While there was no documented evidence of such, Pacific National advised that they actively manage the risk of looseness and fretting damage to bearing components, but since mid-2007 have not relied solely on fault indications identified by RailBAM.
Their approach is to consider RailBAM readings in conjunction with wheel impact detection and other bogie faults such as steering issues and only remove bearings if there is no other explanation for the readings. In addition, Pacific National advised that they are committed to developing a composite alarm application where trends may be better analysed individually and compared to bearing faults, wheel impacts and bogie faults such as steering issues.
Considering the maintenance processes currently in place, it is recognised that bearing failure due to looseness and fretting is relatively rare. Since abandoning the process of routinely removing bearings that have shown looseness or fretting indications (RailBAM), Pacific National advised they had not observed any increase in the number of faulty bearings exhibiting looseness and fretting issues.
However, without documented records, this observation cannot be effectively monitored. Considering the potential consequence of a screwed journal derailment, a review and documentation of processes for managing bearing failure due to looseness or fretting may be warranted.