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Faro
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Wed Jun 24, 2009 7:36 am

I have always wondered why airliners have their wings attached to the fuselage sides. Would you not have a stronger structure if the wings were directly attached to each other at the fuselage centerline instead (ie, with no distinct wing box, only two structural halves), and the wing structure remaining monolithic and unimpaired at the fuselage sides?

Is this done for ease of manufacture?

Faro
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jetmech
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Wed Jun 24, 2009 8:12 am

Quoting Faro (Thread starter):

The two visible wing sections are in fact joined to a carry through structure. Thus, in essence, the wing is a one piece structure from wing tip to wing tip. The fuselage has a large cut-out in it to accommodate the wing, and basically sits on top of the wing centre section.

On the 747 for instance, there are three fuselage frames that attach to the top of the wing centre section at either end of the frame. Thus, there are six main attachments between the fuselage and wing.

The photos below show the removal of the visible sections of the wing from the centre section. The fuselage actually sits on the centre section, which carries through the entire width of the fuselage.

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Click here for bigger photo!

Photo © Willem Honders
View Large View Medium
Click here for bigger photo!

Photo © Willem Honders


You can see that Boeing also builds the 747 wing in the reverse manner. As you say, it probably does ease the manufacturing process to make the wing in three pieces, with appropriate attention being paid to the design of the joining interfaces.



http://blog.seattlepi.com/aerospace/library/747dash8wingsjoined.JPG

Regards, JetMech

[Edited 2009-06-24 01:14:02]
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Faro
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Wed Jun 24, 2009 8:23 am



Quoting JetMech (Reply 1):
The two visible wing sections are in fact joined to a carry through structure. Thus, in essence, the wing is a one piece structure from wing tip to wing tip. The fuselage has a large cut-out in it to accommodate the wing, and basically sits on top of the wing centre section

Wow, thanx for the pix!

If the wing is a one-piece structure however, wouldn't this be even stronger (and perhaps lighter) if it were a one-joint one-piece structure instead of a two-joint one?

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Wed Jun 24, 2009 8:34 am



Quoting Faro (Reply 2):

No worries. I think the only current commercial type where two aerodynamic surfaces are joined directly on the centreline is the tailplane of the 777.

Quoting Faro (Reply 2):
If the wing is a one-piece structure however, wouldn't this be even stronger (and perhaps lighter) if it were a one-joint one-piece structure instead of a two-joint one?

You can pretty much design in as much "strength" as you require, with a weight penalty of course. So yes, I suppose a single piece wing would be lighter for a given strength.

I suspect however, that the bending moment in the wing would have its highest magnitude at the centre line, thus, a single joint at this location may need to be more substantial compared with joins at the fuselage sides. Thus, the weight advantage may not be as obvious as it seems.

Regards, JetMech
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Wed Jun 24, 2009 10:39 am



Quoting JetMech (Reply 3):
I think the only current commercial type where two aerodynamic surfaces are joined directly on the centreline is the tailplane of the 777.

Don't know if i understand that correctly but, doesn't Airbus assemble on all planes the horizontal stabiliser joined into the airframe?
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Wed Jun 24, 2009 11:56 am

The wings are attached to a Torque Box.

See The Term Torque Box (by HAWK21M Feb 28 2009 in Tech Ops)
 
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Thu Jun 25, 2009 1:26 am



Quoting Faro (Thread starter):
Would you not have a stronger structure if the wings were directly attached to each other at the fuselage centerline instead



Quoting Faro (Reply 2):
If the wing is a one-piece structure however, wouldn't this be even stronger (and perhaps lighter) if it were a one-joint one-piece structure instead of a two-joint one?

Not stronger, but lighter. Normal design practice is that the joints are always stronger than the rest of the structure, so the joints actually increase, not decrease, strength. However, you pay a horrible weight penalty for that.

Quoting Autothrust (Reply 4):

Don't know if i understand that correctly but, doesn't Airbus assemble on all planes the horizontal stabiliser joined into the airframe?

The horizontal stab on Airbii is like Boeing...it goes right through the fuselage as a single structural member (it may be built in multiple pieces though).

