What happened
During the cruise climb phase of flight, a McDonnell Douglas DC 10 Series 10 experienced an uncontained failure of its number one engine. The failure involved the 14th through 16th stage compressor spool.
The investigation
The investigation focused on the history of the compressor spool. Approximately 11 years prior to the incident, the spool had sustained damage that exceeded maintenance manual limits. This damage was characterized by a 360-degree rub on the aft rim surface, specifically identified as surface Q, of the 16th stage compressor. Following this damage, the spool was kept in storage for five years before being repaired and returned to service.
Engine manufacturer analysis of flight profile stresses revealed that the peak stresses occurring in the aft rim region (surface Q) align with the specific timing in the flight profile when the uncontained failure took place.