Piper fuselage adhesive

GlennAB1 said:
No personal attack there....
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You don't believe telling the folks here a lie isn't personal attack when it says something that reflects on my integrity, isn't a personal attack?

maybe we should allow the board to figure it out.
 
Tom-D said:
What ? where would I get such a thing?
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images
 
Timbeck2 said:
Okay the plot thickens. The tech rep sent me a picture of the drawing and the stiffener (that's what I'm calling it because I don't know) isn't even depicted. He wanted to know if it was added later. There is no record of it. Waiting on words again.

This airplane ownership thing.... (insert smiley faced dude blowing his brains out)
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Quoted myself <giggle> what a nerd. :rolleyes:

Now I'm thinking the tech rep has the wrong drawing because two more Cherokee owners have sent me pictures of their airplanes with the stiffeners in place. So it is factory. Another thing, there is some sort of fabric under these things as well. I may have "discovered" something that was normal all along but my A&P doesn't think so. Still waiting on words from Piper.
 
Timbeck2 said:
Quoted myself <giggle> what a nerd. :rolleyes:

Now I'm thinking the tech rep has the wrong drawing because two more Cherokee owners have sent me pictures of their airplanes with the stiffeners in place. So it is factory. Another thing, there is some sort of fabric under these things as well. I may have "discovered" something that was normal all along but my A&P doesn't think so. Still waiting on words from Piper.
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Can you move this to see if it is wearing on the skin? IOWs is it loose?
 
I can't see any wear but yes, it is loose which brings up the question that if the fabric/material is there, is it supposed to be able to move?
 
Timbeck2 said:
I can't see any wear but yes, it is loose which brings up the question that if the fabric/material is there, is it supposed to be able to move?
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If there is no wear, don't mess with it. IOWs if it ain't broke don't fix it until it is.
 
Well, the cat's already out of the bag so to speak with Piper and my mechanic. Piper says this morning (via email) that it was "probably" bonded in an oven and the bond is coming apart. Not sure if that is the case since they didn't have the part in question on the drawing to begin with. Still waiting on a fix action. I feel like going out to the airport and pushing on every Cherokee I can find to see similar results to mine. Now I feel as if all the worms are crawling out of the proverbial can and I can't get them back in.
 
Timbeck2 said:
Well, the cat's already out of the bag so to speak with Piper and my mechanic. Piper says this morning (via email) that it was "probably" bonded in an oven and the bond is coming apart. Not sure if that is the case since they didn't have the part in question on the drawing to begin with. Still waiting on a fix action. I feel like going out to the airport and pushing on every Cherokee I can find to see similar results to mine. Now I feel as if all the worms are crawling out of the proverbial can and I can't get them back in.
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Isn't it really up to your A&P to make the decision as to how to fix?
 
Timbeck2 said:
Well, the cat's already out of the bag so to speak with Piper and my mechanic. Piper says this morning (via email) that it was "probably" bonded in an oven and the bond is coming apart. Not sure if that is the case since they didn't have the part in question on the drawing to begin with. Still waiting on a fix action. I feel like going out to the airport and pushing on every Cherokee I can find to see similar results to mine. Now I feel as if all the worms are crawling out of the proverbial can and I can't get them back in.
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Oven cured / bonded structures and even composite assemblies themselves are repaired using adhesives without an oven every day.

I've even seen an transport category airplane's rudder balance weight bracket removed from one skin and placed on another OEM purchased skin, only thing attaching it is adhesive, there are no fasteners used from the factory. Since this is a critical thing, flight control balance weight after all, third party engineering and FAA approval was obtained to do it.
 
Yes but he and I don't agree. He wants to put an entire row of rivets in the piece, I don't. The first picture with the blue sticky is where the rib is located and the second is the rib in question. The green rib is riveted (that runs through the right side of the U) but the silver one in the center is the one in question. The yellow stuff is 47 year old powder that used to be glue.
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I wonder how many other cherokees out there have the same issue. It would seem that if they're as old as mine then they ALL would have the same issue.

that is if it even IS an issue. :dunno:
 
What will it harm if the row of rivets are put in?
 
Nothing except what one guy said earlier (on page 1) about strengthening one part may weaken another would cause concern. In the same vein, what would it harm if someone were to put a bead of structural adhesive between it and the skin? That is what was originally there to begin with. I posed the question to Piper and the tech said that he isn't an engineer and to fill out a damage report and they'd get back with me.

We really need a smiley blowing his brains out but I guess these will have to do. :mad2: :incazzato:
 
Timbeck2 said:
Nothing except what one guy said earlier (on page 1) about strengthening one part may weaken another would cause concern. In the same vein, what would it harm if someone were to put a bead of structural adhesive between it and the skin? That is what was originally there to begin with. I posed the question to Piper and the tech said that he isn't an engineer and to fill out a damage report and they'd get back with me.

We really need a smiley blowing his brains out but I guess these will have to do. :mad2: :incazzato:
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IF ---- IF I were your A&P-IA I'd simply pull the two rivets that hold the stiffener in, then run a tyco wheel on both parts get them clean, re-Alodine the bear metal, and run a bead of epoxy structural adhesive on both, and replace while wet. with 2 rivets in the same holes.
 
