Boeing Co 767-277, VH-RMG, Melbourne, Aero. Vic. 4 November 1999

During the take-off roll, the crew of the Boeing 767 heard a
loud bang sound so they immediately discontinued the takeoff. A
runway inspection by the airport safety officer and fire crews
found fuel and engine components on the runway. The aircraft was
towed to the company maintenance facility and the runway was
reopened after approximately 30 minutes.

Maintenance inspection found metal particles in the tailpipe of
the engine. An engine change was carried out and the aircraft was
returned to service.

Disassembly of the removed engine found that a blade in the
second stage high-pressure turbine (HPT) had failed. The liberated
blade then caused catastrophic secondary damage to components
downstream during its passage through the engine. The
manufacturer's design features for failure containment prevented
damage to the aircraft or other systems by trapping high-velocity
debris within the engine. Some low-velocity debris was ejected from
the tailpipe.

The remaining segment of the blade firtree root in the HPT disc
was retrieved and examined. The examination revealed the presence
of a casting defect in a cooling-air channel web of the firtree
root. This led to initiation of fatigue crack growth and eventual
fracture of the turbine blade. Fatigue crack initiation was
associated with a discontinuity created during casting. It was
evident that the fatigue crack did not intersect the outer surface
of the blade prior to failure.

After completion of the examination, the blade was returned to
the engine manufacturer who has been requested to furnish a report
on the metallographic sectioning examination of this component.