LAKE ISABELLA, CA, USA
N704GL
CESSNA 150M
AFTER TAKEOFF, THE ACFT WAS FLOWN APRX 5 MI SOUTH OF THE ARPT & WAS AT ABOUT 1000 FT ABOVE A LAKE WHEN THE ENG BEGAN VIBRATING VIOLENTLY & LOSING POWER. THE PLT TURNED TOWARD THE SHORE & TRIED VARIOUS MIXTURE SETTINGS IN AN ATTEMPT TO CORRECT THE PROBLEM. SUBSEQUENTLY, DURING A FORCED LANDING, THE ACFT COLLIDED WITH A FENCE. AN EXAM OF THE ENG REVEALED THAT THE STARTER GEAR WAS DETACHED FROM THE STARTER SHAFT. METAL FRAGMENTS WERE FOUND IN NUMEROUS AREAS OF THE ENG, INCLUDING THE OIL SCREEN, WHICH HAD COLLAPSED. THE OIL PUMP GEAR CAVITIES WERE SCORED, AS WELL AS THE CRANKSHAFT MAIN JOURNAL BEARINGS, WHICH EXHIBITED EXTENSIVE COPPER LAYER EXPOSURE. THE FRONT JOURNAL BEARINGS WERE ALSO EMBEDDED WITH ALUMINUM. THE #1 CONNECTING ROD HAD SEPARATED FROM ITS CRANKPIN. THE CRANKPIN WAS DISCOLORED & HAD FRAGMENTS OF STEEL WELDED TO THE JOURNAL. BOTH CONNECTING ROD CAP BOLTS OF THE FAILED ROD WERE NECKED DOWN AT THE FRACTURE FACES.
Source: NTSB Aviation Accident Database
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