fatigue failure of the propeller hub, which resulted in separation of the propeller assembly and reduction of aircraft control. Also causal was: the resultant lack of compliance with Airworthiness Directive (AD) 89-26-08, due to ambiguous and unclear wording of the AD as issued by the FAA. Factors relating to the accident were: non-compliance with McCauley Service Bulletin 179A and McCauley Service Letter 1989-5, and an encounter with soft terrain during the aborted takeoff.