Fatigue analysis of a P180 aircraft main landing gear wheel flange

A piece of inner wheel flange separated from the main landing gear (MLG) right wheel of a Piaggio Avant P180 aircraft during taxing on the runway. The wheel was a 2014-T6 aluminium alloy and had been in service 22 years. Morphological observation of the fractured surfaces indicated fatigue was the cause of failure. The crack grew to approximately 8 cm in length and 5 cm in deep before the final catastrophic failure and was due to a corrosion pitting promoted by fretting from the tyre bead and the tube well, thus causing the removal of the protective coating. The fatigue life assessment also provided an estimation of the number of flight cycles to failure supported by the wheel during the crack propagation confirming those accumulated since its last inspection. It was recommended the inspection interval be reduced one-third of its original one as well as a proper maintenance procedure to be introduced in order to verify the integrity of the coating, to remove eventually corrosion and re-protect the component.