Fatigue fracture of an AMX aircraft main wheel

A forged 2014-T6 aluminium alloy main wheel of an AMX aircraft failed during pre-flight taxiing. e occurred on the wheel housing hub and its origin was located on the interior edge of the bearing cup housing. The wheel experienced high cycles fatigue. A plastic deformation was produced during the wheel mounting operations caused an abnormal stress concentration. It has been identified as cause of a progressive fracture mechanism. Consistent optical, metallographic and electron microscopy evidences were collected. Moreover, Finite Element Analysis (FEA) demonstrated that the observed defects produced the stress level needed to fatigue to initiate. Recommendations were issued in order to improve the Non-Destructive Techniques (NDT) used to monitor the wheel structural integrity. Laboratory tests showed that ultrasounds in this case would be far more efficient than the prescribed eddy currents.