Tom.
 
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Thu Jun 25, 2009 3:48 am



Quoting Autothrust (Reply 4):

A lot of commercial types appear to have horizontal stabilisers that are made of three parts. They are the two visible parts, and a centre section carry through structure. Thus, these designs represent a shallow "C" shape, such as the 747, and have two major joins.
Apparently with the 777 horizontal stabiliser, the two visible parts join directly to each other, without an intervening centre section, thus, these designs resemble a shallow "V" shape, and have a single major join.

Quoting Autothrust (Reply 4):
Airbus assemble on all planes the horizontal stabiliser joined into the airframe?

Yes, as TDs notes, the tailplane is assembled into one single piece. This is then attached into the fuselage. Most tailplanes attach via pivot points on the rear spar, and to a jackscrew on the front spar, but there certainly are exceptions. Apparently, the L1011 tailplane was mounted entirely on jackscrews alone.

Regards, JetMech
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Thu Jun 25, 2009 8:46 am

Quoting Tdscanuck (Reply 6):
Not stronger, but lighter. Normal design practice is that the joints are always stronger than the rest of the structure, so the joints actually increase, not decrease, strength. However, you pay a horrible weight penalty for that.

Thanx for the feedback; is this also the case with CFRP wings? Can you do away with jointed wings altogether with CFRP given its greater fatigue resistance?

Also, is it normal for airliners to have their wings removed for maintenance as pictured with the above-pictured KLM 747 or is this done in special cases only (to ascertain any damage after heavy landings for example)? This seems to be one hell of a procedure to go through...

Faro

[Edited 2009-06-25 01:51:33]
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Thu Jun 25, 2009 11:09 am



Quoting Faro (Reply 8):

Thanx for the feedback; is this also the case with CFRP wings?

In general, yes. You still want the joint to be stronger than the rest. You can do less joints on a CFRP wing because of the manufacturing method though. Metal wings are made from metal billets, so your largest part is limited by the largest billet you can get, which is limited by the metal mill and transportation concerns. For example, each wing skin on a large jet is usually 2/3/more individual skins spliced together because you can't economically get aluminum billets that are wide enough and deep enough to do an entire skin at once.

Since CFRP is built-up, rather than cut-down, there's no manufacturing limit on the initial part size other than your autoclave.

Quoting Faro (Reply 8):
Can you do away with jointed wings altogether with CFRP given its greater fatigue resistance?

The fatigue resistance issue is somewhat separate from the joining issue. Joining is purely a manufacturing (and sometimes maintenance) issue that's somewhat independent of the material. If you could get large enough billets, or big enough autoclaves, you could do single-piece wings with either technology.

Fatigue is the major reason the joint has to be stronger for metal wings. Joints always have stress concentrations, and stress concentrations cause huge drops in fatigue life. As a result, in order to meet fatigue requirements, metal joints on wings will almost always be grossly overstrength. CFRP has better fatigue properties, so this penalty shouldn't be a severe, but the countervailing factor is that CFRP doesn't take point loads (bolts/rivets/etc.) as well, so joints are more challenging.

Quoting Faro (Reply 8):
Also, is it normal for airliners to have their wings removed for maintenance as pictured with the above-pictured KLM 747

No. That particular case was done for transportation reasons, not maintenance. There's no normal maintenance procedure that would remove the wings. You'd only do it for non-normal repair and, even then, the economic case would be pretty tight I suspect.

Tom.
 
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Thu Jun 25, 2009 11:20 am



Quoting Tdscanuck (Reply 9):
If you could get large enough billets, or big enough autoclaves, you could do single-piece wings with either technology.

Thanx for the feedback. I guess one inevitable question is why didn't Boeing (and why won't Airbus I imagine, with the A350) set up the wing-building facility next to the main assembly line for the 787 and do all the wing work including autoclaving in-house. They could then have designed a one-piece wing. Unless of course the economic argument in favour of farming out the work was irresistible...

