TERMINAL ISLAND, CA, USA
N28565
GRUMMAN AMERICAN AA-5B
DURING AN OVERWATER FLT TO CROSS A 23 MI CHANNEL, THE ENG BEGAN TO RUN ROUGH & LOOSE POWER. THE PLT TURNED TOWARD THE SHORE & MADE A FORCED LANDING ON A DIRT ROAD ON TERMINAL ISLAND. BEFORE THE ACFT STOPPED, IT COLLIDED WITH A FENCE & SVRL PARKED CARS IN A STORAGE LOT. AN EXAM OF THE ENG REVEALED THE TOP OF THE #1 PISTON & THE #1 CYLINDER HEAD WERE SEVERELY BATTERED; THE #1 EXHAUST VALVE HEAD HAD SEPD FROM ITS STEM & WAS FOUND IN THE EXHAUST SYSTEM; THE EXHAUST VALVE GUIDE WAS SEVERELY WORN AT THE EXHAUST PORT; AND THE VALVE STEM AREA WAS HEAVILY CORRODED & COKED WITH EXHAUST RESIDUE. A FATIGUE FRACTURE WAS IDENTIFIED ON A PORTION OF THE VALVE HEAD THAT WAS NOT DAMAGED. A METALLURGICAL EXAM REVEALED EVIDENCE THAT THE VALVE HAD FAILED FROM FATIGUE DUE TO OVERHEATING, WHICH RESULTED FROM A WORN OR BELL MOUTHED VALVE GUIDE.
THE FATIGUE FAILURE OF AN EXHAUST VALVE DUE TO EXCESSIVE WEAR OF THE RESPECTIVE VALVE GUIDE. FACTORS RELATED TO THE ACCIDENT WERE: THE FENCE & CARS IN THE EMERGENCY LANDING AREA.
Source: NTSB Aviation Accident Database
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