[Public-list] Bronze turnbuckles - Inspection

[Michael Connolly]

Dan,Steven, Gordon and others,
This is something that has bothered me for a while.   
 
My boat surveyor just said "Replace those old bronze turnbuckles, they aren't any good".
 
Now, being a sailor and not wanting to dispose of anything still useful I am reluctant to refit just to please the surveyor or perhaps the insurance company.  
 
My preconception is that the Alberg 30 rig is designed plenty stout enough with a more than an ordinary margin of safety.  My turnbuckles are corrosion free and turn freely.
 
Is there some inspection that I can do to assure myself that they are fine to keep using on the boat?   If I take them apart and inspect for galling /damaged threads and find them free of these defects are they good to go?  If the bodies have no visible cracks are they likely to fail unexpectedly?
 
I know of the 'Zyglo' process for aluminum and the 'Magnaflux' process for ferrous metals. Is there something to use for copper alloys to detect surface fractures that can not be seen with the naked eye?
 
I have a couple of older boats with all bronze hardware and would like retain that look and be safe at the same time.  All comments welcome.
 
I am glad that Dan Sternglass brought up this issue, and happy for him that the failure was at the most convenient of times.
 
Michael Connolly
Alberg #133 Lorrie Rose
Seafarer #154 Tammy Norie