Fatigue life analyses were performed using a standard strain-life approach and a linear cumulative damage parameter to assess the effect of a single accidental overload on the fatigue life of the Haynes 230 nickel-base superalloy X-43A rudder spindle. Because of a limited amount of information available about the Haynes 230 material, a series of tests were conducted to replicate the overload and in-service conditions for the spindle and corroborate the analysis. Both the analytical and experimental results suggest that the spindle will survive the anticipated flight loads. Glaessgen, Edward H. and Dawicke, David S. and Johnston, William M. and James, Mark A. and Simonsen, Micah and Mason, Brian H. Langley Research Center NASA/TM-2005-213525, L-19082 WU 23-064-50-10 38412 FATIGUE LIFE; SPINDLES; X-43 VEHICLE; RUDDERS; AERODYNAMIC LOADS; HEAT RESISTANT ALLOYS; NICKEL ALLOYS; CRACKS; FINITE ELEMENT METHOD; STRESS-STRAIN DIAGRAMS; TORQUE; CRACK OPENING DISPLACEMENT; CUMULATIVE DAMAGE