What happened
On November 25, 2014, during a scheduled borescope inspection (BSI) as part of a maintenance check at Warsaw Chopin Airport (EPWA), maintenance personnel discovered internal damage within the high-pressure compressor (HPC) of an Embraer 175 engine. The aircraft, registration SP-LIE, was operated by PLL LOT S.A. The inspection revealed damage to the compressor blades, shroud, and vane attachment points. Specifically, two blades exhibited damage exceeding established maintenance limits. Following the discovery, the affected engine (ESN 193442) was replaced with a different unit (ESN 193146).
The investigation
The investigation focused on identifying the source of the compressor damage and determining if this was an isolated event. The investigation established that this incident was the fourth recorded instance of engine damage caused by rotor-stator contact within the operator's fleet. The investigation also reviewed the engine manufacturer's (GE) involvement and the effectiveness of existing maintenance and software protocols for monitoring engine health.
Findings
- The primary cause of the damage was rotor-stator contact within the high-pressure compressor.
- This contact was triggered by material fatigue affecting a stator element.
- The incident was part of a recurring pattern of similar engine damage involving the same mechanical phenomenon across the fleet.