BEXLEY, OH, USA
N300PP
HUGHES 269C
THE HELICOPTER WAS IN CRUISE FLIGHT AT 500 FEET AGL WHEN THE ENGINE QUIT WITHOUT WARNING. AN AUTOROTATION WAS EXECUTED TO AN OPEN FIELD. THE TAILBOOM WAS SEVERED BY THE MAIN ROTOR BLADES. POST ACCIDENT EXAMINATION OF THE ENGINE REVEALED THE NO. 1 CYLINDER EXHAUST VALVE FAILED.FURTHER INVESTIGATION REVEALED THE ENGINE HAD BEEN DAMAGED PREVIOUSLY OVERSPED ABOUT 60 HOURS PRIOR THE EXHAUST VALVE FAILURE. ENGINE MAINTENANCE RECORDS CONTAINED NO EVIDENCE OF AN OVERSPEED INSPECTION BUT DID REVEAL THAT THE NO. 2 CYLINDER WAS REMOVED BECAUSE OF OIL FOULING. THE ENGINE WAS OPERATED TWO TENTHS OF AN HOUR AFTER REPLACEMENT OF THE CYLINDER AND SUFFERED FAILURE OF THE NO. 1 CYLINDER EXHAUST VALVE.
THE INADEQUATE MAINTENANCE INSPECTION OF THE ENGINE FOLLOWING EVIDENCE OF PREVIOUS DAMAGE WHICH LED TO THE FAILURE OF THE NO. 1 CYLINDER EXHAUST VALVE.
Source: NTSB Aviation Accident Database
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