On 6/7/93, a catastrophic failure of the 6th stage disc assembly on the intermediate compressor 6/7th rotor shaft in the Number Three engine resulted in a significant incident. The disc ruptured, causing fuel inlet line contamination and penetrating the Number One engine and fuselage. Fire warning systems were activated, and engine fire bottles were discharged. Residual fire was extinguished by airport fire fighters. Approximately 80% of the failed disc was found, exhibiting corrosion pitting and small fatigue cracking at the attachment holes. The largest crack was 0.13′ deep and 0.23′ wide. Metallurgical examination revealed corrosion pitting and fatigue cracking, indicating a failure of the attachment holes. A critical component, the telltale marker for the flight engineer’s Number Three engine gauge, showed a 106% reading compared to the calibrated 118% reading, indicating an overspeed condition. The rotor exceeded EPR limits and had been previously verified as safe for operation. Service Bulletin (SB) RB.211-72-9569 mandated the removal of rotor components exceeding 14,000 cycles by 4/30/93. The rotor had 16,327 cycles at the time, triggering a mandatory requirement in the UK but not in the US. The incident was likely caused by the failure of the sixth stage disc assembly due to corrosion pitting and fatigue cracking of the failed disc. A contributing factor was the airline company’s failure to fully comply with the Service Bulletin (SB) RB.211-72-9569, and foreign object damage to the Number One engine, resulting from the failure of the Number Three engine.On 6/7/93, a catastrophic failure of the 6th stage disc assembly on the intermediate compressor 6/7th rotor shaft in the Number Three engine resulted in a significant incident. The disc ruptured, causing fuel inlet line contamination and penetrating the Number One engine and fuselage. Fire warning systems were activated, and engine fire bottles were discharged. Residual fire was extinguished by airport fire fighters. Approximately 80% of the failed disc was found, exhibiting corrosion pitting and small fatigue cracking at the attachment holes. The largest crack was 0.13′ deep and 0.23′ wide. Metallurgical examination revealed corrosion pitting and fatigue cracking, indicating a failure of the attachment holes. A critical component, the telltale marker for the flight engineer’s Number Three engine gauge, showed a 106% reading compared to the calibrated 118% reading, indicating an overspeed condition. The rotor exceeded EPR limits and had been previously verified as safe for operation. Service Bulletin (SB) RB.211-72-9569 mandated the removal of rotor components exceeding 14,000 cycles by 4/30/93. The rotor had 16,327 cycles at the time, triggering a mandatory requirement in the UK but not in the US. The incident was likely caused by the failure of the sixth stage disc assembly due to corrosion pitting and fatigue cracking of the failed disc. A contributing factor was the airline company’s failure to fully comply with the Service Bulletin (SB) RB.211-72-9569, and foreign object damage to the Number One engine, resulting from the failure of the Number Three engine.