OOW, I know nothing of Enstroms, but about the blade delamination -
All metal blades that I know of are laminated. Solid metal blades would be far too heavy and far too expensive to mill. Rotor blades have a metal spar at or near the leading edge, with a honeycomb of some sort behind that, tapering to the trailing edge. The metal skin is laminated to the honeycomb, and to itself at the trailing edge. If the bond separates, the strength of the entire structure is compromised. The usual way to detect this delamination is, as mentioned, tapping the skin with a coin. Be careful, though. I've seen blades that could be dented with my knuckle, and taps with a plastic screwdriver handle or similar completely ruined them. If the delamination is severe enough, you may be able to see it visually, by looking along the blade at a very low angle, and seeing a slight bubble. If you can see it, the blade is likely worthless.