Qantas ATSB Report
ATSB delivers final report on Qantas 744 engine incident
Australian investigators have traced the cause of last November's Qantas Boeing 747-400 contained engine failure to the engine's high pressure compressor (HPC) blade, which had broken off at the root.
The aircraft, VH-OJD, had departed Singapore for Sydney on 5 November 2010 when its number one Rolls-Royce RB211-524G engine failed while it was climbing through 2000 ft.
The aircraft returned to Singapore after the flight crew dumped fuel.
Inspections of the engine showed that the powerplant's HPC stage one blade had "liberated at the blade root", said the Australian Transport Safety Bureau in its final report into the incident.
The liberated blade resulted in severe damage to all stages of the HPC.
The blade root failure and subsequent damage to the HPC were "consistent with previous HPC stage one root failures", said the ATSB.
Including the November 2010 incident, Qantas had experienced nine such blade root failures, it added.
Engine manufacturer Rolls-Royce had previously issued three service bulletins for the engine to address blade issues prior to the incident, said the Bureau.
The latest of the three service bulletins, issued in February 2009, had introduced a modified blade "with a revised geometry" which "could provide protection against root failures".
"The revised geometry was designed to be more tolerant to stresses induced by blade tip rub," said the ATSB.
This modified blade had not been incorporated into the engine that failed in the Qantas incident.
Currently, about 18 per cent of Qantas' RB211-524G engines have been modified to the latest standard, said the ATSB and in response to the incident, Qantas is continuing to modify its engines to the latest standard at engine shop visits.
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