There were at least two Stearman accidents - one during practice near Rockford Illinois (Rolly Cole 1963), and one at Valparaiso Indiana (Bill Adams 1966?) which involved the R-985 crankshaft breaking, allowing the prop to tear off most of the wing structure on one side.
In the latter case, and probably the former too, a triple snap roll was performed - brutal on man and machine. The poor P&W engineers must have never envisioned such gyro loads on their hardware.