Incident Overview
The aircraft experienced an uncontained disintegration of its No.2 engine during flight. Scorched engine fragments ripped through the fuselage, injuring two passengers. One of the injured passengers sustained serious injuries, while the other suffered minor injuries.
Cause of Failure
Investigation determined that the uncontained failure was the result of wear or spalling of the 1st stage reduction gear and the sun gears. Progressive contamination of the lubrication system allowed the wear to escalate, ultimately leading to the uncontained disintegration.
Contributing Factor
A contributing factor to the ultimate failure was an inoperative magnetic chip detector plug. This component would normally detect metallic debris in the oil system, alerting maintenance personnel to abnormal wear. Because the plug was not functioning, the wear progressed undetected until catastrophic failure occurred.
Damage and Injuries
The engine fragments that penetrated the fuselage caused structural damage to the aircraft cabin. Two passengers were struck by the debris; one required hospitalization for serious injuries, and the other was treated for minor injuries. The aircraft itself sustained damage from the uncontained failure and fragment impact.