Simulated turbine blades were subjected to transient and steady-state heating and spanwise loading in a Mach 1 burner rig. Leading-edge cracks were produced which were similar to thermal-fatigue cracks observed during engine service. Crack initiation and propagation data were obtained for a variety of test conditions.The simulated turbine blades consisted of coated and uncoated IN 100 and B 1900 cambered airfoils with grips for application of spanwise load to simulate centrifugal stress. Test variables were blade temperature, spanwise load, and steady-state (hold) time. The Mach 1 gas velocity substantially reduced conventional creep rupture life. This caused a substantial reduction in thermal fatigue life. Coating effectiveness was below that for low velocity tests.