The role of NDI on the failure analysis of an aircraft propeller hub

Abstract

This paper analyses the causes of an incident in an aircraft propeller hub. The aluminum alloy propeller blade hub was detached from the plane bearing one of its two blades with the other one being jettisoned away. Stereoscopic examination of the fractured hub revealed that it was initially cracked by fatigue, with the crack initiating on the root of the third and fourth spirals and propagating form the inner to the outer. SEM analysis showed that the crack epicentres were created very close or/and on the spiral roots and were attributed to microcracks from corrosion pits and high stress concentration. Non Destructive Inspection was both used on the other side of the hub and the remaining three hubs of the plane and confirmed the presence of cracks similar to those which caused the fatigue failure of the fractured hub but at earliest stage of development.