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Thu Jun 25, 2009 1:38 pm



Quoting Faro (Reply 10):
I guess one inevitable question is why didn't Boeing (and why won't Airbus I imagine, with the A350) set up the wing-building facility next to the main assembly line for the 787 and do all the wing work including autoclaving in-house.

I think you answered your own question:

Quoting Faro (Reply 10):
Unless of course the economic argument in favour of farming out the work was irresistible...

I suspect there's strong political component in there too. In Airbus's case, wings are the major British contribution to Airbus assembly. They need the Brits happy, and taking the wing away would not keep them happy. In Boeing's case, I don't think it's a coincidence that the launch orders came from the country who got the wings.

Right after Mike Bair left the 787 program, he had a lunch with some local business group (Everett Chamber of Commerce?) and opined that he's like to see a "supersite" where suppliers were colocated with final assembly. In that case, I think it was more about supplier oversight than part size & transport, but there would be obvious logistics advantages.

Quoting Faro (Reply 10):
They could then have designed a one-piece wing.

Yes. However, even if you did it on site I'm not sure it would economically work. A single-piece aluminum wing would require that you be on-site with the aluminum plant, and those are highly geographically constrained. It would also require some machining equipment on a scale that, as far as I know, doesn't exist today. A more tractable solution might be one-piece upper and lower skins and one-piece spars but, even then, I think you'd have to be on-site with the aluminum plant.

One-piece CFRP would be a lot easier on the materials side, but the mandrel for a one-piece barrel is already pretty complicated. The mandrel or mold for a one-piece wing would be a pretty phenominal piece of technology in its own right. One-piece skins are what we've got now, and I wouldn't be at all surprised if we get to one-piece spars in the near future (A400M might already have it, I'm not sure).

Tom.
 
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Thu Jun 25, 2009 4:24 pm

In a similar way, sailplanes have a 3-piece wing (or more, depending on the design of the wing) as well. Since a sailplane's wings are specifically designed to detach, there are heavy structural pieces on the root that interface with a wingbox in the fuselage itself, where the bolting/securing takes place. When the wings are secured, all three pieces are engineered to act as one.
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Quoting JetMech (Reply 7):
Apparently, the L1011 tailplane was mounted entirely on jackscrews alone.

The L-1011 horizontal stabilizer (tailplane?) has no jsckscrews. It is attached to the aft-body by two bearings and moved by four hydraulic actuators. On the L-1011 jackscrews are only used for secondary controls (slats and flaps).
 
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Fri Jun 26, 2009 8:49 am



Quoting Tdscanuck (Reply 11):
One-piece CFRP would be a lot easier on the materials side, but the mandrel for a one-piece barrel is already pretty complicated. The mandrel or mold for a one-piece wing would be a pretty phenominal piece of technology in its own right. One-piece skins are what we've got now, and I wouldn't be at all surprised if we get to one-piece spars in the near future (A400M might already have it, I'm not sure).

In effect, the technology is not yet here, but is not impossible to implement. Maybe a one-piece wing for the 737/777 replacements one day...

On a sidenote, in many ways, all future CFRP airliners are indebted to the pioneering efforts of Boeing on the 787. In effect, it is the sole member of the 1st CFRP airliner generation. The A400M, A350 and others will have the free benefit of the knowledge of all its development problems, that they may better avoid them in their own endeavours.

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Fri Jun 26, 2009 9:06 am

I recall an interview with Burt Rutan where he said GlobalFlyer's wing was one piece. No joins. Thus lighter and simpler in structure. All composite of course.


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Sat Jun 27, 2009 7:58 am



Quoting 474218 (Reply 13):
The L-1011 horizontal stabilizer (tailplane?) has no jsckscrews. It is attached to the aft-body by two bearings and moved by four hydraulic actuators. On the L-1011 jackscrews are only used for secondary controls (slats and flaps).

Fair enough. Can you give more details on the operation of L1011 horizontal stabiliser and elevators? I remember reading that it is an all flying surface, and the elevators are geared into the movement of the tailplane. Is this what actually happens?

