9A
Interesting tools could\should show the tail section disbonds, when they have reached a level that is measurable.
How quick is the de lamination\ failure once it starts ?
So far the tails have been on ground, & the HK is suspected blade failure, it would appear that there are numerous others reported here (that cannot be all not every user is a PPRUNER)
If as BM is saying these could be due to micro bubbles, the way I read the literature, it does not go down to the level that is starting these problems.
It would appear that manufacturers are using either flawed calculations, poor \ incorrect procedures, or the material is not stable enough for the job.