An ATSB investigation has found that fatigue cracking in an XPT axle led to a minor derailment of an XPT passenger service from Melbourne to Sydney on 9 February 2006 at Harden.

The Australian Transport Safety Bureau investigation into the derailment concluded that train ST22 derailed as a result of the axle completely fracturing and eventually derailing one wheel.

Subsequent examinations by RailCorp, the train operator, led to the discovery of thirteen other XPT power car axles with surface defects, or cracks initiated by surface defects, in highly stressed areas.

The ATSBs examination of five of the axles revealed a crystalline material, consistent with track ballast, embedded in each fatigue crack at its origin. It was probable that impacts from track ballast from unknown location(s) had led to the formation of the cracks in the axles.

The investigation also found that routine testing of the axles carried out by the operators maintenance contractor was ineffective and resulted in the fatigue cracks going undetected for a considerable period of time.

Both RailCorp and the New South Wales rail regulator have initiated safety actions to reduce the risk of fatigue cracks leading to similar axle failures.

The ATSB has issued a safety advisory notice to all rail vehicle operators in Australia to consider their maintenance and inspection regimes to detect possible fatigue cracks.

Copies of the report can be downloaded from the ATSBs internet site www.atsb.gov.au

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