Preliminary report
Preliminary report released 9 October 2011
This preliminary report details factual information established in the investigation’s early evidence collection phase and has been prepared to provide timely information to the industry and public. Preliminary reports contain no analysis or findings, which will be detailed in the investigation’s final report. The information contained in this preliminary report is released in accordance with section 25 of the Transport Safety Investigation Act 2003.
Abstract
At about 0145 on Saturday 28 May 2011, intermodal freight train 5MP9 was travelling from Melbourne to Perth when it experienced a catastrophic failure of a locomotive wheel at about the 849.700track kilometre mark near Fisher, South Australia. There were no injuries. The locomotive did not derail but separated wheel fragments damaged the locomotive traction motor and associated components. The single-line track incurred four rail breaks and broken sleepers over a distance of about 1 km.
Final report
Safety summary
What happened
On Saturday 28 May 2011, intermodal freight train 5MP9 was travelling from Melbourne to Perth when one of its locomotives (SCT class) experienced a catastrophic wheel failure near Fisher, South Australia. The locomotive did not derail but sections of the broken wheel damaged a traction motor and associated components. The train travelled about 1976 m after the wheel failed and caused some sleeper damage and four breaks in the rail.
What the ATSB found
The investigation found that a fatigue crack had initiated at a small indentation on the inside of the wheel rim and then radiated towards the flange and tread regions before the wheel completely failed.
The rate of growth of the fatigue crack was influenced by high in-service mechanical loading of the wheel.
Inspection and measurement after the incident revealed that the locomotive wheel had sufficient rim, tread and flange thickness and was not worn beyond its service life, however it was likely the crack was present at a previous visual inspection and was not detected.
What’s been done as a result
The locomotive owner and maintenance provider has advised that they have implemented a revised program for more regular wheel re-profiling of its SCT class locomotive wheels to remove surface stressors in the wheel rim.
The locomotive maintenance program has also been enhanced to include a focus on visual inspections to detect impact damage to wheels and scheduled ultrasonic testing of locomotive wheels after mid-life is carried out when they are machined to detect cracks that may not be visible to the naked eye.
Safety message
Operators of locomotives that are exposed to high in-service mechanical loadings should be aware of the potential for wheel failure due to fatigue cracking and ensure inspection and maintenance programs include techniques for detecting and assessing wheel defects with the potential to lead to fatigue cracks.
Occurrence summary
| Investigation number | RO-2011-009 |
|---|---|
| Occurrence date | 28/05/2011 |
| Location | near Fisher |
| State | South Australia |
| Report release date | 03/07/2013 |
| Report status | Final |
| Investigation level | Systemic |
| Investigation type | Occurrence Investigation |
| Investigation status | Completed |
| Mode of transport | Rail |
| Rail occurrence category | Rolling Stock Irregularity |
| Occurrence class | Incident |
| Highest injury level | None |
Train details
| Train number | 5MP9 |
|---|---|
| Type of operation | Freight train |
| Departure point | Melbourne, Vic. |
| Destination | Perth, WA |
| Train damage | Minor |