What was found
AIRCRAFT OPERATOR REPORTED THE NR 1 ENGINE ON N81RC (525C-0217) MADE AN UNUSUAL NOISE DURING ENGINE SPOOL-DOWN. OPERATOR REPORTED NO ENGINE OPERATIONAL ISSUES, SYMPTOMS, OR OTHER ANOMALIES DURING THE PREVIOUS FLIGHT. DURING A SUBSEQUENT BORESCOPE INSPECTION PERFORMED BY A LOCAL SERVICE CENTER, THE TECHNICIAN REPORTED SEEING ONE LIBERATED 3RD-STAGE INTERMEDIATE PRESSURE COMPRESSOR (IPC) ROTOR BLADE. THE ENGINE WAS REMOVED AND SENT TO THE REPAIR STATION FOR DISASSEMBLY AND EVALUATION. DISASSEMBLY OF ENGINE SERIAL NUMBER 211447 CONFIRMED ONE 3RD-STAGE IPC ROTOR BLADE RELEASE AND SECONDARY DAMAGE TO IPC STATOR VANE TRAILING EDGES.