STARKE, FL, USA
N9373B
CESSNA 175
FLT WAS 3 MILES EAST OF ARPT RETURNING TO LAND AT ALT OF APRX 2,000 FT, WHEN THE ENG QUIT. PLT WAS UNABLE TO RESTART & ELECTED TO LAND IN SMALL TREES AS A NEARBY HIGHWAY WAS CONGESTED. ACFT COLLIDED WITH TREES & FELL TO THE GROUND. EXAMINATION OF THE ENG REVEALED THE CRANKSHAFT FAILED AT THE REAR CRANKSHAFT CHEEK BETWEEN #1 & #2 CYLINDER CONNECTING RODS. METALLURGICAL EXAMINATION OF THE FAILED CRANKSHAFT REVEALED LOW & HIGH CYCLE FATIGUE. EVIDENCE INDICATED THAT THIS WAS CAUSED BY VIBRATIONS OF THE CRANKSHAFT DURING CONTACT OF THE THREE DYNAMIC COUNTERWEIGHTS TO THE ADJACENT CAMSHAFT LOBES. COUNTERWEIGHT CONTACT WAS CAUSED BY WORN COUNTERWEIGHT BUSHING. REVIEW OF THE ENG LOGBOOKS REVEALED A MAJOR OVERHAUL WAS PERFORMED IN 1969, APRX 793 HRS PRIOR TO THE FAILURE. THREE TOP OVERHAULS WERE PERFORMED. THE FIRST & SECOND PERFORMED AT ONE YEAR INTERVALS AFTER THE MAJOR. THE THIRD WAS PERFORMED 10 YEARS AFTER THE SECOND.
Source: NTSB Aviation Accident Database
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