 NAV20: Speaking as a fellow layman, Rheinbote - if you bend the piece of Coke can, it will stay bent and probably stretch and be permanently deformed. If yo
37 Rheinbote: Nice analogy, NAV20, but you're comparing plastic deformation ('stays bent') with elastic deformation ('springs back'). That's apples with grapes. But
38 NAV20: Please refer to #33 above, Rheinbote, I was the one who suggested that 'elasticity' was possibly a better term than 'flexibility.' As far as I can see
39 Khobar: Perhaps when dealing with coke cans (one piece); perhaps not when dealing with aircraft skins made up of many pieces of aluminum riveted together? AY
40 Ceph: Lets hope the plane doesn't blow up during pressure testing or after being subjected to many pressure cycles like the Aloha Airways 737 that lost a ro
41 Stitch: Not necessarily true. I was watching "How It's Made" on the Science Channel last night and they were showing how CFRP light-poles (for streets) were
42 Rheinbote: The pole was probably made from thermoplastic material which 'gets soft when heated'. In contrats, most CFRP composites used for aircraft primary str
43 Poitin: From what I heard, you are correct -- it is thermoset. However, it can be bent without deforming. All Boeing did was to remove some of the internal b
44 Astuteman: Provided the circumferential measurements were within spec, there should be absolutely no reason for this shape not to be correctable when unconstrai
45 Rheinbote: exactly. If circumferential/diameter measurements would be confirmed as within spec, the issue would be closed. The pitctures do not seem to support
46 Astuteman: If the circumferential measurements DO differ, you're well and truly screwed. All you'll do is chase the difference round and round the join. (My per
47 Aerodog: Mike Bair said, "... the forward fuselage built by Spirit AeroSystems of Wichita, Kan., had sagged and bulged outward in one quadrant after some secon
48 Tugger: Interesting, it sounds like the 787 is to previous aircraft/airliner production what uni-body construction in cars is to the previous body-on-frame ma
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Although that may not be futuristic enough.
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