It is apparent that the issues raised in these documents must have been addressed. The subject aircraft was issued a special airworthiness certificate as experimental/research this past January. This info is readily available from the FAA registry. The FAA will usually not issue an experimental airworthiness certificate for an old, normally certificated aircraft unless there is good reason. Who knows what that justification was but it may have been as simple as using the aircraft as a test bed for new tail or main rotor blade designs before they are certificated. One also has to assume these folks were familiar with the aircraft , its history and current condition. I hope they figure out what happened.