What happened
On January 9, 2013, during scheduled maintenance at Warsaw Chopin Airport (EPWA), technicians were performing work on a Boeing 73/500 engine. While dismantling the Low Pressure Turbine (LPT) Major Module from the engine, a fragment of an HPC Compressor Shaft Retaining Ring was discovered on the flame arrestor element.
Following the removal of the turbine module, further inspection revealed circumferential wear marks on both the front and rear sections of the LPT shaft. The investigation established that this damage was likely caused by the detached fragment of the retaining ring.
The investigation
The investigation focused on the damaged components and the timeline of the technical analysis. The affected parts were sent to a repair facility and the engine manufacturer for detailed examination and repair.
In May 2016, the maintenance organization contacted the engine manufacturer to request an update on the status of the technical investigation. The manufacturer responded that while they had closed the specific inquiry on their side, the technical investigation into the HPC Retaining Ring was being treated as a long-term study and would continue internally.