Regards, JetMech
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Sat Jun 27, 2009 7:00 pm



Quoting JetMech (Reply 16):
Fair enough. Can you give more details on the operation of L1011 horizontal stabiliser and elevators? I remember reading that it is an all flying surface, and the elevators are geared into the movement of the tailplane. Is this what actually happens?

Here are a couple of sketches from an old training manual. Basically the four actuators position the stabilizer and the elevator is positioned by the cables/push rod. The stabilizer moves from nose up 1 degree to nose down 14 degrees.

The elevator is at 0 degrees when the stabilizer nose is full up and plus 24 degrees when the stabilizer nose is full down.

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Quoting 474218 (Reply 17):

Thanks for the info! That's a very interesting set-up. It appears that the horizontal stabiliser not only trims the aircraft, but controls pitch as well, with the elevators set up almost like an anti-servo tab. It's interesting to see that the power servos are physically separate from the actuator bodies. Most actuators I have seen have the power servo and actuator body as one piece.

I can only assume that given there are four feedback linkages, each actuator must operate independently. How is all this sequenced to operate in unison? What if one or more of the actuators fails or tries to go in an opposite direction to the rest?

Regards, JetMech
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Quoting JetMech (Reply 18):
I can only assume that given there are four feedback linkages, each actuator must operate independently. How is all this sequenced to operate in unison? What if one or more of the actuators fails or tries to go in an opposite direction to the rest?

There is a test that verifies the servos/actuators are working in unisonous. The "hysteresis test" shuts off the hydraulic power to each servo and the movement of the stabilizer is measured. If the difference between the two system is too high re-rigging is required.

While I can't think of a way to make an actuator go in the wrong direction, if it did happen the other three would simply over power it. Additionally, the actuator attach pins are designed to shear case of a actuator jam.

The L-1011 was designed to be operated safely with the loss of three of its four hydraulic systems. So full pitch control would be available with only one half of a servo and one actuator operating.
 
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Quoting 474218 (Reply 19):
Additionally, the actuator attach pins are designed to shear case of a actuator jam.



Quoting 474218 (Reply 19):
The L-1011 was designed to be operated safely with the loss of three of its four hydraulic systems. So full pitch control would be available with only one half of a servo and one actuator operating.

That's pretty impressive redundancy. Is there any reason Lockheed went for such a set-up, as opposed to something more "conventional"?

Regards, JetMech
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Mon Jun 29, 2009 9:28 pm



Quoting Faro (Thread starter):
wing structure remaining monolithic and unimpaired at the fuselage sides?

This is how CRJ's are built. the "wings" are actually one wing, attached to the fuselage by six or seven (I can't remember) Bolts, and faired in with composite secondary structure. The main spar is a single piece of milled aluminum. Some inspection during the life of the aircraft requires these bolt to be looked at, requiring the aircraft to be shored and bolts removed.
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Tue Jun 30, 2009 11:40 am

Small aircraft often have a two-piece wing with the fuselage on top (low wing aircraft only; Cessnas have a three piece wing); my next airplane (the Mooney) has a one piece wing. With large aircraft the center wing box is also the main landing gear support, and I think this is a big reason why they do it in three pieces. And while removing wings is a very infrequent occurrence on large aircraft, I suspect it would be nearly impossible with a two piece wing as opposed to very difficult with three. But I think that the landing gear is the main reason why they are all three piece; the landing gear support structure is much easier to build with the three piece structure..
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Tue Jun 30, 2009 2:19 pm



Quoting JetMech (Reply 20):
That's pretty impressive redundancy. Is there any reason Lockheed went for such a set-up, as opposed to something more "conventional"?

Best way to explain it: Boeing was ran by their production staff, Douglas their sales team and at Lockheed it was their engineering department.

Quoting Dc8friendship (Reply 21):
This is how CRJ's are built. the "wings" are actually one wing, attached to the fuselage by six or seven (I can't remember) Bolts, and faired in with composite secondary structure. The main spar is a single piece of milled aluminum. Some inspection during the life of the aircraft requires these bolt to be looked at, requiring the aircraft to be shored and bolts removed.

