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"jls" <jls1016@bellsouth.net> wrote in message
news:1165619525.716725.124400@j44g2000cwa.googlegroups.com...
>
> veeduber@isp.com wrote:
> [...]
>> Once the early designers appreciated the advantage of the one over the
>> other they moved immediately to true monocoque structures of molded
>> plywood, welded steel tubing and so forth, but the structural integrity
>> of the 'box' structures combined with their simplicity of fabrication
>> makes the method ideal for homebuilders even today.
>>
>> -R.S.Hoover
>
> Which reminds me. A little googling will bring up an Avions Mudry Cap
> 10B (also known as Apex), the left spar of which failed in Texas a few
> years ago (c. 2001), killing the pilot. The problem was compression
> fractures in the upper box spar cap and some other damage which could
> not be (or was not) inspected and repaired, even after compliance with
> several service bulletins requiring inspection and repair near the wing
> attach fittings at the wing roots. According to the NTSB report, none
> of the glue bonds failed; the failures were compression cracks in the
> Sitka spruce and other woods in the main spar. Having read the reports
> and seen the extensive photos of the failures, I think if I had a Cap
> 10, 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
