Failure investigation of wheel gear hub assembly of an aircraft

The failure investigation of an aircraft rear wheel gear hub at hood position was conducted to find the cause of fracture. The stereographs represented river pattern at crack initiation site originating from the preexisting cracks at the inner surface of hood. The metallurgical study showed the overaging of wheel hub material. Stress analysis by finite elemental analysis identified the stress concentration regions nearly at the same positions of wheel hub from where it was failed in reality. The SEM analysis of fracture surface represented that crack propagated by cleavage mode with microvoid coalescence at the eutectic and α-Mg interface. The overloading was a cause of final failure with visible features of chevron marks pointing back in the direction of crack originating site.

► River pattern originated from the preexisting cracks at the wheel hood caused failure.
► In eutectic phase β-Mg17Al12 was germinated within α-Mg grains confirmed over aging.
► The Finite Element Analysis identified regions of high stress concentration.
► The SEM images showed cleavage and intergranular failure caused by overloading.