SALINAS, CA, USA
N169HA
HILLER UH21E
THE PLT EXPERIENCED A 'RATCHETING' TO THE RIGHT AND A DECREASE IN ROTOR RPM DURING CRUISE FLT AT 75-100 FT AGL. THE PLT MADE AN AUTOROTATION BUT COULD NOT CUSHION THE LANDING DUE TO THE LOW ALT AND LACK OF ROTOR RPM. THE HELICOPTER IMPACTED HARD AND CARTWHEELED. POST ACCIDENT EXAMINATION OF THE HELICOPTER REVEALED THE UPPER HOUSING OIL ORIFICE WAS COMPLETELY BLOCKED WITH A FOREIGN MATERIAL WHICH RESULTED IN OIL STARVATION TO THE SECONDARY PLANET SYSTEM. THE FOREIGN MATERIAL WAS ANALYZED AND FOUND TO CONTAIN 'SIGNIFICANT QUANTITIES OF SILICON'.
Source: NTSB Aviation Accident Database
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