TWO “fatigued and fractured” bolts in a Pacific National freight train caused a locomotive fire at Cardiff that left emergency crews unable to respond for at least an hour because of live overhead power lines.
The 19mm diameter bolts securing an oil filter tank failed about 5am on April 4, 2016, causing the locomotive to catch fire shortly before entering Cardiff railway station, an Australian Transport Safety Bureau investigation report released on Thursday found.
Pacific National has halved its bolt replacement regime from two years to one after the bureau found two of 10 oil filter tank cover bolts failed because of fatigue and overload fractures linked to incorrect tensioning.
The resulting fire, which the two train crew could not contain, forced the driver to stop the train 250 metres north of the station only minutes before crew evacuated, and an engine exploded, while NSW Fire and Rescue called for power lines to be isolated.
The fire stopped a passenger train from passing the burning locomotive and passengers were forced to leave the train for alternative transport.
Overhead wiring was not isolated until 6.35am. More than three hours after the fire was first reported, it was finally extinguished.
An investigation found the fire ignited when the failed bolts loosened the oil filter tank cover, allowing high pressure oil to escape and come in contact with hot engine components.
The tank, which is part of the engine’s lubricating oil system, normally contains 1500 litres of oil. There was about 800 litres of oil in the system after the incident.
In response to the incident Pacific National said it developed a bolt tightening and removal procedure; reduced bolt replacement frequency to 12 months and retrofitted a guard in the relevant locomotives to minimise the risk of oil escaping from the filter tank and coming into contact with hot engine components.
A bureau report said correct tensioning of bolts could be “a critical aspect of ensuring equipment functions as designed”.
“Operators should ensure their safety management systems provide appropriate procedures for bolt inspection and tensioning where there is a risk of equipment failure, especially when the consequence can escalate to fire,” the bureau said.