i think that the examples of "flapping" you gave are not realy flapping but teetering. the only way the flapping hinges move is by changing the load on the disc either with weight or high 'g' movements.
for example when flap back occures the head tilts back with the disc, not just the blade swiping past the nose.
are you sure that the elipticle holes arent just wear caused by coning under power? this would let the blades lag a bit behind their original line.
what do you recon?
