these photo's are of the blade off a raven 2 in new zealand. about 910 hours in service.
the chalk hatched lines show the extent of the delamination under the doubler.
flimflam, the robbie head may look like it is underslung but it does not have the ability to rock like a true underslung head that has a gymbal and a yoke.
the gymbal allows the head to flap and the yoke, attached to the gymbal by pillow blocks, allows the blades to rock, relieving all of the hunting stresses on the grips. an effective design feature for two bladed systems.
the robbie head does not have this feature.
to me it looks like the lead and lag, (hunting), stresses are still taken up by the blades and maybe the root cause of the problem.