[ARC5] Fw: Screw failure

[J. Forster]

> Screw heads might fail due to thermal cycling and fatigue.

> Just what I was thinking.

I checked and aluminum is about 23 and brass about 20 ppm/deg C. This is not a
lot of difference and is therefore less likely to cause fatigue since the cyclic
stress is low.

> And the over zealous depot tech probably helped too.

IMO, that's the most likely cause.

>  Stainless steel would have been a better choise? Don't know.

It's difficult to tell. I read somewhere that brass deteriorates over time.
That'll require more research tomorrow.

>  Weight a factor? I don't think so.Cost a factor?Maybe.

Doubt it on both.

Material availability?Probably.Could be

Possible.

> The base metal,brass, is sort of a "pot" metal and can probably have a wide
> range of ingredients and still be brass.

> There are many alloys. Heat treatment may also change the properties.

>  And,like bullets,if used even only once,it did its job.

Not the same here.  The radios were built to last, since failure could kill
people and worse.

>  We all think we are nuts 'cause we like the radios,but what about the guys
> who collect the whole airplane? Or tank?
>  I would die for a PT boat myself!

People collect all kinds of strange stuff. No accounting for taste.

>            Jay
>