I may be able to help
Hi CZH
I am an expert in adhesive bond failure forensics. I may be able to help. Most rotor blades are adhesively bonded, and if the failure is caused of related to the bonding process maybe I can help.
Firstly, do you have any close-up photos of the blade? Secondly, how is the blade constructed? Is it spar with thin skins and honeycomb core? Next, where were the cracks in the other blades located? Did this blade crack in the same location? What materials were used to make the blade?
Regards
Max
Boys thanks for fantastic support!! Since more people replied with same problem, we have created gallery on Flickr. As you can see the problem is known at least since year 2006 !! Looking close to pictures, there is no spar inside and no honeycomb core. Just and just the thin skins....
Flickr: czheliman's Photostream