A fatigue crack in a coal train wagon bogie went undetected during preventative maintenance before it escalated to a full fracture, increasing the risk of derailment, an ATSB investigation has highlighted.
On 12 December 2017 Pacific National coal train TM78A was undergoing a roll-by inspection at Kooragang Coal Terminal in Kooragang, New South Wales, when a maintenance worker identified a fracture on the lead bogie of the train’s 35th wagon. The train was stopped and the wagon was removed for inspection.
An investigation into the cracking, conducted on behalf of the ATSB by NSW’s Office of Transport Safety Investigation (OTSI), found that the fatigue crack had gone undetected during earlier preventative maintenance, and that it was probable that the fracture was visible the day before during unloading of the wagon, but had gone undetected.
Identifying this fracture in time likely prevented a derailment.
The NDCA bogie frame design has a history of fatigue cracking, which increases the risk of derailment if the cracking is not identified. Pacific National had processes in place to identify fatigue cracking, but this crack was likely not detected due to the location of the defect on the bogie frame.
OTSI COO and Deputy Chief Investigator Kevin Kitchen said the incident highlights how asset managers should ensure that inspection techniques effectively monitor and report on the condition of assets.
“Risk controls should also be continuously assessed to control risk to an acceptable level through the life cycle of an asset,” Mr Kitchen said.
In response to the incident, Pacific National has made changes to the maintenance standard used during scheduled maintenance, increasing the area of the bogie frame subjected to non-destructive testing. This change is aimed at identifying and addressing fatigue cracking prior to any escalation of defects.
“Identifying this fracture in time likely prevented a derailment,” Mr Kitchen said. “However, if the worker who identified the defect had been positioned on the opposite side of the train, it could have been missed.”
Read the report: Fractured bogie frame on coal train TM78A, at Kooragang, New South Wales, on 12 December 2017