I wish you were because that's exactly what I want to do. Thanks for the link. I will do that.
 
Timbeck2 said:
I wish you were because that's exactly what I want to do. Thanks for the link. I will do that.
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I charge 350 per day, plus expenses, want me to come down? Have motorhome will travel, I need a road trip. :)
 
Tom-D said:
IF ---- IF I were your A&P-IA I'd simply pull the two rivets that hold the stiffener in, then run a tyco wheel on both parts get them clean, re-Alodine the bear metal, and run a bead of epoxy structural adhesive on both, and replace while wet. with 2 rivets in the same holes.
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That's the most sensible suggestion I have seen so far. :thumbsup:
 
Tom-D said:
I charge 350 per day, plus expenses, want me to come down? Have motorhome will travel, I need a road trip. :)
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I didn't name you but passed your suggestion on to my A&P. He works cheaper than you do. ;)
 
Timbeck2 said:
Quoted myself <giggle> what a nerd. :rolleyes:

Now I'm thinking the tech rep has the wrong drawing because two more Cherokee owners have sent me pictures of their airplanes with the stiffeners in place. So it is factory. Another thing, there is some sort of fabric under these things as well. I may have "discovered" something that was normal all along but my A&P doesn't think so. Still waiting on words from Piper.
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Old Boeing's had/have a fabric in the cold bonded structure.
 
Timbeck2 said:
Nothing except what one guy said earlier (on page 1) about strengthening one part may weaken another would cause concern.
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Maybe we should ask him to explain the physics of that one...

It's been a long time since I did any structural work but never heard anything about strengthening one thing actually weakening another. The strength of a structural member depends on material and dimensions. Gotta change one of those items to weaken it.

Perhaps what the guy meant was strengthening one part may change where a structure fails. Dunno.
 
www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA301660
3-1 Compressive Strength of Sandwich Panels, 112 Cloth ...... completed by adhesive bonded and mechanically fastened joints. One of these .... Development of the Piper Aircraft plastic plane began in 1958. ...... by a light weave scrim cloth.

May be something of interest there. I didn't download it. I'm not at home.
 
Another possibility:
https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19840003150.pdf
of Composite Structural. Elements for General Aviation. Aircraft. Applications ...... of woven- fabric reinforced advanced composites for comparison with the results ..... bonded composite joints .... to lay up scrim reinforcement ..... Piper Aircraft.
 
Clark1961 said:
Maybe we should ask him to explain the physics of that one...

It's been a long time since I did any structural work but never heard anything about strengthening one thing actually weakening another. The strength of a structural member depends on material and dimensions. Gotta change one of those items to weaken it.

Perhaps what the guy meant was strengthening one part may change where a structure fails. Dunno.
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that is exactly it. when designing aircraft structures, the structure is designed to carry loads in a certain way. by adding stiffness where it was not originally designed, you change those load paths. that may impart loads in other areas of the structure that were never intended to carry the load. in this case I doubt that it would, but without doing the load calculations you cannot be sure. it the same reason you cannot just go adding inspection panels in any skin you want to without doing the engineering work for it.

bob
 
Timbeck2 said:
For what purpose?
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It's there to hold the glue in place until it sets up. plus it will prevent the two parts from squeezing the glue totally out of the bond area.
 
Tom-D said:
It's there to hold the glue in place until it sets up. plus it will prevent the two parts from squeezing the glue totally out of the bond area.
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It's actually there because it's a cold bond process. The cloth holds the epoxy resin in a uncured state in icebox until assembly.
 
GlennAB1 said:
It's actually there because it's a cold bond process. The cloth holds the epoxy resin in a uncured state in icebox until assembly.
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It's there for the same reason we place a woven mat in any wood epoxy glue seam.

Most structural adhesives don't use it, Grumman simply etched the bond seam, smeared the glue on assembled the sheets and allowed it to cure.
same can be done here.
 
GlennAB1 said:
It's actually there because it's a cold bond process. The cloth holds the epoxy resin in a uncured state in icebox until assembly.
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To note the cold bond process is simply a way to control glue mixture and speed up the assembly process. That way the manufacturer will not have some duffus on the factory floor mixing the resins, and hoping the glue will kick. the mixing is done in the laboratory under controlled environments.
 
bnt83 said:
Oven cured / bonded structures and even composite assemblies themselves are repaired using adhesives without an oven every day.
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Some can be. Due to the age of this Piper, I doubt it was hot bonded, but I bet it was vacuum bagged, thou, and will require that for repair.
 
Tom-D said:
To note the cold bond process is simply a way to control glue mixture and speed up the assembly process. That way the manufacturer will not have some duffus on the factory floor mixing the resins, and hoping the glue will kick. the mixing is done in the laboratory under controlled environments.
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It's definitely to speed up assembly, but it' was stored at dry ice temperatures to enable installation before curing begins.
 
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Tom is correct. Beechcraft has stopped using scrim cloth as Hysol 9309.NA has micro balloons in it, which apparently serves the same function.
 
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