AAIB investigation to Leonardo AW139, G-CIMU
Tail rotor duplex bearing failure, Norwich Airport, 13 June 2022
The failure of an AW139 tail rotor duplex bearing was identified during a post-flight maintenance check from wear damage on the bearing/actuator cover. The extent of the damage to the bearing confirmed that a loss of tail rotor control event would likely have occurred had the helicopter continued to operate with the bearing fitted. The bearing is defined as a critical part and failure of a similar design of bearing fitted to an AW169 helicopter resulted in a fatal accident in 2018. Despite a full forensic assessment, the bearing was too badly damaged to determine the cause of failure. Three Safety Recommendations have been made to address safety concerns relating to the failure of tail rotor duplex bearings on the AW139.
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