Failure Analysis of First Stage Turbine Air Seal Assembly

摘要

The first stage outer turbine ring assembly from a mid-range commercial engine failed prematurely during operational service. The nickel-base turbine ring assembly served as the air seal between the first stage turbine blades and the engine casing. It was alleged that the ring was installed incorrectly, thereby causing excessive wear. Metallurgical failure analysis and finite element modeling revealed that excessive first stage turbine blade growth—most likely from abnormal engine operation—caused the turbine ring assembly failure. No evidence was found to indicate that a material deficiency or installation mishap contributed to the failure. A range of design features was explored that could possibly reduce the possibility of blade rubs.