MAPLETON, OR, USA
N4027K
HILLER UH-12E
WHILE APPROACHING THE SPRAY AREA, THE ACFT WAS IN A LEVEL ATTITUDE AT 20 TO 25 MPH & ABOUT 100 FT AGL WHEN THE PLT HEARD A LOUD BANG & NOTED A LOSS OF POWER. HE ATTEMPTED AN AUTOROTATIVE LANDING. DURING TOUCHDOWN ON HILLY TERRAIN, THE ACFT ROLLED TO THE RIGHT & CAME TO REST INVERTED ON A STEEP SLOPE. A TEARDOWN OF THE ENG REVEALED THAT A SPUR ADAPTER GEARSHAFT, PN 6890482, & A COMPRESSOR COUPLING ADAPTER, PN 6871472, HAD FAILED. FAILURE OF THE SPUR ADAPTER GEARSHAFT WAS DUE TO FATIGUE WHICH ORIGINATED AT AN AREA OF HEAVY WEAR ON THE LOAD SIDE OF THE FORWARD SPLINES.
Source: NTSB Aviation Accident Database
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