Lu,
I don't know where you get your sideslip certification 'facts" from but you are way off base.
No helicopter I know of except Comanche is capable of what you think every helicopter must do ("To gain certification a helicopter must be flown in a 90-degree sideslip at .68 VNE both left and right and, it must be flown 10-degrees out of trim at the same speed yet the FAA has placed a “restriction” on these maneuvers.")
Also, the idea of "grandfathering" is not a new one to ppruners, please don't single out the Robbie as the lone participant.
Regarding sideslip sensitivity, the entire semi-rigid rotor fleet, including all Hueys is susceptable to the excessive flapping/mast bumping problem that you describe.
Regarding rigging, you are a broken record, and you are so far off base on the delta three rigging procedures it isn't worth wasting electrons posting a rebuttal. The Comanche rigging had VARIABLE swashplate tilt phase angle (gamma) as a function of SPEED, Lu. That is how little you know about helicopter aerodynamics. If you stuck to what you know, your contributions would be so very strong. However, when you yet again climb on your soapbox, it is almost embarassing.
The problem with that Robbie that was the subject of this thread until you hijacked it - the trailing edge crack - is possibly due to the excessive stiffness in the rotor head as described in the initial reports. This stress rise might be a strong contributor to blade forces and thus a stressor that can help cause a crack. The semi-useless speculation cannot help the stuation, especially when it goes so very far afield. The quality of the investigations in Britain is very high, let's see what the facts are, shall we?