Could you provide a picture (or sketch) of the CRJ wing installation. I am having a hard time picturing how only six or seven bolts can attach the wing. I would think at the least the outer wing box stringers would have to be attached to the center wing box stringers for load transfer.
 
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Quoting 474218 (Reply 23):
Could you provide a picture (or sketch) of the CRJ wing installation. I am having a hard time picturing how only six or seven bolts can attach the wing. I would think at the least the outer wing box stringers would have to be attached to the center wing box stringers for load transfer.

The six or seven bolts hold the wing assembly to the fuselage, not the wings to the wing box. Load transfer between wing stringers is internal to the wing assembly.

Tom.
 
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Wed Jul 01, 2009 4:52 am

I need to add a few comments here.

There are a number of smaller aircraft that do have mantaince procedures that will require de-mating a wing.

The one I think we would be most familiar is the one that is required for Lears at 20K (40???) house of flight time

On a multi-piece wing the farther outboard the joints are the less massive the bolts holding it together. therefore the lighter it can be. It is under less stress. One small plane-the Navion instead of having a left and right hand joing just had one right in the middle of the span. One of my professors had one, very large bolts, but only needed 1 joint so it saved weight.
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Thu Jul 02, 2009 1:37 pm

OK with just six bolts holding the wing assembly to the fuselage how can they maintain pressure? I sure would like to see pictures.

Quoting Dc8friendship (Reply 21):
This is how CRJ's are built. the "wings" are actually one wing, attached to the fuselage by six or seven (I can't remember) Bolts,



Quoting 474218 (Reply 23):
Could you provide a picture (or sketch) of the CRJ wing installation.



Quoting Tdscanuck (Reply 24):
The six or seven bolts hold the wing assembly to the fuselage, not the wings to the wing box. Load transfer between wing stringers is internal to the wing assembly.

I am still waiting for a picture of these "six or seven" bolt that hold the wing on.
 
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Quoting 474218 (Reply 26):
OK with just six bolts holding the wing assembly to the fuselage how can they maintain pressure?

The wing's not pressurized. It's the fuselage skin that's holding pressure. It varies by aircraft, but I'd suspect most have a fitting outside the pressure shell for the wing to bolt to.

I haven't been able to find a good picture yet, but check out the cutaway of a Cessna Citation:
http://www.flightglobal.com/airspace...s/5722/cessna-citation-cutaway.jpg

You can see that the wing runs straight through under the floor. The pressure is held by the floor. The wing mounting would be between the wing upper skin and the fuselage floor.

Tom.
 
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Quoting Tdscanuck (Reply 27):
You can see that the wing runs straight through under the floor. The pressure is held by the floor. The wing mounting would be between the wing upper skin and the fuselage floor.

I could only find a cutaway drawing for the Canadair Challenger (the aircraft the CRJ's are based on) and its wing attach does not appear to look anything like that of the Cessna Citation. The Challenger wing installation appears to be similar to that of most large airlines. The outer wing box mates with the center wing box and they are attached to the fuselage frames and fuselage skin, with more than "six or seven" bolts, more like hundreds of high strength fasteners. The upper wing box and the fuselage skins are part of the pressure vessel.

http://www.flightglobal.com/airspace...81/canadair-challenger-cutaway.jpg

But if someone would show me a picture of the "six or seven" bolts that hold the wings on I am open to say "I was wrong".
 
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Sat Jul 04, 2009 2:45 pm

Quoting 474218 (Reply 28):
But if someone would show me a picture of the "six or seven" bolts that hold the wings on I am open to say "I was wrong".

B-727 in fact has 4 bolts attaching wing to fuselage as described in this thread, I've seen the video mentioned...

How Do They Fix Airliner Wings To The Fueslage? (by Ps76 Feb 17 2005 in Tech Ops)

A good pix here of the bolt hole on the prototype 727.. (scroll down a bit). Also if look closely you can the attach point on the fuselage as it "flies" overhead in another shot.

http://www.rbogash.com/727history.html

B-47 had a similar setup. The bolt was referred to as the "Milk Bottle" as it was similar in size and shape to a milk bottle.

