On February 16, 1984, a Mcdonnell Douglas DC-9-31 (registration N8924E) was involved in an aviation accident near Forest Park, GA. Investigators recorded the probable cause as: Fatigue failure of the third-stage turbine blade, induced by rubbing between the turbine shroud and the outer air seal. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
A muffled explosion and engine deterioration prompted a safe return after takeoff. Investigation revealed fatigue failure of the third-stage turbine blade due to rubbing between the shroud and outer air seal.
What happened
Shortly after takeoff, the pilot reported hearing a muffled explosion accompanied by a moderate left yaw and a noticeable deterioration in readings on the number one engine. Despite the mechanical anomaly, the aircraft was able to return to the airport for an uneventful landing.
The investigation
A post-accident examination of the affected powerplant revealed that the failure originated in the third-stage disk and blades area. A detailed metallurgical analysis confirmed that the third-stage turbine blade had suffered a fatigue failure. The examination determined that this failure was most likely induced by rubbing between the turbine shroud and the outer air seal.
Findings
The primary contributing factor to the incident was the fatigue failure of the third-stage turbine blade. This mechanical breakdown was caused by contact between the turbine shroud and the outer air seal, leading to the sudden loss of engine performance during the critical climb phase.
Probable cause
Fatigue failure of the third-stage turbine blade, induced by rubbing between the turbine shroud and the outer air seal.
