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[Ric Gillespie]

How many times have I heard in the back of a hangar, "Bend to match. Beat to fit."

[JNev]

LOL!!!

What a "BFH" (Big Freakin' Hammer) is for...

[Tim Collins]

...
What you observe (and that's a good catch) could be consistent with that - a bit of residual bulging, etc. where the major curve was met, the the fore-and-aft curvature had little place 'to go'.  That could also be all the more reason why so many stiffeners may have been installed - to reduce buckling tendencies or more likely oil canning from such an installation.

Thank you.  I can only wonder how does that bulge jive with the rivet patterns, both on the artifact and forensically seen in the pictures? One would think that underlying stringers would create more longitudinally linear patterns mitigating any such bulge. The stringers wouldn't have been that far apart.

[Ric Gillespie]

Here's a closer picture taken in Darwin.  Is there a bulge?

[Jay Burkett]

The old-timers I started to work with always said it was: "Beat to fit.  Paint to match."  (They were, of course, referring to the standard workmanship note included on any repair order or work instruction.)

Ric,

You may know:  Are those openable bays and removeable panels "standard" on the Electra?

[Tim Collins]

Here's a closer picture taken in Darwin.  Is there a bulge?

Not that I can see in that picture, but it sure can be seen in this picture:
http://e-archives.lib.purdue.edu/cdm4/item_viewer.php?CISOROOT=/earhart&CISOPTR=284

[JNev]

...
What you observe (and that's a good catch) could be consistent with that - a bit of residual bulging, etc. where the major curve was met, the the fore-and-aft curvature had little place 'to go'.  That could also be all the more reason why so many stiffeners may have been installed - to reduce buckling tendencies or more likely oil canning from such an installation.

Thank you.  I can only wonder how does that bulge jive with the rivet patterns, both on the artifact and forensically seen in the pictures? One would think that underlying stringers would create more longitudinally linear patterns mitigating any such bulge. The stringers wouldn't have been that far apart.

First, as to 'that bulge', how real / prominent is it?  Granted there well may be such a feature, but is is visually exaggerated by the light perhaps?  See Ric's post above.

Second, if it is considerable - the stiffeners might brace that well, good point.  Or they might not.  Depends on how beefy they were and how they may have been conformed to the skin when shot in.  They may have been shot in as an afterthought.  The surviving rivet suggests an aggregate stack-up of .060 according to the NTSB report on 2-2-V-1.  That is, where that rivet was - and we don't know that all the stiffeners (or whatever was behind this piece) was that thick, others might have been lighter.

.060, if so, is fairly substantial, but again - how big is the 'bulge', truly (not so evident to me, seems to depend on photo angle / light), and how were the underlying pieces laid in?  We don't really know.  I tend to think the bulge may not have been so significant.  See downstring -

[JNev]

Here's a closer picture taken in Darwin.  Is there a bulge?

Not that I can see in that picture, but it sure can be seen in this picture:
http://e-archives.lib.purdue.edu/cdm4/item_viewer.php?CISOROOT=/earhart&CISOPTR=284

That?  (What I've circled in attachment.)

I regard that as a minor pucker that is brought out by the oblique light - small stuff, easily existing even with stiffeners behind the panel.

[Tim Collins]

First, as to 'that bulge', how real / prominent is it?  Granted there well may be such a feature, but is is visually exaggerated by the light perhaps?  See Ric's post above.

Could be, I don't know. I doubt its merely superficial coloring - what would be the coincidence? worthy of a Hollywood effect's artist for sure. It certainly looks like a bulge in the skin to me

Second, if it is considerable - the stiffeners might brace that well, good point.  Or they might not.  Depends on how beefy they were and how they may have been conformed to the skin when shot in.  They may have been shot in as an afterthought.  The surviving rivet suggests an aggregate stack-up of .060 according to the NTSB report on 2-2-V-1. 

That's fairly substantial, but again - how big is the 'bulge', truly (not so evident to me, seems to depend on photo angle / light), and how were the underlying pieces laid in?  We don't really know.  I tend to think the bulge may not have been so significant.

But still, a bulge pulled into and riveted would show evidence of it wouldn't it? Maybe the added bracing wasn't done in Miami after all but post Darwin?  - arrived in Darwin and noticed patch done in Miami was bulging so added reenforcing stringers? Any evidence of work don on the skins post Miami? Just how strong is the rivet lines forensics for Miami pictures?  Don't know, just observing and guessing at scenarios. I see a bulge and would be interested to know how it fits in the scenerio for the patch. 

[Tim Collins]

That?  (What I've circled in attachment.)

