What happened
The aircraft was operating as part of a scheduled transcontinental service traveling from New York to Los Angeles. During the cruise phase of the flight, several stage one high-pressure turbine rotor blades within the number one engine separated without warning from their platforms.
The investigation
Examination of the failed components revealed that the initial separation originated at a forward cooling hole on one of the blades. Forensic analysis determined that the failure was fatigue-induced. Further investigation into the root cause identified that the fatigue was likely triggered by a degradation of the cooling airflow pattern within the blade. This disruption in airflow was caused by an air leak that was not associated with the standard blade cooling holes.
Findings
The separation of these rotor blades resulted in the complete disintegration of the high-pressure turbine assembly. This mechanical failure led directly to the subsequent loss of power and engine failure on the affected engine.