It is always dangerous to speculate about causes of incidents such as the Qantas A380 engine failure today, but there has been some evidence of Rolls-Royce Trent 900 problems.
As our engine guru Guy Norris reported back in September, the European Aviation Safety Agency has issued an airworthiness directive (AD) for the Airbus A380’s Trent 900 engine intermediate pressure shaft which, if not performed, could result in an uncontained engine failure similar to those that have affected a Trent 1000 Rolls is developing for the Boeing 787. The AD says wear beyond normal limits has been identified on the abutment faces of the splines on the Trent 900 IP shaft rigid coupling on several engines during strip.
As the shaft-to-coupling spline interface provides the means of controlling the turbine axial setting, the wear through of the splines would permit the IP turbine to move rearward, it adds. This rearward movement “would enable contact with static turbine components and would result in loss of engine performance with potential for in-flight shut down, oil migration and oil fire below the [low pressure] turbine discs prior to sufficient indication resulting in loss of LP turbine disc integrity.”
Although the AD, which requires inspection of the IP shaft coupling splines, appears to bear an uncomfortable resemblance to the Trent 1000 issues, industry sources maintain the two are unconnected.