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I agree that metal structures can suffer compression related failures.
At my employer, a leading Regional Jet manufacturer, a situation came up
where landing gear legs were cracking due to localized stress during
hard landings, which were yielding a small zone of metal at the peak
stress point, within surrounding metal (300M steel) that did not quite
reach the compression yield point. As soon as the load was removed,
this set up a huge internal "force fight" between the yielded material
and unyielded material deep within the forging, leading to a cracked leg.
This requires the fitting to be capable of reaching a compression yield
limit before buckling, with just enough force applied to yield part of
the structure but not all of it. I think in the case of most metal wing
spars, the compression critical part of the structure will either
totally yield in compression or will buckle, leaving a bent wing.
Therefore, generally with metal wings after a wingtip strike, or
overstress in flight, the rule is if it ain't bent it's ok. With a wood
wing you have to somehow detect the compression failure within the wood
by inspection. This is the principal weakness of wood structures from a
practical operational standpoint.
John
Kyle Boatright wrote:
0, I'd rebuild the wings or ground it.
>
> Compression failures are due to either an over-stress condition, poor
> design, or poor materials. Compression failures have happened in every type
> of aircraft structure (metal, wood, and/or glass).
>
> Why would you ground your hypothetical CAP due to this one instance, which
> was probably caused by an overstress at some point (assuming no pertinant
> facts were omitted from this synopsis) ?
>
> Beyond that, if you rebuilt the wings, how would you know that the next
> person who flew it didn't overstress it on his/her first flight?
>
> KB
>
>
>
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Re: Glue it to it
