WISCONSIN DELLS, WI, USA
N3748Z
HILLER UH12L4
DURING CLIMB, AT ABOUT 200 FT AGL, THE M/R LOST RPM. DURING AUTOROTATION THE ENG RPM INCREASED BEYOND THE RED LINE WHEN THE PLT ADDED POWER. THE HELICOPTER MADE A HARD LANDING IN A RESIDENTIAL AREA. INSPECTION OF THE MERCURY CLUTCH REVEALED THAT THE EXTERIOR SURFACE OF THE CLUTCH DRUM EXHIBITED EVIDENCE OF EXCESSIVE OVERHEATING. THE INSIDE SURFACE OF THE DRUM SHOWED SEVERE GLAZING & DISCOLORATION IN THE CLUTCH SHOE WEAR AREA. THERE WERE ALSO SEVERAL CRACKS IN THE CLUTCH DRUM. THE HOUSING BEARING JOURNAL HAD EXPERIENCED SEVERE PITTING. THERE WAS ALSO SEVERE WEAR IN THE BEARING JOURNAL AREA. THE CLUTCH SHOES SHOWED SIGNIFICANT GLAZING & SURFACE CRACKING, & WERE SEVERELY WORN.
Source: NTSB Aviation Accident Database
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