Boeing 767-238, VH-EAQ
The left engine of a Boeing 767-238 aircraft (VH-EAQ) failed
during the climb phase of a regular passenger transport flight from
Melbourne to Sydney. After the failure, which was characterised by
a single loud 'bang' and severe vibration, the engine was shut down
and the aircraft returned to Melbourne.
Engineering inspections of the JT9D-7R4 engine found that one of
the fan blades had failed part-way along its length and impacted
the fan case at the 11 o'clock position, causing the failure of
several nose-cowl bolts and substantial damage to components
adjacent to the impact point. After the initial impact, the failed
blade struck the inside of the nose cowl, forward of the fan. This
impact was of sufficient energy to puncture the nose cowl and allow
the escape of the blade segment. No damage was caused externally to
the airframe or control surfaces.
ATSB laboratory examination of the blade section remaining
within the fan rotor disk found that the blade had fractured as a
result of fatigue crack growth from a pre-existing defect at the
blade trailing edge. The defect was identified as a shallow crack
that had formed during or before the last blade refurbishment
operation, carried out in 1991. Non-destructive examination
procedures carried out on the blade following the refurbishment had
failed to detect the defect.
In 1998, the manufacturer purchased the engine for use as a
lease unit. The defective blade was installed into the engine
shortly thereafter. At the time of failure, the blade had operated
for 7,187 hours and through 2,083 cycles following its 1991
refurbishment. Operating times and cycles before the blade
refurbishment were not available.