What was found
ENGINE DISASSEMBLY TO INVESTIGATE AND REPAIR TURBINE SECTION FAILURE REVEALED CAUSE TO BE FIRST STAGE ROTOR BLADE FAILURE. BLADE SEPARATED AT FIR TREE AIR PASSAGE. TURBINE SECTION COMPONENTS IN DOWNSTREAM GAS PATH EXPERIENCED SEVERE UNREPAIRABLE DAMAGE DUE TO BLADE FAILURE/IMPACT. NO SIGNS OF ABNORMAL OPERATION PRIOR TO BLADE FAILURE. METALLURGICAL CASTING DEFECT (MICRO-SHRINGKAGE) AS POSSIBLE CAUSE. CYCLES, 2,639.