On Aug 26, 1:42 pm, Fred the Red Shirt
wrote:
On Aug 26, 1:35 am, Fred the Red Shirt
wrote:

...

Using bushings in a hole drilled in wood helps to reduce
that elongation by spreading that bearing stress over
a larger area in the wood, and is a lighter approach than
simply using a larger bolt. But it is still not a substitute
for maintaining the proper tension in the bolts.

I hasten to correct this. It is right if the bushing is merely
pressed into the hole. If the bushing is well-bonded to the
wood then it will distribute the stress better.

--

FF

Excellent question! The plane I built called for 2024-T4 aluminum
bushings to be epoxied in the cap. As I pointed out, using this
approach not only has a larger bearing area against the wood, which is
the weakest material in the load path, but it actually restores much
if not all of the strength that was lost when the hole was drilled in
the spar cap. If you have gone to the trouble of using bushings,
epoxying them in place is fairly simple and cheap as hell. Adds very
little work.

Regards,
Bud