FORT LAUDERDALE, FL, USA
N519DA
BOEING 727-232
AFTER GEAR RETRACTION DRG TAKEOFF, AT APRX 150' AGL, THE AIRCREW HEARD A LOUD NOISE & NOTED THE #2 ENG HAD FAILED. THEY SECURED THE ENG, DUMPED FUEL & LANDED WITHOUT FURTHER INCIDENT. AN EXAM OF THE #2 ENG REVEALED THE COMBUSTION CHAMBER OUTER CASE, PN 616315, HAD FAILED FROM HI STRESS, LOW-CYCLE FATIGUE. THE FAILURE ORIGINATED AT A 4.6 INCH CRACK AT THE REAR DRAIN BOSS TO CASE WELD. AT THE LAST SHOP INSPN, A SUSPECTED CRACK WAS VISUALLY OBSVD IN THIS AREA. THE CASE WAS PREPARED FOR NON-DESTRUCTIVE TESTING BY GRIT BLASTING IT WITH ALUMINUM OXIDE BEADS TO STRIP OFF NICKEL-CADMIUM PLATING. HOWEVER, THE TESTING DID NOT REVEAL A CRACK. THEREFORE, THE CASE WAS RECOATED WITH NICKEL-CADMIUM & RETURNED TO SVC. AFTER THE FAILURE, AN EXAM OF THE FRACTURE AREA REVEALED THE PRESENCE OF NICKEL & CADMIUM (0.5 TO 0.75 INCH, CENTERED ON THE FRACTURE ORIGIN AREA). THERE WAS EVIDENCE THAT GRIT BLASTING (PRIOR TO NON-DESTRUCTIVE TESTING) HAD MECHANICALLY CLOSED THE PREV CRACK, THUS PREVENTING DETECTION. THE OPERATOR REVISED THE SHOP PROCEDURE TO A SHELL BLASTING METHOD.
Source: NTSB Aviation Accident Database
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