[Edited 2009-07-04 07:57:45]

[Edited 2009-07-04 08:00:24]
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Sat Jul 04, 2009 2:57 pm



Quoting ZANL188 (Reply 29):
B-727 in fact has 4 bolts attaching wing to fuselage as described in this thread, I've seen the video mentioned...

I couldn't find the video?
 
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Sat Jul 04, 2009 3:07 pm



Quoting 474218 (Reply 30):
I couldn't find the video?

unfortunately no longer available at Amazon...

http://www.amazon.com/Building-Test-...UTF8&s=video&qid=1246719891&sr=8-1
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Quoting ZANL188 (Reply 29):
B-727 in fact has 4 bolts attaching wing to fuselage as described in this thread, I've seen the video mentioned...

So you are telling me that the wings on a B727 are held on with just four bolts?

"Amazing".
 
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Sat Jul 04, 2009 4:39 pm



Quoting 474218 (Reply 32):
So you are telling me that the wings on a B727 are held on with just four bolts?

"Amazing".

Yup. They were large though and I understand they were called "pins" vs bolts. Tolerances were extremely tight, the pins were shrunk with liquid nitrogen (or some other cryogen) prior to insertion.....
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Sun Jul 05, 2009 1:30 am



Quoting ZANL188 (Reply 33):
Tolerances were extremely tight, the pins were shrunk with liquid nitrogen (or some other cryogen) prior to insertion.....

That sounds more like an interference fit rather than tight tolerances, though the tolerance also may have been tight.
 
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Sun Jul 05, 2009 3:50 am



Quoting 474218 (Reply 32):
So you are telling me that the wings on a B727 are held on with just four bolts?

"Amazing".

Even the C-130 has 4 bolts that holds each wing on. There was a SB or a AD out recently on it to inspect it due to corrosion findings.


On the ERJ-145, there's a bunch of bolts that holds the wing to each other thru the fuse and each bolt is torqued down to over 1,000 ft/lbs!
 
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Sun Jul 05, 2009 9:18 am



Quoting 777WT (Reply 35):
Even the C-130 has 4 bolts that holds each wing on. There was a SB or a AD out recently on it to inspect it due to corrosion findings.

That was a TCTO and a bunch more than 4 bolts.
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larshjort
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RE: Wing-Fuselage Junction

Sun Jul 05, 2009 12:02 pm

As far as I remember each wing on the F-16 is held in place by 16 bolts.

/Lars
139, 306, 319, 320, 321, 332, 34A, AN2, AT4, AT5, AT7, 733, 735, 73G, 738, 739, 146, AR1, BH2, CN1, CR2, DH1, DH3, DH4,
 
474218
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RE: Wing-Fuselage Junction

Sun Jul 05, 2009 3:01 pm



Quoting 777WT (Reply 35):
Even the C-130 has 4 bolts that holds each wing on. There was a SB or a AD out recently on it to inspect it due to corrosion findings.

Suggest you review the following site:

http://www.asipcon.com/2006/06_proceed/Tuesday/0430_Bateman.pdf

If there are only 4 bolts holding on the wing why do "bolt hole eddy current" inspect over 300 fastener holes?
 
777wt
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RE: Wing-Fuselage Junction

Sun Jul 05, 2009 5:18 pm



Quoting 474218 (Reply 38):
Suggest you review the following site:

http://www.asipcon.com/2006/06_proceed/Tuesday/0430_Bateman.pdf

If there are only 4 bolts holding on the wing why do "bolt hole eddy current" inspect over 300 fastener holes?

I'll have to ask my boss for more info who was a mtx crew cheif for the USAF on the C-130's.

When I mentioend about the recent inspections on the wing bolts, he asked me if I knew how many bolts was holding the wing on...I said 'no, how many?" then said there's 4 bolts and to get access to them, you have to get into the wing and push the fuel bladder out of the way to get to them.

What I believe he's talking about is between the fuse and the #2 or #3 engine.
 
474218
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RE: Wing-Fuselage Junction

Sun Jul 05, 2009 5:35 pm



Quoting 777WT (Reply 39):
I'll have to ask my boss for more info who was a mtx crew cheif for the USAF on the C-130's.

