Failure Analysis of a Welded AISI321 Steel Bleed Air Connector of an Aircraft Engine

Failure investigation was conducted on a bleed air connector of an aircraft engine that developed opening during service. The fabricated tubular structure wherein the flanges were circumferentially welded to bent pipe both ends. and made austenitic stainless steel AISI 321. Fractography study confirmed had failed by fatigue mechanism. Fatigue crack initiated at one weld joints. exact location initiation weld-to-tube interface. After initiation, propagated into resulting in loss material fracture. Investigation revealed primary cause stress concentration joint from improper design. Inferior quality another factor contributed failure. A detailed analysis failure is presented this article remedial measures suggested for preventing recurrence similar failures.