EAGLE, AK, USA
N1096X
MCDONNELL DOUGLAS 369D
SHORTLY AFTER TAKEOFF THE PILOT RADIOED HE WAS RETURNING DUE TO POOR VISUAL FLIGHT CONDITIONS, AND WAS LAST SEEN CIRCLING THE EAGLE RUNWAY. THE WRECKAGE WAS FOUND APRX 7 HRS LATER 150 YDS NORTH OF THE RUNWAY. THE BLUE M/R BLADE WAS FOUND SEPARATED; THE TRAILING ATTACHMENT LUGS OF BOTH THE UPPER AND LOWER BLADE ROOT FITTINGS WERE FRACTURED THROUGH THE HOLES, AND THE LEAD LAG DAMPENER LUG WAS ALSO FRACTURED. METALLURGICAL EXAMINATION REVEALED FATIGUE PROGRESSION ON ALL FOUR ROOT FRACTURES. OPERATOR MAINTENANCE PERSONNEL STATED THAT THEY WERE NOT AWARE OF AD91-17-04 REQUIREMENT TO REMOVE & INSPECT THE M/R BLADES AT 100-HR INTERVALS.
AN INFLIGHT FATIGUE FAILURE AND SEPARATION OF A MAIN ROTOR BLADE, INADEQUATE OPERATOR MAINTENANCE AND INSPECTION, AND MATERIAL DEFECT.
Source: NTSB Aviation Accident Database
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