At 10.45pm on June 5, the crew of Pacific National coal service ER 64 travelling between Fassifern and Awaba on the Sydney Trains network reported that the fourth locomotive in the train, 8221, was on fire.
The crew also requested assistance from a local fire brigade to help extinguish the flames.
The fire brigade arrived onsite at 11.45pm, with the fire extinguished at 1.39am on June 6.
The locomotive suffered significant damage and was stowed in a siding at Awaba before the train continued to Eraring.
The locomotive was subsequently recovered to maintenance facilities at Cardiff, Newcastle, pending examination and assessment.
The probe is being run by the Australian Transport Safety Bureau and the Office of Transport Safety Investigations.
“The ATSB has commenced an investigation into this incident,” it said in its report.
“The Office of Transport Safety Investigations (NSW) will lead the investigation under the provisions of the Transport Safety Investigation Act 2003, with assistance provided by the ATSB where necessary.
“Investigators have commenced collecting evidence and statements from involved parties, which will be analysed and a draft investigation report compiled.”