I regard that as a minor pucker that is brought out by the oblique light - small stuff, easily existing even with stiffeners behind the panel.

You circled but a tree, step back and see the forest. Easily twice as wide as you circle and again taller, taking up much of the panel. A very broad and shallow U shape.

Gotta go, hopefully you can see what I'm talking about. will rejoin tomorrow.

t

[JNev]

First, as to 'that bulge', how real / prominent is it?  Granted there well may be such a feature, but is is visually exaggerated by the light perhaps?  See Ric's post above.

Could be, I don't know. I doubt its merely superficial coloring - what would be the coincidence? worthy of a Hollywood effect's artist for sure. It certainly looks like a bulge in the skin to me

Second, if it is considerable - the stiffeners might brace that well, good point.  Or they might not.  Depends on how beefy they were and how they may have been conformed to the skin when shot in.  They may have been shot in as an afterthought.  The surviving rivet suggests an aggregate stack-up of .060 according to the NTSB report on 2-2-V-1. 

That's fairly substantial, but again - how big is the 'bulge', truly (not so evident to me, seems to depend on photo angle / light), and how were the underlying pieces laid in?  We don't really know.  I tend to think the bulge may not have been so significant.

But still, a bulge pulled into and riveted would show evidence of it wouldn't it? Maybe the added bracing wasn't done in Miami after all but post Darwin?  - arrived in Darwin and noticed patch done in Miami was bulging so added reenforcing stringers? Any evidence of work don on the skins post Miami? Just how strong is the rivet lines forensics for Miami pictures?  Don't know, just observing and guessing at scenarios. I see a bulge and would be interested to know how it fits in the scenerio for the patch.

I've worked a lot of stubborn metal and it looks like a superficial 'pucker' to me - just enough 'hump' to create a minor shadow in oblique light.  I don't see it as being of any particular consequence to the supposition of skin and stringers installed in Miami, personally, just MHO of course.  YMMV, no sweat.

In fact, it may actually be the result of 'chasing' a distortation down to the smallest area possible trying to get a flat skin to conform - by the installation of stiffeners.  Seen that effect enough times to recognize it too.

Make your own judgment, of course.  That's mine, given my own experience.

[JNev]

That?  (What I've circled in attachment.)

I regard that as a minor pucker that is brought out by the oblique light - small stuff, easily existing even with stiffeners behind the panel.

You circled but a tree, step back and see the forest. Easily twice as wide as you circle and again taller, taking up much of the panel. A very broad and shallow U shape.

Gotta go, hopefully you can see what I'm talking about. will rejoin tomorrow.

t

Then please by all means circle what you are talking about (and don't imply selectivity on my part) - I don't see anything more than minor, expected variances for such a panel.  Much ado over nothing that I can see, Tim. 

[Jon Romig]

Thanks, Jeff for your detailed and thoughtful explanation (and refutation!).

1. I confused the exterior markings from the vertical frame 307 strut with the interior marks from the stringers. So my question is minimized, but still of some interest: how would the replacement member at frame 307 come to read on the exterior of the patch? I can imagine a makeshift frame member that did not fit the curve of the skin very well but was too strong to bend further once in place (and thus did not contact the skin much and could not be riveted), but some part of it bulged too far, distorting the skin enough to read on the exterior along a part of its length. The stringers could have been discontinuous and fastened in place after the 307 frame element.

2. Many of our scenarios for how the patch became detached bear upon how firmly the new stringers and strut at 307 were attached to the "original" airframe. If the motivation for the patch was to improve the rigidity of the airframe, we should expect these connections to be quite strong. How difficult would it have been, using just hand tools or even sheer muscle power (kicking?), to break these connections? It seems to me that one would have to both break these connections AND tear a hole in the .032 skin of the patch to create an escape route. Can one simply kick a hole in the skin of an Electra? Can you then kick the stringers out by breaking their connections to the rest of the frame?

[Nathan Leaf]

That?  (What I've circled in attachment.)

I regard that as a minor pucker that is brought out by the oblique light - small stuff, easily existing even with stiffeners behind the panel.

You circled but a tree, step back and see the forest. Easily twice as wide as you circle and again taller, taking up much of the panel. A very broad and shallow U shape.

Gotta go, hopefully you can see what I'm talking about. will rejoin tomorrow.

t

Then please by all means circle what you are talking about (and don't imply selectivity on my part) - I don't see anything more than minor, expected variances for such a panel.  Much ado over nothing that I can see, Tim.

I believe Tim is referring to this:

[Ric Gillespie]

It's either just the way the light is reflecting off the patch or it's a map of the 18th Congressional District in Kansas.