Why not just look at photos in the site I referenced, it clearly shows that there are 24 bolts that attach the inner wing box to the outer wing box, just outboard of engines 2 and 3.
 
challengerdan
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RE: Wing-Fuselage Junction

Wed Jul 08, 2009 7:40 pm

Same set-up on the entire Challenger 600 series and CRJ.

Although i can't garantee for 700 series, but set-up is similar.

3 fittings on each side of the wing at a point 45 inches from the wing centerline.
They attach to the 3 of the bigger frames you see on the challemger picture, first, third and fourth. Think the second is just reinforcing for the emergency door.

There is a fourth point further inboard, at about BL 25 in the gear bay where the side stay actuators are mounted (different on the 700 and 900)

Add to this two keel beams, one fwd and one aft.

We are looking at 16 bolts, more or less, two dogbones links (of wich the bearings crack on the 900 series) and two tie bars, up front.

The multiple rows of high strenght fasteners you see on the pic are just the wing structure, nothing to do with the mating of the wing itself.

the actual wing is a one piece all metal primary structure, but it is composed of a center wing section with two reinforced bulkheads at about BL 45, where the two half wing spars are assembled. this area of high strength, where the spars attach to the center wing box (aux tank) are then mounted to the fuselage.

Somebody was reffering to the wing beeing pulled of a lear at 12k hours. same set-up, pretty much.

The fuselage keeps it pressure through what is approprietly called the preesure floor, that goes above all of the wing and the gear bay.

It is far from being an incredible setup in terms of fuselage fatigue, as it includes many right angles. Wasn't that much of a problem on the Challengers, but the CRJ is known to crack alot.

bulkheads 409 and 559, 621 (Actual aft pressure bulkhead), the square 4-faced engine torque box, etc....
if your flight goes MX in YUL, I might be called to fix it!
 
zanl188
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RE: Wing-Fuselage Junction

Sun Sep 20, 2009 11:20 pm

Happened to see these 727 disassembly photos on the Airplane Home website - thread currently running in Non-A.

In the very center of the first pix you can see the pin and surrounding structure that attaches the front spar to the wing box. Look just to the right of the disconnected duct.



Big version: Width: 2048 Height: 1536 File size: 109kb
Courtesy: Airplanehomes.com


In the second pix they have removed the wing by drilling out the fasteners surrounding the pin instead of removing the pin itself

Big version: Width: 2048 Height: 1536 File size: 76kb
Courtesy: Airplanehomes.com
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474218
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RE: Wing-Fuselage Junction

Mon Sep 21, 2009 1:34 am



Quoting ZANL188 (Reply 42):
In the second pix they have removed the wing by drilling out the fasteners surrounding the pin instead of removing the pin itself

How come there is no fitting on the wing that mates to the "pin"? In fact the front spar is contoured around the "pin".

If the "pin" attaches the wing to the fuselage, why did they have to "drill out" all those fasteners.

I think you will find that it is those drilled out fasteners (along with a lot of other fasteners) are what attaches the wing to the fuselage.
 
FX772LRF
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RE: Wing-Fuselage Junction

Mon Sep 21, 2009 4:58 am



Quoting Faro (Reply 2):
If the wing is a one-piece structure however, wouldn't this be even stronger (and perhaps lighter) if it were a one-joint one-piece structure instead of a two-joint one?

Really, I think the one of the main reasons larger jets don't contain a one-piece wing is because of transportation.

They already have a hard enough time transporting the A380 wings in two/three parts, imagine it as one!

Just my  twocents 

-Noah  wave 
Cleared to IAH via CLL 076 radial/BAZBL/RIICE3, up to 3k, 7k in 10, departure on 134.3, squawk 4676, Colgan 9581.
 
zanl188
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RE: Wing-Fuselage Junction

Tue Sep 22, 2009 12:10 am



Quoting 474218 (Reply 43):
I think you will find that it is those drilled out fasteners (along with a lot of other fasteners) are what attaches the wing to the fuselage.

Negative. They disassembled the wing vs removing the pin.....
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