Although recent Airworthiness Directives and Service Bulletins have addressed problems with crankshafts in Lycoming engines, none of them applied to this particular airplane, Lycoming spokeswoman Daria Fish told AVweb yesterday. "Whether the fracture of the crankshaft at that location was secondary to some other cause is not known yet," Fish said. Further, "the reported fracture here does not involve the portion of the crankshaft which was the subject of prior incidents." Fish said the information she has received so far indicates that after the initial reports of rough running, the airplane was checked by a mechanic and flown again, and continued to run rough. "We are advised that a decision was then made to ferry the plane to a service facility and the incident occurred shortly after takeoff," she said. Lycoming is assisting the NTSB in the investigation.