A 2-stage centrifugal flow turboprop Dart engine failed recently in service due to the failure of the low pressure impeller. Examination by various techniques including electron microscopy based on scanning, energy dispersive analysis of x-ray and transmission electron fractography indicates that the cause was metallurgical in nature, resulting from a material manufacturing defect followed by fatigue fracture and finally by tensile rupture of the material.
Investigation Into the Cause of Failure of a Turboprop Impeller in Service