Engine Failure Investigation
Rolls-Royce, the manufacturer of the Trent 900 engine, conducted an investigation into an engine failure that resulted in a shutdown. The teardown examination revealed internally-corroded low-pressure turbine stage 2 (LPT2) blades. The corrosion was caused by chemical residue left in the hollow blades from cleaning operations during the last service in July 2015. This corrosion led to fatigue cracking, which subsequently caused the release of blade shroud debris. The debris resulted in significant downstream engine damage.
Following the findings, Rolls-Royce performed a thorough audit of its cleaning operations and implemented additional safety actions, as detailed in the safety action section of the report.
Fire Warning Analysis
The fire and overheat detection system was assessed to determine the cause of a fire warning that occurred during the event. No issues were identified in the system itself, and the fire/overheat detector assemblies were removed and returned to the vendor for further evaluation. The detector manufacturer identified wear in the unit that would have increased its sensitivity to vibration, raising the likelihood of spurious warnings. Rolls-Royce assessed that it was very likely that the wear, combined with the vibrations associated with this event, contributed to the spurious fire warning.