What happened
On February 4, 2020, an Embra and ERJ 170-200-200 LR, registration SP-LIK, was climbing through flight level 350 after departing from Munich (EDDM). During the climb, the crew observed that the Exhaust Gas Temperature (EGT) for engine number 2 had exceeded its maximum limit. Simultaneously, a "CHIP DETECTED" warning appeared in the cockpit, indicating the presence of metal particles in the oil.
The crew immediately reduced engine power, which returned the temperature to normal levels. The flight continued to Warsaw (EPWA) at a reduced speed. Subsequent analysis of the Flight Data Recorder (FDR) revealed that the EGT had reached 963°C and remained at this elevated level for 19 seconds.
Following the flight, a borescope inspection of the combustion chamber and high-pressure turbine showed no visible damage. However, an inspection of the magnetic chip detector revealed the presence of chrome steel particles. While the engine manufacturer, GE, initially recommended only an oil system flush, further investigation of engine trend monitoring data from previous flights showed a sudden drop in EGT margin, increased fuel flow, and a decrease in oil pressure.
The investigation
On February 5, 2020, a ground engine test was conducted, which recorded high EGT, high fuel flow, and low oil pressure, leading to the termination of the test. Following inquiries to GE, a borescope inspection of the high-pressure compressor (HPC) was performed, which showed no damage.
Upon a more detailed re-examination of all findings, investigators identified evidence of wear on the abradable layer inside the turbine casing, caused by the turbine blade tips rubbing against the surface.
Findings
- The primary cause of the event was engine wear during normal operation, which led to the excessive increase in exhaust gas temperatures.
- Metal particles (chrome steel) were present in the oil system.
- Trend monitoring had previously indicated a decline in engine performance margins and oil pressure stability.