PERRIS VALLEY, CA, USA
N121PM
de Havilland DHC-6-100
AFTER LIFT-OFF, AT ABOUT 100 FT AGL AND 85 KTS, THE LEFT ENG DECELERATED AND THE AIRPLANE BEGAN TO YAW AND ROLL LEFT. THE PIC ABORTED THE TAKEOFF, TURNED LEFT AND LANDED ON A FLAT LEVEL FIELD. THE AIRPLANE STRUCK A FENCE, THEN TREES. EXAMINATION OF THE LEFT ENG REVEALED THE LOSS OF POWER WAS ATTRIBUTED TO A FATIGUE FRACTURE OF A COMPRESSOR TURBINE BLADE, WHICH LED TO SUBSEQUENT BLADE FRACTURES. THE RIGHT ENG WAS EXAMINED AND FOUND TO HAVE ADVANCE WEAR ON THE THROTTLE CAM ASSEMBLY OF THE POWER TURBINE GOVERNOR. IN A TEST CELL, ONLY APRX 28% OF TAKEOFF POWER COULD BE ACHIEVED. THE CAM LOBE WEAR HAD PROGRESSED OVER AN EXTENDED PERIOD OF TIME. THE RIGHT ENGINE PROP GOVERNOR WAS REPLACED 11/18/90, FOLLOWED BY A TEST RUN.
A LOSS OF POWER ON THE LEFT ENGINE DUE TO A FATIGUE FAILURE OF A COMPRESSOR TURBINE BLADE LEADING TO FURTHER COMPRESSOR BLADE DAMAGE; A WORN POWER TURBINE GOVERNOR THROTTLE CAM ASSEMBLY WHICH LED TO LOSS OF POWER ON THE RIGHT ENGINE; AND INADEQUATE MAINTENANCE AND INSPECTION BY THE OPERATOR.
Source: NTSB Aviation Accident Database
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