TET
Tet
There may be an element of stress concentration at the curve in the back of the blade, and it is possible that a nick in the metal led to cracking. However, there may also be underlying issues.
I have a good friend in NZ who is a qualified crash investigator and he is a specialist in failure forensics. His company is Prosolve. He and I worked together on the crash of DQ-IHE which was most probably as a result of blade break-up in flight. I did the adhesive bonding failure forensics issues and he did the rest.
I think we both would like to get access to this blade.
I'll send you a PM.
Blakmax