Failure analysis of nose wheel hub of an aircraft

A rejected nose wheel hub with loose race at the bearing housing area was sent to this laboratory for investigation. Based on the signatures on the axle, and the outer and inner surfaces of the bearing, it appeared that the looseness of the race was due to inadequate fitment of the bearing at the bearing seating area of the wheel hub. There were no evidences to suggest that there was excessive axial load on the bearing in the outward direction which could lead to detachment/looseness of the bearing race. It is, therefore, stated that this failure is not similar to the one that was investigated in this laboratory earlier (refer NAL Report No. MT-FA-1205-05-2010 dated May 14, 2010). In the earlier case, the dislodgement of the bearing was by fracturing of the outer race due to excessive axial load in the outward direction. Hence, these two failures need to be treated differently